Pimavanserin

• MF C₂₅H₃₄FN₃O₂
• MW 427.555

Pimavanserin, ACP 103, ACP-103; BVF-048

N-(4-fluorophenylmethyl)-N-(1-methylpiperidin-4-yl)-N’-(4-(2-methylpropyloxy)phenylmethyl)carbamide,

706779-91-1 (Pimavanserin )
706782-28-7 (Pimavanserin Tartrate)

for treatment of psychotic symptoms in patients with Parkinson’s disease

WATCH OUT AS THIS POST IS UPDATED………..

Trade Name：Nuplazid^®

MOA：5-HT2A inverse agonist

Indication：Hallucinations and delusions associated with Parkinson’s disease psychosis

Company：Acadia (Originator)

APPROVED US FDA 2016-04-29, ACADIA PHARMS INC, (NDA) 207318

To treat hallucinations and delusions associated with psychosis experienced by some people with Parkinson’s disease

	706782-28-7 (tartrate)

Urea, N-[(4-fluorophenyl)methyl]-N-(1-methyl-4-piperidinyl)-N’-[[4-(2-methylpropoxy)phenyl]methyl]-, (2R,3R)-2,3-dihydroxybutanedioate (2:1)

Pimavanserin Tartrate was approved by the U.S. Food and Drug Administration (FDA) on Apr 29, 2016. It was developed by Acadia, then marketed as Nuplazid^® by Acadia in US.

Pimavanserin Tartrate is a 5-HT_2A receptor inverse agonists, used to treat hallucinations and delusions associated with psychosis experienced by some people with Parkinson’s disease.

Nuplazid^® is available as tablet for oral use, containing 17 mg of pimavanserin. Recommended dose is 34 mg, taken orally as two tablets once daily.

Pimavanserin (INN), or pimavanserin tartate (USAN), marketed under the trade name Nuplazid, is a non-dopaminergic atypical antipsychotic^[2] developed by Acadia Pharmaceuticals for the treatment of Parkinson’s disease psychosis and schizophrenia. Pimavanserin has a unique mechanism of action relative to other antipsychotics, behaving as a selective inverse agonist of theserotonin 5-HT_2A receptor, with 40-fold selectivity for this site over the 5-HT_2C receptor and no significant affinity or activity at the5-HT_2B receptor or dopamine receptors.^[1] The drug has met expectations for a Phase III clinical trial for the treatment ofParkinson’s disease psychosis,^[3] and has completed Phase II trials for adjunctive treatment of schizophrenia alongside anantipsychotic medication.^[4]

Pimavanserin is expected to improve the effectiveness and side effect profile of antipsychotics.^[5][6][7] The results of a clinical trial examining the efficacy, tolerability and safety of adjunctive pimavanserin to risperidone and haloperidol were published in November 2012, and the results showed that pimavanserin potentiated the antipsychotic effects of subtherapeutic doses ofrisperidone and improved the tolerability of haloperidol treatment by reducing the incidence of extrapyramidal symptoms.^[8]

On September 2, 2014, the United States Food and Drug Administration granted Breakthrough Therapy status to Acadia’s New Drug Application for pimavanserin.^[9] It was approved by the FDA to treat hallucinations and delusions associated with psychosis experienced by some people with Parkinson’s disease on April 29, 2016.^[10]

Clinical pharmacology

Pimavanserin acts as an inverse agonist and antagonist at serotonin 5-HT_2A receptors with high binding affinity (K_i 0.087 nM) and at serotonin 5-HT_2C receptors with lower binding affinity (K_i 0.44 nM). Pimavanserin shows low binding to σ₁ receptors (K_i 120 nM) and has no appreciable affinity (K_i >300 nM) to serotonin 5-HT_2B, dopaminergic (including D₂), muscarinic, histaminergic, oradrenergic receptors, or to calcium channels.^[2]

Pimavanserin tartrate, 1-(4-fluorobenzyl)-3-(4-isobutoxybenzyl)-1-(1-methylpiperidin-4-yl)urea L-hemi-tartrate, has the following chemical structure:

Pimavanserin tartrate was developed by Acadia Pharmaceuticals and was approved under the trade name NUPLAZID® for use in patients with Parkinson’s disease psychosis.

Pimavanserin free base and its synthesis are disclosed in US 7,601,740 (referred to herein as US ‘740 or the ‘740 patent) and US 7,790,899 (referred to herein as US ‘899 or the ‘899 patent). US ‘740 discloses the synthesis of Pimavanserin free base (also referred to herein as“Compound A”), which includes O-alkylation followed by ester hydrolysis, and then in situ azidation. This process suffers from low process safety, and utilizes the hazardous reagent diphenylphosphoryl azide. The process is illustrated by the following Scheme 1.

Scheme 1:

US ‘899 describes another process, which includes O-alkylation followed by aldehyde reductive amination to obtain an intermediate which is then reacted with the hazardous reagent phosgene. This process is illustrated by the following Scheme 2:

Scheme 2:

Both of the above processes for the preparation of Pimavanserin include a reaction between 1-isobutoxy-4-(isocyanatomethyl)benzene, a benzyl isocyanate intermediate, and N-(4-fluorobenzyl)-1-methylpiperidin-4-amine. Processes for preparing benzyl isocyanate derivatives are generally described in the literature, such as in US ‘740; US ‘899; Bioorganic & Medicinal Chemistry, 21(11), 2960-2967, 2013; JP 2013087107; Synthesis (12), 1955-1958, 2005; and Turkish Journal of Chemistry, 31(1), 35-43, 2007. These processes often use the hazardous reagents like phosgene derivatives or diphenylphosphoryl azide.

Synthetic route:

First, reduction of the ketone and a secondary amine to amine condensation after S-3 . 4- hydroxybenzaldehyde etherification, followed by condensation with hydroxylamine to give the oxime S-. 7 , which is then reduced by hydrogenation to the amine S-. 8 , S.8- light gas reaction to give the isocyanate S-. 9 , S. 9- react with the primary amine can be obtained Nuplazid ( pimavanserin ).Kg product can be obtained by this route.

WO2006036874

https://www.google.com/patents/WO2006036874A1?cl=en

Example 1 : Preparation of N-(4-fluorobenzyl)-N-( 1 -methylpiperidin-4-yl)-N’ -( 4-(2- methylpropyloxy)phenylmethyl)carbamide a) Preparation of

Tπacetoxy borohydπde (6.5 kg) was added over 1.5 h to a solution of N- methylpiperid-4-one (3.17 kg) and 4-fluorobenzylamme (3.50 kg) in methanol (30 1), maintaining the temperature under 27 ⁰C. The reaction mixture was stirred for 15 h at 22 ⁰C. The residual amine was checked by gel chromatography (4-fluorobenzylamine: < 5%). A solution of 30% sodium hydroxide (12.1 kg) in water (13.6 kg) was added in 75 minutes (min) maintaining the temperature under 20 ⁰C. Methanol was distilled off to a residual volume of 26 litters. Ethyl acetate was added (26 L), the solution was stirred for 15 min, the phases were decanted over 15 min and the lower aqueous phase was discarded. Ethyl acetate was distilled under reduced pressure from the organic phase at 73-127 ⁰C. At this stage the residue was mixed with a second crude batch prepared according to this method. The combined products were then distilled at 139-140 ⁰C / 20 mbar to yield 11.2 kg product (> 82%). b) Preparation of

4-Hydroxybenzaldehyde (4.0 kg) and ethanol (20 1) were added to a solution of isobutyl bromide (9.0 kg) in ethanol (15 1). Potassium carbonate (13.6 kg) was added and the suspension was refluxed (74-78 ⁰C) for 5 days. The residual 4- hydroxybenzaldehyde was checked by HPLC (< 10%). The suspension was cooled to 20 ⁰C and used in the next step.

c) Preparation of

] Hydroxylamine (50% in water, 8.7 kg) was added to the product from previous step b)(174 1, 176 kg) and ethanol (54 1). The suspension was refluxed (77 ⁰C) for 3 h. Unreacted residual amounts of the compound of step b was checked by HPLC (< 5%). The suspension was cooled to 30 ⁰C, filtered and the filter was washed with ethanol (54 1). The solution was concentrated by distillation under reduced pressure at 30 ⁰C to a residual volume of 67 litters. The solution was cooled to 25 ⁰C and water (110 1) was added. The suspension was concentrated by distillation under reduced pressure at 30 ⁰C to a residual volume of 102 litters. Petrol ether (60-90 fraction, 96 1) was added and the mixture was heated to reflux (70 ⁰C). The solution Λvas cooled to 40 ⁰C and crystallization was initiated by seeding. The suspension was cooled to 5 ⁰C and stirred for 4h. The product was centrifuged and the cake was washed with petrol ether (60-90 fraction, 32 1). The wet cake was dried at about 40 ⁰C to yield 16kg product (63%).

d) Preparation of

[0105] The product from previous step c) (15.7 kg) was dissolved in ethanol (123 1). Acetic acid (8.2 kg) and palladium on charcoal 5% wet (1.1 kg) were added. The oxime was hydxogenated at 22 ⁰C and 1.5 bar for 4h. Consumption of oxime was checked by HPLC (for information). The catalyst was filtered and the solvent was distilled under reduced pressure at 36 ⁰C to a final volume of 31 1. Ethyl acetate (63 1) was added and the mixture was heated to reflux (75 ⁰C) until dissolution. The solution was cooled to 45 ⁰C and the crystallization was initiated by seeding. The suspension was cooled to 6-10 ⁰C and stirred for 2.5h. The product was centrifuged and the cake was washed with 2 portions of ethyl acetate (2 x 0.8 1). The wet cake was dried at a temperature of about 40 ⁰C to yield 8 kg (41%).

e) Preparation of

Aqueous sodium hydroxide (30%, 5.0 kg) was added to a suspension of the product from previous step d) (7.9 kg) in heptane (41 1). The solution was heated to 47 ⁰C, stirred for 15 mm and decanted o~ver 15 mm. The pH was checked (pH>12) and the aqueous phase was separated. The solvent was removed by distillation under reduced pressure at 47-65⁰C. Heptane was added (15 1) and it was removed by distillation under reduced pressure at 58-65 ⁰C. Heptane was added (7 1), the solution was filtered and the filter was washed with heptane (7 1). The solvent was removed by distillation under reduced pressure at 28-60 ⁰C. Tetrahydrofuran (THF, 107 1) and tπethylamme (TEA, 6.8 kg) were added and the temperature was fixed at 22 ⁰C. In another reactor, phosgene (5.0 kg) was introduced in tetrahydrofuran (88 1) previously cooled to -3 ⁰C. The THF and TEA s olution was added to the solution of phosgene in 3h 50 mm maintaining the temperature at -3 ⁰C. The reactor was washed with tetrahydrofuran (22 1). The mixture was stirred for 45 min at 20 ⁰C and then for 90 min at reflux (65 ⁰C). The solvent was distilled under reduced pressure at 25-30 ⁰C to a residual volume of 149 1. The absence of phosgene was controlled. At this stage, there still was phosgene and the suspension was degassed by bubbling nitrogen through it. After this operation the level of phosgene above the solution was below 0.075 ppm. The suspension was filtered and washed with tetrahydrofuran (30 1). The solvent was distilled under reduced pressure at 20-25 ⁰C to a residual volume of 40 1. Tetrahydrofuran (51 1) was added and the solvent was distilled under reduced pressure at 20-25 ⁰C to a residual volume of 40 1. The final volume was adjusted to about 52 litters by addition of tetrahydrofuran (11 1). The solution was analysed and used in the next step. f) Preparation of the title compound of formula I

The product from previous step e) (51 1) was added in 1 h to a solution of the product from step a) (7.3 kg) in tetrahydrofuian (132 1) at 17 ⁰C. The line was washed with tetrahydrofuran (12 1) and the mixture was stirred for 15h. Residual product from the first step was checked by HPLC The solvent was removed ^“by distillation under reduced pressure at 20-38 ⁰C to a residual volume of 165 1. Charcoal (Noπt SXl-G, 0 7 kg) was added, the mixture was stirred for 15 mm and filtered. The lme was washed with tetrahydrofuran (7 1) and the solvent was removed by distillation under reduced pressure at 20-25 ⁰C to a residual volume of 30 1. Isopropyl acetate (96 1) was added to obtain a solution of the title compound of formula I, which contains a small amount of impurities, which were mainly side products from the previous reactions. Removal of the solvent from a sample yields a substantially amorphous solid

g) Preparation of N-(4-fluorobenzyl)-N-(l-methylpipeπdm-4-yl)-N’-(4-(2-methylpropyloxy)phe- nylmethyl)carbamide hemi-tartrate

To the solution of the compound of Formula I in isopropyl acetate (96 1) from step f was added at 23 ⁰C a previously prepared solution of tartaric acid (1 7 kg) in water (1.7 1) and tetrahydrofuran (23 1) The residual suspension was stirred for 2.5 days at 22 ⁰C The tartrate crude product was centrifuged and the cake was washed with 4 portions of isopropyl acetate (4 x 23 1). A total of 107 kg of mother liquors was saved for later use in obtaining the tartrate salt The wet cake was dπed at about 40 ⁰C to yield 8.3 kg (50%) product.

h) First Purification

The tartrate crude product of step g) (8.1 kg) was dissolved m demmeralized water (41 1) at 22 ⁰C. Isopropyl acetate (40 L), 30% aqueous sodium hydroxide (4.3 kg) and sodium chloride (2 kg) were added. The pH was checked (>12) and the solution was stirred for 15 mm. The solution was decanted over 15 mm and the aqueous phase was separated. The aqueous phase was re-extracted with isopropyl acetate (12 1) Demmeralized water (20 1) and sodium chloride (2 0 kg) were added to the combined organic phases, the solution was stirred for 15 mm, decanted over 15 mm and the aqueous phase was discarded. Charcoal (0.4 kg) was added, the mixture was stirred for 20 mm and filtered. After a line wash with isopropyl acetate (12 1), the solvent was removed under reduced pressure at 20-25 ⁰C Heptane (49 1) was added and the suspension was stirred for 15 mm at 40 °C. Then, 8 1 of solvent was removed by distillation under reduced pressure at 38-41 ⁰C The slurry was cooled to 20 ⁰C and stirred for 1 h. The product was centrifuged and the cake was washed with heptane (5 1) The wet compound of Forrnu-la I (5.5 kg) was dissolved m ethanol (28 1) at 45 ⁰C. A solution of tartaric acid (0.72 kg) m ethanol (11 1) was added at 45 ⁰C and the line was washed with ethanol (91). The solution was cooled to 43 ⁰C, seeded with the tartrate salt of the compound o f Formula I, then the slurry was cooled to 35⁰C m 30 mm, stirred at this temperature for 1 h and cooled to -5 ⁰C After 14 h at this temperature the product was centrifuged and washed with two portions of ethanol (2×6 1) The wet cake was dried at about 45 ⁰C for 76 h to yield 4 kg of the herm-tartrate

i) Re -crystallization

150 O g of herm-tartrate obtained m h) was dissolved under stirring at 65 ⁰C m 112 ml absolute ethanol and then cooled under stirring to 48 ⁰C at a cooling rate of 1 °C/mm Crystallization started after a few minutes at this temperature and the suspension turned to a thick paste withm 1 h. The suspension was heated again to 60 ⁰C and then cooled to 48⁰C at a rate of 1 °C/mm The obtained suspension was stirred and was cooled to 15 ⁰C at a cooling rate of 3 °C/h. The crystalline precipitate was separated by filtration and the bottle was washed with 10 ml absolute ethanol cooled to 5 ⁰C. The crystalline residue was dried under vacuum and 40 ⁰C for 50 hours to yield 146 g crystalline pure herm-tartrate.

j) Second purification

15 78 g of the tartrate salt prepared from step i) was dissolved 121 130 ml water 500 ml TBME was added and the pH -was adjusted to 9 8 by addition of 2 ISf NaOH solution. After precipitation of a white solid, the aqueous phase was extracted 5 times by 500 ml TBME The organic phases were concentrated until a volume of about 400 ml remained. The solution was stored at 6⁰C. The precipitate was filtered, washed with TBME and finally dried m vacuum for 5 hours. Yield: 8.24 g of a white poΛvder. The mother liquor was concentrated to a fourth and stored at 6⁰C. The precipitate was filtered and dried m vacuum for 18 hours. Yield: 1.6 g of a white powder.

PXRD revealed a crystalline compound of formula I. No Raman peaks from tartaric acid were found. The first scan of DSC (-50⁰C to 210⁰C₅ 10°K/mm) revealed a melting point at 123.6°C. Above about 19O⁰C, the sample started to decompose. Example 2. Preparation of N-(4-fluoroben2yl)-N-(l-methylpiperidin-4-yl)-N’-(4-(2- methylpropγloxy)phenylmethyl)carbamide citrate of formula FV

a) 90 mg of the product from Example 1 and 40 mg citnc acid were suspended m 5.0 ml ethylacetate. The suspension was stirred at 60 ⁰C for 15 minutes (mm), cooled to 23±2 ⁰C, and then stored for 30 mm at 23±2 ⁰C. The precipitate was filtered off and dried in air for 30 mm to yield 52 mg of a crystalline white powder. Optical microscopy shows that the obtained solid was crystalline

b) 182 mg of the product from Example 2 and 78.4 mg citric acid were suspended m 10.0 ml ethyl acetate The suspension was stirred at 60 ⁰C for 30 mm, then stirred at 40 ⁰C for 90 mm, and finally stirred for 60 mm at 23 ⁰C The suspension was filtered and washed with heptane, yielding 237 mg of a white crystalline powder -with an endothermic peak near 153 ⁰C (enthalpy of fusion of about 87 J/g), determined by differential scanning caloπmetry at a rate of 10K/mm (DSC). Thermogravimetry (TG-FTIR) showed a mass loss of about 0.7% between 60 and 160 ⁰C, which was attributed to absorbed water Decomposition started at about 170 ⁰C Solubility m water was about 14 mg/ml The crystalline powder remained substantially unchanged when stored for 1 week at 60 ⁰C and about 75% r_h. m an open container (HPLC area was 99.4% compared to reference value of 99.9%). Elemental analysis and ¹H-NMR complies with an 1 : 1 stoichiometry.

PATENT

http://www.google.im/patents/WO2008144326A2?cl=en

Example 1 : Preparation of N-(4-fluorobenzyl)-N-Cl-methylpiperidin-4-yl)-N’-(^‘4-f2- methylpropyloxy)phenylmethγl)carbamide a) Preparation of

Triacetoxy borohydride (6.5 kg) was added over 1.5 h to a solution of N- methylpiperid-4-one (3.17 kg) and 4-fluorobenzylamine (3.50 kg) in methanol (30 L) maintaining the temperature under 27 ⁰C. The reaction mixture was stirred for 15 h at 22 ⁰C. The residual amine was checked by gel chromatography (4-fluorobenzylamine: < 5%). A solution of 30% sodium hydroxide (12.1 kg) in water (13.6 kg) was added in 75 minutes (min) maintaining the temperature under 20 ⁰C. Methanol was distilled off to a residual volume of 26 litres. Ethyl acetate was added (26 L), the solution was stirred for 15 min, the phases were decanted over 15 min and the lower aqueous phase was discarded. Ethyl acetate was distilled under reduced pressure from the organic phase at 73-127 ⁰C. At this stage the residue was mixed with a second crude batch prepared according to this method. The combined products were then distilled at 139-140 ⁰C / 20 mbar to yield 11.2 kg product (> 82%). b) Preparation of

4-Hydroxybenzaldehyde (4.0 kg) and ethanol (20 L) were added to a solution of isobutyl bromide (9.0 kg) in ethanol (15 L). Potassium carbonate (13.6 kg) was added and the suspension was refluxed (74-78 ⁰C) for 5 days. The residual 4- hydroxybenzaldehyde was checked by HPLC (< 10%). The suspension was cooled to 20 °C and used in the next step.

c) Preparation of

[0117] Hydroxylamine (50% in water, 8.7 kg) was added to the product from previous step b) (174 L₅ 176 kg) and ethanol (54 L). The suspension was refluxed (77 ⁰C) for 3 h. Unreacted residual was checked by HPLC (< 5%). The suspension was cooled to 30 °C, filtered and the filter was washed with ethanol (54 L). The solution was concentrated by distillation under reduced pressure at 30 ⁰C to a residual volume of 67 litters. The solution was cooled to 25 ⁰C and water (1 10 L) was added. The suspension was concentrated by distillation under reduced pressure at 30 °C to a residual volume of 102 litters. Petrol ether (60-90 fraction, 96 L) was added and the mixture was heated to reflux (70 °C). The solution was cooled to 40 ⁰C and crystallization was initiated by seeding. The suspension was cooled to 5 ⁰C and stirred for 4h. The product was centrifuged and the cake was washed with petrol ether (60-90 fraction, 32 L). The wet cake was dried at about 40 °C to yield 16kg product (63%). d) Preparation of

The product from previous step c) (15.7 kg) was dissolved in ethanol (123 L). Acetic acid (8.2 kg) and palladium on charcoal 5% wet (1.1 kg) were added. The oxime was hydrogenated at 22 ⁰C and 1.5 bar for 4h. Consumption of oxime was checked by HPLC. The catalyst was filtered and the solvent was distilled under reduced pressure at 36 °C to a final volume of 31 L. Ethyl acetate (63 L) was added and the mixture was heated to reflux (75 ⁰C) until dissolution. The solution was cooled to 45 ⁰C and the crystallization was initiated by seeding. The suspension was cooled to 6-10 °C and stirred for 2.5h. The product was centrifuged and the cake was washed with 2 portions of ethyl acetate (2 x 0.8 L). The wet cake was dried at a temperature of about 40 ⁰C to yield 8 kg (41%).

e) Preparation of

Aqueous sodium hydroxide (30%, 5.0 kg) was added to a suspension of the product from previous step d) (7.9 kg) in heptane (41 L). The solution was heated to 47 °C, stirred for 15 min and decanted over 15 min. The pH was checked (pH>12) and the aqueous phase was separated. The solvent was removed by distillation under reduced pressure at 47-65 °C. Heptane was added (15 L) and then removed by distillation under reduced pressure at 58-65 ⁰C. Heptane was added (7 L), the solution was filtered, and the filter was washed with heptane (7 L). The solvent was removed by distillation under reduced pressure at 28-60 ⁰C. Tetrahydrofuran (THF, 107 L) and triethylamine (TEA, 6.8 kg) were added and the temperature was fixed at 22 ⁰C. In another reactor, phosgene (5.0 kg) was introduced in tetrahydrofuran (88 L) previously cooled to -3⁰C. The THF and TEA solution was added to the solution of phosgene in 3h 50 min, maintaining the temperature at – 3 ⁰C. The reactor was washed with tetrahydrofuran (22 L). The mixture was stirred for 45 min at 20 ⁰C and then for 90 min at reflux (65 ⁰C). The solvent was distilled under reduced pressure at 25-30 ⁰C to a residual volume of 149 L. The absence of phosgene was controlled. At this stage, phosgene was still present and the suspension was degassed by bubbling nitrogen through it. After this operation, the level of phosgene above the solution was below 0,075 ppm. The suspension was filtered and washed with tetrahydrofuran (30 L). The solvent was distilled under reduced pressure at 20-25 ⁰C to a residual volume of 40 L. Tetrahydrofuran (51 L) was added and the solvent was distilled under reduced pressure at 20- 25 ⁰C to a residual volume of 40 L. The final volume was adjusted to about 52 litters by addition of tetrahydrofuran (1 1 L). The solution was analysed and used in the next step.

f) Preparation of the title compound of formula I

The product from previous step e) (51 L) was added in 1 h to a solution of the product from step a) (7.3 kg) in tetrahydrofuran (132 L) at 17 ⁰C. The line was washed with tetrahydrofuran (12 L) and the mixture was stirred for 15h. Residual product from the first step was checked by HPLC. The solvent was removed by distillation under reduced pressure at 20-38 ⁰C to a residual volume of 165 L. Charcoal (Norit SXl-G₅ 0.7 kg) was added, the mixture was stirred for 15 min and filtered. The line was washed with tetrahydrofuran (7 L) and the solvent was removed by distillation under reduced pressure at 20-25 ⁰C to a residual volume of 30 L. Isopropyl acetate (96 L) was added to obtain a solution of the title compound of formula I, which contains a small amount of impurities (mainly side products from the previous reactions.) Removal of the solvent from a sample yields a substantially amorphous solid.

The solution with the crude product was used for the direct preparation of the hemi-tartrate and simultaneously for the purification of the free base via the hemi-tartrate through crystallization from suitable solvents.

Example 5: Preparation of the hemi-tartrate of formula IV from crude free base of formula I

Crude product according to Example l(f) (4.3 kg) was dissolved at 45 ⁰C in ethanol (23 L). A solution of (+)-L-tartaric acid (0.58 kg) in ethanol was added at 45 ⁰C and the line was washed with 6 L of ethanol. The solution was stirred for 20 min (formation of solid precipitate) and the slurry was cooled to 35 ⁰C over 30 min. The slurry was stirred at this temperature for 1 hour and then cooled to -5 ⁰C. After 14 hours stirring at this temperature, the product was centrifuged and washed with 2 portions of ethanol (2 x 4 L). The wet cake was dried at 45 ⁰C for 80 hours yielding 3.3 kg of product (85%, based on tartaric acid). PXRD of the product revealed that polymorph A was formed.

Patent

WO2014085362A1.

CN101031548A

CN101035759A

CN102153505A

CN1816524A

US2008280886A1.

WO0144191

PATENT

WO-2016141003

Scheme 4:

The reaction depicted in Scheme 4 can be carried out in a suitable organic solvent such as acetone at rather mild conditions (e.g.40-50°C). If necessary, the R¹ substituent may subsequently be converted to an isobutoxy group to obtain Pimavanserin or a salt thereof.

An overview about certain processes for preparation of Pimavanserin is shown in Scheme 5 below.

Scheme 5:

Compound A L-Tartaric acid

Hemi-tartrate salt *Compound A is Pimavanserin

Scheme 10:

^{Compound 1 Compound 2 Pimavanserin}

Scheme 13:

An overview about synthetic routes to Pimavanserin via Compound XVI is shown in the following Scheme 14:

Scheme 14:

Example 16: Preparation of hemi-tartrate salt of Pimavanserin

To a 25 mL seal tube, equipped with a stir bar, was charged 344.4 mg of the above crude PMV (1.0 mmol in theory), 75 mg of L-tartaric acid (FW: 150.09, 0.5 mmol, 0.5 equiv.), and 7 mL (16.4 vol.) of absolute ethanol. The tube was sealed and heated to 70°C to afford a clear solution, then cooled down gradually to room temperature. The product precipitated, and the batch was further cooled down to 0-5°C and stirred at this temperature for 0.5 hour. The product was collected by vacuum filtration, and the filter cake was washed with 2 × 1 mL (2.3 vol.) of EtOH. The product was dried in the Buchner funnel under vacuum overnight, affording 177.6 mg of salt, representing a 35.4% yield in 99.6 A% purity. 1H NMR (CDCl₃, 400 MHz): δ = 1.01 (d, J = 6.4 Hz, 6 H), 1.79-1.82 (m, 2H), 2.02-2.19 (m, 3H), 2.63 (brs, 5H), 3.38-3.47 (m, 2H), 3.67 (d, J = 6.4 Hz, 2H), 4.25 (d, J = 4.8 Hz, 2H), 4.32 (s, 1H), 4.38 (s, 2H), 4.58 (brs, 2H), 6.77 (d, J = 8.0 Hz, 2H), 6.95-6.99 (m, 4H), 7.17 (d, J = 7.2 Hz, 2H).

Example 21: Preparation of Pimavanserin via compound V as dihydrochloride salt

Step 1: Preparation of N-(4-fluorobenzyl)-1-methylpiperidin-4-amine dihydrochloride (Compound V x 2HCl)

The reaction was performed in 300 mL reactor. The reactor was purged with N₂, then Argon. 4-Fluorobenzylamine (10 g; 80 mmol, 1.0 eq) was dissolved in dry MeCN (100 mL), then 1-methylpiperidin-4-one (10.9 g; 96 mmol, 1.2 eq) was added and the reaction mixture was stirred at ambient temperature for 18h. Then, the reaction mixture was cooled to 0°C and 25.4 g of NaBH(OAc)₃ (25.4 g; 120 mmol, 1.5 eq) was added in portions over 20 min and the reaction was allowed to stir to room temperature. After 1h, the reaction was quenched by the addition of 200 ml of water, pH was adjusted to 2 with 5M HCl and then extracted using 3 x 250 mL of DCM. Basification of the aqueous layer to pH 9.5 with 30% sol. NaOH and extraction 3 x 300 ml of DCM followed. The organic layers were collected and dried over anh. Na₂SO₄, filtered and evaporated to dryness yielding 17.24 g (92%) of oily product, N-(4-fluorobenzyl)-1-methylpiperidin-4-amine (Compound V).

To a 250 mL, three necked, round bottom flask, equipped with a stir bar and thermometer, N-(4-fluorobenzyl)-1-methylpiperidin-4-amine (10 g; 0.045 mol) and DCM (50 mL) were charged and cooled to 10-15 °C. To the resulting solution, 5-6 N HCl in 2-PrOH (3 equiv., 0.135 mmol) was added dropwise over 25 min., white crystals formed, and the solution then cooled to 0-5 °C for 2 hours. Crystals were filtered off, washed with 50 mL of DCM, dried at 50°C/10 mbar for 10 hours yielding 12.8 g (96.4%) of N-(4-fluorobenzyl)-1-methylpiperidin-4-amine dihydrochloride (Compound V x 2HCl).

Step 2: Preparation of 4-isobutoxybenzaldehyde (Compound XIII)

4-Hydroxybenzaldehyde (10 g; 0.082 mol), potassium carbonate (33.95 g; 0.246 mol) and potassium iodide (1.36 g; 0.008 mol) were suspended in N,N-dimethylformamide (50 mL). Isobutyl bromide (26.7 mL; 0.246 mol) was added and the reaction was heated at 70°C under nitrogen for 3 hours. The reaction was cooled down, diluted by using 150 mL of water and extracted by using 300 mL of ethyl acetate. The organic layer was extracted five times by using 150 mL of 10% NaCl solution, dried under Na₂SO₄, filtered and concentrated which resulted in 14.3 g (98%) of yellow oily product of 4-isobutoxybenzaldehyde

(Compound XIII).

Step 3: Preparation of (4-isobutoxyphenyl)methanamine hydrochloride (Compound XI x HCl)

[0142] To a solution of 4-isobutoxybenzaldehyde (Compound XIII) (19.9 g; 0.112 mol) in methanol (90 mL), Raney nickel (6 g) and 7N methanol ammonia solution (90 mL) were added. The reaction mixture was stirred under hydrogen atmosphere (0.5 bar) at 10-15°C for 24 hours. The reaction solution was filtered through Celite to remove the catalyst. Methanol was distilled off and toluene (500 mL) was added. The solution was concentrated to 250 mL and 5-6 N HCl in 2-PrOH (30 mL; 0.15 mol) was added dropwise at ambient temperature. The resulting suspension was then cooled to 5 °C and stirred for additional 2 hours. Crystals were filtered off, washed with 60 mL of toluene, dried at 50°C/10 mbar for 10 hours yielding 20.88 g (86.7%) of (4-isobutoxyphenyl)methanamine hydrochloride (Compound XI x HCl). The product was analyzed by PXRD– form I was obtained, the PXRD pattern is shown in Figure 3.

Step 4: Option 1: Preparation of 1-(4-fluorobenzyl)-3-(4-isobutoxybenzyl)-1-(1-methylpiperidin-4-yl)urea (Pimavanserin

Part a: Preparation of Compound VI-a:

To a 250 mL, three necked, round bottom flask, equipped with a stir bar, condenser and thermometer, (4-isobutoxyphenyl)methanamine hydrochloride (Compound XI x HCl) (5 g, 0.023 mol), CDI (6.01 g; 0.037 mol) and acetonitrile (40 mL) were charged. The resulting solution was stirred for 1 h at 65-70 °C and monitored by HPLC until full conversion to Compound VI-a.

Part b: Preparation of Pimavanserin:

N-(4-fluorobenzyl)-1-methylpiperidin-4-amine (Compound V) (7.73 g; 0.035 mol) was added to Compound VI-a obtained above. After 2h, complete conversion was observed. Upon completion, the reaction solution was cooled to 50 °C and water was added dropwise in a 1:3 ratio (120 mL). After addition of a whole amount of water, crystals were formed and suspension was allowed to cool to ambient temperature. The crystals were filtered off, washed with 2 x 40 mL solution of CH₃CN:H₂O 1:3, then 40 mL of water, dried at 45°C/10 mbar for 10 hours yielding 9.35 g (94.4%) of 1-(4-fluorobenzyl)-3-(4-isobutoxybenzyl)-1-(1-methylpiperidin-4-yl)urea (Pimavanserin).

Step 4– option 2: Preparation of 1-(4-fluorobenzyl)-3-(4-isobutoxybenzyl)-1-(1-methylpiperidin-4-yl)urea (Pimavanserin)

Part a: Preparation of Compound VI-a:

To a 500 mL, three necked, round bottom flask, equipped with a stir bar, condenser and thermometer, (4-isobutoxyphenyl)methanamine hydrochloride (Compound XI x HCl) (10 g; 0.046 mol), CDI (11.28 g; 0.07 mol) and acetonitrile (100 mL) were charged. The resulting solution was stirred for 1 h at 65-70 °C and monitored by HPLC until full conversion to Compound VI-a.

Part b: Preparation of Pimavanserin:

[0146] The reaction solution containing Compound VI-a obtained above was cooled to 30°C and N-(4-fluorobenzyl)-1-methylpiperidin-4-amine dihydrochloride (Compound V x 2HCl) (20.53 g; 0.07 mol) and K₂CO₃ (9.61 g; 0.07 mol) were added. The reaction mixture was heated to 65-70 °C and stirred for next 18 hours. Upon completion, the reaction solution was cooled to 50 °C, pH of solution was adjusted to 10.5 with 6N NaOH solution, and water was added dropwise in ratio 1:3 (300 mL). After addition of a whole amount of water, crystals were formed, and suspension was allowed to cool to ambient temperature, and then cooled on ice-bath (0-5°C) for 1.5 hour. The crystals were filtered off, washed with 2 x 100 mL solution of CH₃CN:H₂O 1:3, then 100 mL of water, dried at 45°C/10 mbar for 10 hours yielding 18.797 g (95.6%) of 1-(4-fluorobenzyl)-3-(4-isobutoxybenzyl)-1-(1-methylpiperidin-4-yl)urea (Pimavanserin).

Example 26: One pot preparation of Pimavanserin (without isolation of Compound 1)

Step 1: Preparation of 2-(4-isobutoxyphenyl)acetic acid

To a 250 mL, 3 neck, round bottom flask, equipped with thermocouple and nitrogen sweep, was charged 10 g of 4-hydroxy phenyl acetic acid (Molecular weight (FW): 152.15, 65.7 mmol, 1.0 equiv.), 30 g of potassium carbonate (FW: 138.21, 216.8 mmol, 3.3 equiv.), 1.1 g of potassium iodide (KI, FW: 166, 6.57 mmol, 0.1 equiv.), followed by 100 mL (10 vol.) of DMF. After stirring for 5 minutes at room temperature, 15.7 mL of isobutyl bromide (FW: 137.02, 144.6 mmol, 2.2 equiv.) was charged into the batch. The mixture was then heated to 75°C and kept stirring at the same temperature for 2 days until no limited starting material remaining as determined by HPLC. The reaction was cooled down to room temperature, and quenched by charging with 100 mL of deionized (DI) water. The pH of the reaction mixture was adjusted to less than 1 by charging 100 mL of 2N HCl. The product was extracted with 150 mL of ethyl acetate. After partitioning, the upper organic layer was washed with additional 100 mL of DI water, concentrated to dryness on the rotary evaporator under vacuum. The residue was dissolved in 100 mL each of THF (10 vol) and DI water (10 vol). After charging 20 g of lithium hydroxide, the mixture was heated to reflux for 3 hours until complete reaction. The batch was cooled to room temperature, concentrated on rotary

evaporator to remove THF. The residue was acidified with 300 mL of 2N HCl and 45 mL of 6N HCl aqueous solution until pH <1. The product was extracted with 2×250 mL of methylene chloride, dried over sodium sulfate, and filtered on Buchner funnel. The filtrate was concentrated to dryness on rotary evaporator under vacuum to afford 10.18 g of 2-(4-isobutoxyphenyl)acetic acid, representing a 74.4% yield in 98.5 A% purity. ¹H NMR (d₆-DMSO, 400 MHz): δ = 0.97 (d, J = 6.8 Hz, 6 H), 1.96-2.02 (m, 1H), 3.47 (s, 2H), 3.71 (d, J = 6.4 Hz, 2H), 6.86 (d, J = 8.8 Hz, 2H), 7.14 (d, J = 8.8 Hz, 2H).

Step 2: Preparation of Pimavanserin

To a 50 mL, single neck, round bottom flask, equipped with thermocouple and nitrogen sweep, was charged 333.2 mg of 2-(4-isobutoxyphenyl)acetic acid (FW: 208.25, 1.6 mmol, 1.0 equiv.), 311.3 mg of CDI (FW: 162.15, 1.92 mmol, 1.2 equiv.), and 3.3 mL of CH₃CN (10 vol.). After stirring at room temperature for 1 hour, this was charged 139 mg (FW: 69.5, 2.0 mmol, 1.25 equiv.) of NH₂OH^.HCl and stirred for additional 15-18 hours at room temperature. Additional 518.9 mg of CDI (FW: 162.15, 3.2 mmol, 2.0 equiv.) was charged and the batch turned from a slurry to a clear solution again. This was followed by charging a solution of 334 mg of Compound V (FW: 222.3, 1.5 mmol, 0.94 equiv.), and heating up to 60 ^oC. The reaction was stirred at this temperature for approximately 5 hour before cooling back to room temperature. The reaction was quenched with 20 mL of DI water, and concentrated on rotary evaporator to remove acetonitrile. The aqueous residue was diluted with 40 mL of ethyl acetate, and washed with 2×20 mL of brine. The organic phase was concentrated to dryness on rotary evaporator under vacuum. The residue was purified by chromatography (160 g RediSep Alumina column), eluting with 0-5% of methanol in dichloromethane to afford 305 mg of Pimavanserin, representing a 47.6% yield in 99.3 A% purity.¹H NMR (CDCl₃, 400 MHz): δ = 1.01 (d, J = 6.8 Hz, 6 H), 1.62-1.73 (m, 4H), 2.03-2.09 (m, 3H), 2.25 (s, 3H), 2.84-2.87 (m, 2H), 3.68 (d, J = 6.4 Hz, 2H), 4.27-4.34 (m, 5H), 4.45-4.48 (m, 1H), 6.67-6.79 (m, 2H), 6.99-7.02 (m, 4H), 7.16-7.27 (m, 2H). HRMS-ESI (m/z): [M+1]⁺ Calcd for C₂₅H₃₅F₁N₃O₂: 428.2708; found 428.2723.

Example 27: Preparation of Pimavanserin (with isolation of Compound 1)

Step 1: Preparation of Compound 1

[0156] To a 100 mL, single neck, round bottom flask, equipped with thermocouple and nitrogen sweep, was charged 1 g of Compound XV (FW: 208.25, 4.8 mmol, 1.0 equiv.), 934.0 mg of CDI (FW: 162.15, 5.76 mmol, 1.2 equiv.), followed by 10 mL (10 vol.) of acetonitrile. After stirring for 45 minutes at room temperature, 417 mg of NH₂OH.HCl (FW: 69.5, 6.0 mmol, 1.25 equiv.) was charged into the batch. The mixture was kept stirring at the ambient temperature overnight and turned into a thick slurry. HPLC determined 1.6 A% of starting material remaining. The batch was diluted with 6 mL of acetonitrile (6 vol.) and 16 mL (16 vol.) of DI water, and cooled down to 0-5 ºC. After stirring at the same temperature for additional 1 hour, the batch was filtered on the Buchner funnel. The filter cake was washed with 2×10 mL (10 vol.) of DI water, and dried in the funnel under vacuum overnight to afford 774.1 mg of hydroxamic acid Compound 1, representing a 72% yield in 99.6 A% purity. ¹H NMR (CDCl₃, 400 MHz): δ = 0.96 (d, J = 6.8 Hz, 6 H), 1.95-2.02 (m, 1H), 3.19 (s, 2H), 3.70 (d, J = 6.4 Hz, 2H), 6.85 (d, J = 8.4 Hz, 2H), 7.14 (d, J = 8.4 Hz, 2H), 8.80 (s, 1H), 10.61 (s, 1H).

Step 2: Synthesis of Pimavanserin

[0157] To a 50 mL sealed tube, equipped with nitrogen sweep, was charged 250 mg of compound 1 (FW: 223.27, 1.12 mmol, 1.0 equiv.), 217.9 mg of CDI (FW: 162.15, 1.34 mmol, 1.2 equiv.), and 1.7 mL of acetonitrile (6.8 vol.). After stirring at room temperature for 40 minutes, the batch was heated to 60 ^oC and kept stirring at the same temperature for additional 10 minutes. This was followed by charging 373.5 mg of Compound 3 (FW: 222.3, 1.68 mmol, 1.5 equiv.). The container of Compound V was rinsed with 0.5 mL (2 vol.) of acetonitrile, and the wash was combined with the batch. The reaction was monitored by HPLC and complete in 2 hours. The batch was cooled down to room temperature, diluted with 5 mL (20 vol.) of ethyl acetate, which was washed with 3×5 mL (20 vol.) of DI water. After partitioning, the upper organic layer was concentrated to dryness on rotary evaporator. The residue was re-dissolved into 3 mL (12 vol.) of ethyl acetate after heating up to reflux to afford a slightly milky solution. This was charged with 12 mL (48 vol.) of heptane, and cooled down to 0-5^oC. The batch was kept stirring at the same temperature for 1 hour and filtered on a Buchner funnel. The filter cake was washed with 2×5 mL (20 vol.) of heptane, and dried in the funnel with a nitrogen sweep for 1 hour to afford 270.8 mg of Pimavanserin as a white solid, representing a 56.6% yield in 98.8 A% purity. ¹H NMR (CDCl₃, 400 MHz): δ = 1.01 (d, J = 6.8 Hz, 6 H), 1.62-1.73 (m, 4H), 2.03-2.09 (m, 3H), 2.25 (s, 3H), 2.84-2.87 (m, 2H), 3.68 (d, J = 6.4 Hz, 2H), 4.27-4.34 (m, 5H), 4.45-4.48 (m, 1H), 6.67-6.79 (m, 2H), 6.99-7.02 (m, 4H), 7.16-7.27 (m, 2H). HRMS-ESI (m/z): [M+1]⁺ Calcd for C₂₅H₃₅F₁N₃O₂: 428.2708; found 428.2723.

Example 34: Preparation of Pimavanserin from Compound 2

[0169] To a 25 mL, three neck, round bottom flask, equipped with a stir bar, condenser and thermocouple, Compound 2, 0.210 g, was charged (FW: 249.26, 0.84 mmol, 1.0 equiv.). This was followed 3 mL of acetonitrile, anhydrous, 99.8%. The mixture was stirred at 60°C for 4 h. Then, to the reaction mixture, Compound V, 0.375 g (FW: 222.30, 1.69 mmol, 2.0 equiv.), was added. After 1h, complete conversion was observed. The reaction was diluted with EtOAc (20 mL) and washed twice with a saturated solution of NH4Cl (2 x 15 mL), then H2O (10 mL) and finally with a saturated NaCl solution (10 mL). The organic layer was dried over anh. sodium sulfate, filtered and concentrated under partial vacuum to about 5 mL of EtOAc. To this solution, n-heptane (10 ml) was added with vigorous stirring, in a dropwise manner, over half an hour. A white precipitate was formed, followed by filtration and drying in vacuum at 45°C for 3h, affording 0.188 g of Pimavanserin. HPLC-MS (m/z) [M+1]+ 428.2; 1H NMR (CDCl3, 400 MHz): δ = 1.01 (d, J = 6.7 Hz, 6 H), 1.68-1.77 (m, 4H), 2.03-2.10 (m, 3H), 2.30 (s, 3H), 2.91-2.97 (m, 2H), 3.67(d, J = 6.7 Hz, 2H), 4.27 (d, J = 5.4 Hz, 2H), 4.31-4.43 (m, 3H), 4.50 (brt, J = 5.5 Hz, 1H), 6.74-6-79 (m, 2H), 6.95-7.05 (m, 4H), 7.14-7.22 (m, 2H).

Example 38: Preparation of Pimavanserin from Compound and Compound V x 2HCl

[0179] 250 mL reactor was charged with N-hydroxy-2-(4-isobutoxyphenyl)acetamide (Compound 1) (10 g, 0.045 mol), CDI (10.53 g, 0.076 mol) and 100 mL of MeCN, p.a. The resulting solution was stirred for 1.5 h at 60-65 °C and monitored by HPLC. Upon full conversion to the corresponding isocyanate, reaction solution was cooled to 35 °C and N-(4- fluorobenzyl)-1-methylpiperidin-4-amine dihydrochloride (Compound V x 2HCl) (22.48 g, 0.065 mol) and K₂CO₃ (6.19 g, 0.045 mol) were added. Reaction mixture was heated up to 60-65 °C and stirred for 6 hours and followed by 17 h at ambient temperature.

[0180] Upon completion, the reaction solution was cooled to 20 °C and water was added dropwise in ratio 1:3 (300 mL) with adjustment of pH to 11 with 6N NaOH solution. After addition of whole amount of water, crystals were formed and suspension was stirred at 20 °C for 2 h and 0-5°C for next 2 hour. Crystals were filtered off, washed with 2 x 100 mL solution of MeCN:H₂O 1:3, then 100 mL of H₂O, dried at 30°C/10 mbar for 24 hours yielding 17.56 g (91.7%) of Pimavanserin.

PAPER

Bioorg. Med. Chem. Lett. 2015, 25, 1053–1056.

Bioorganic & Medicinal Chemistry Letters

Volume 25, Issue 5, 1 March 2015, Pages 1053–1056

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THURSDAY Oct. 31, 2013 — Many people living with Parkinson’s disease suffer from hallucinations and delusions, but an experimental drug might offer some relief without debilitating side effects.

READ ALL AT

http://www.drugs.com/news/new-shows-early-promise-treating-parkinson-s-psychosis-48630.html

The drug — pimavanserin — appears to significantly relieve these troubling symptoms, according to the results of a phase 3 trial to test its effectiveness.

Pimavanserin (ACP-103) is a drug developed by Acadia Pharmaceuticals which acts as an inverse agonist on the serotonin receptor subtype 5-HT_2A, with 40x selectivity over 5-HT_2C, and no significant affinity or activity at 5-HT_2B or dopamine receptors.^[1] As of September 3 2009, pimavanserin has not met expectations for Phase III clinical trials for the treatment of Parkinson’s disease psychosis,^[2] and is in Phase II trials for adjunctive treatment of schizophrenia alongside an antipsychotic medication.^[3] It is expected to improve the effectiveness and side effect profile of antipsychotics.^[4][5][6]

3-D MODEL OF DRUG PIMAVANSERIN, THE DEVELOPMENT OF WHICH HAS BEEN EXPEDITED BY THE FDA

External links

• Nuplazid (pimavanserin) Official Site

References

1. ^ Jump up to:^{a b c} Friedman, JH (October 2013). “Pimavanserin for the treatment of Parkinson’s disease psychosis”. Expert Opinion on Pharmacotherapy. 14 (14): 1969–1975.doi:10.1517/14656566.2013.819345. PMID 24016069.
2. ^ Jump up to:^{a b c} “Nuplazid (pimavanserin) Tablets, for Oral Use. U.S. Full Prescribing Information” (PDF). ACADIA Pharmaceuticals Inc. Retrieved 1 May 2016.
3. Jump up^ ACADIA Pharmaceuticals. “Treating Parkinson’s Disease – Clinical Trial Pimavanserin – ACADIA”. Archived from the original on February 25, 2009. Retrieved 2009-04-11.
4. Jump up^ “ACADIA Announces Positive Results From ACP-103 Phase II Schizophrenia Co-Therapy Trial” (Press release). ACADIA Pharmaceuticals. 2007-03-19. Retrieved 2009-04-11.
5. Jump up^ Gardell LR, Vanover KE, Pounds L, Johnson RW, Barido R, Anderson GT, Veinbergs I, Dyssegaard A, Brunmark P, Tabatabaei A, Davis RE, Brann MR, Hacksell U, Bonhaus DW (Aug 2007). “ACP-103, a 5-hydroxytryptamine 2A receptor inverse agonist, improves the antipsychotic efficacy and side-effect profile of haloperidol and risperidone in experimental models”. The Journal of Pharmacology and Experimental Therapeutics. 322 (2): 862–70. doi:10.1124/jpet.107.121715.PMID 17519387.
6. Jump up^ Vanover KE, Betz AJ, Weber SM, Bibbiani F, Kielaite A, Weiner DM, Davis RE, Chase TN, Salamone JD (Oct 2008). “A 5-HT2A receptor inverse agonist, ACP-103, reduces tremor in a rat model and levodopa-induced dyskinesias in a monkey model”. Pharmacology, Biochemistry, and Behavior. 90 (4): 540–4. doi:10.1016/j.pbb.2008.04.010. PMC 2806670.PMID 18534670.
7. Jump up^ Abbas A, Roth BL (Dec 2008). “Pimavanserin tartrate: a 5-HT2A inverse agonist with potential for treating various neuropsychiatric disorders”. Expert Opinion on Pharmacotherapy. 9 (18): 3251–9.doi:10.1517/14656560802532707. PMID 19040345.
8. Jump up^ Meltzer HY, Elkis H, Vanover K, Weiner DM, van Kammen DP, Peters P, Hacksell U (Nov 2012). “Pimavanserin, a selective serotonin (5-HT)2A-inverse agonist, enhances the efficacy and safety of risperidone, 2mg/day, but does not enhance efficacy of haloperidol, 2mg/day: comparison with reference dose risperidone, 6mg/day”. Schizophrenia Research. 141 (2-3): 144–152. doi:10.1016/j.schres.2012.07.029. PMID 22954754.
9. Jump up^ “ACADIA Pharmaceuticals Receives FDA Breakthrough Therapy Designation for NUPLAZID™ (Pimavanserin) for Parkinson’s Disease Psychosis”. Press Releases. Acadia. 2014-09-02.
10. Jump up^ “Press Announcements — FDA approves first drug to treat hallucinations and delusions associated with Parkinson’s disease”. U.S. Food and Drug Administration. Retrieved1 May 2016.

NUPLAZID contains pimavanserin, an atypical antipsychotic, which is present as pimavanserin tartrate salt with the chemical name, urea, N-[(4-fluorophenyl)methyl]-N-(1-methyl-4-piperidinyl)-N’-[[4-(2- methylpropoxy)phenyl]methyl]-,(2R,3R)-2,3-dihydroxybutanedioate (2:1). Pimavanserin tartrate is freely soluble in water. Its molecular formula is (C₂₅H₃₄FN₃O₂)₂•C₄H₆O₆ and its molecular weight is 1005.20 (tartrate salt). The chemical structure is:

 

The molecular formula of pimavanserin free base is C₂₅H₃₄FN₃O₂ and its molecular weight is 427.55.

NUPLAZID tablets are intended for oral administration only. Each round, white to off-white, immediaterelease, film-coated tablet contains 20 mg of pimavanserin tartrate, which is equivalent to 17 mg of pimavanserin free base. Inactive ingredients include pregelatinized starch, magnesium stearate, and microcrystalline cellulose. Additionally, the following inactive ingredients are present as components of the film coat: hypromellose, talc, titanium dioxide, polyethylene glycol, and saccharin sodium.

Pimavanserin

Systematic (IUPAC) name
N-(4-fluorophenylmethyl)-N-(1-methylpiperidin-4-yl)-N’-(4-(2-methylpropyloxy)phenylmethyl)carbamide
Clinical data
Trade names	Nuplazid
Routes of administration	Oral (tablets)
Legal status
Legal status	US: ℞-only
Pharmacokinetic data
Protein binding	94–97%[1]
Metabolism	Hepatic (CYP3A4, CYP3A5,CYP2J2)[2]
Biological half-life	54–56 hours[1]
Identifiers
CAS Number	706779-91-1  706782-28-7 (tartrate)
ATC code	None
PubChem	CID 10071196
DrugBank	DB05316
ChemSpider	8246736
UNII	JZ963P0DIK
KEGG	D08969
ChEBI	CHEBI:133017
ChEMBL	CHEMBL2111101
Synonyms	ACP-103
Chemical data
Formula	C25H34FN3O2
Molar mass	427.553 g/mol
SMILES[hide] CC(C)COc3ccc(cc3)CNC(=O)N(C(CC2)CCN2C)Cc(cc1)ccc1F

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//////////Pimavanserin, FDA 2016,  Nuplazid®,  Acadia , Breakthrough Therapy, serotonin 2A receptor (5-HT_2AR) inverse agonist, priority review