Felodipine is a medication used in the management and treatment of essential hypertension. It is a member of the dihydropyridine class of calcium channel blockers. Reduction in blood pressure lowers the risk of cardiovascular morbidity and mortality.

General Properties and Specifications of Felodipine:
Appearance: Light yellow to yellow crystalline powder.
Solubility: freely soluble in acetone and methanol. Very slightly soluble in heptane. Insoluble in water.
Identification: by IR and by HPLC.
Assay: 98% to 101%
Residue on ignition: 0.1% maximum.
Loss on drying: 0.5% maximum.
Color of the solution 20mg/ml in methanol: < 0.2 absorbance.
Limit of Ethyl 3-Aminocrotanate: 0.15% maximum.
Methyl Benzylidene acetoacetate: 0.15% maximum.
Felodipine related compound A: 0.15% maximum.
Sum of dimethyl felodipine and diethyl felodipine: 1% maximum.
Any unspecified impurity: 0.1% maximum.
Total impurities: 1.5% maximum.
Residual solvent Isopropyl Alcohol: 5000 ppm maximum.
Particle size: D90 Less than 10 µm.
Relative Density: about 1.28
Melting Point: 145C literature.
Boiling Point: 472C literature.
Solubility: Practically insoluble in water.
Storage: At room temperature in light-resistant containers.

Felodipine USP Grade Specifications:
C18H19Cl2NO4 --- 384.25
3,5-Pyridinedicarboxylic acid 4-(2,3-dichlorophenyl)-1,4-dihydro-2,6-dimethyl-, ethyl methyl ester, (±)-;
(±)-Ethyl methyl 4-(2,3-dichlorophenyl)-1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate CAS 72509-76-3, 86189-69-7
UNII: OL961R6O2C

DEFINITION
Felodipine contains NLT 98.0% and NMT 101.0% of felodipine (C18H19Cl2NO4), calculated on the dried basis.

IDENTIFICATION
A. Infrared Absorption
B. The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.
Residue on Ignition: NMT 0.1%
Organic Impurities: To pass the test. Maximum 1.5%
Loss on Drying: Dry the sample at 105C for 3 h. Acceptance criteria: NMT 0.5%
Color of Solution: To pass the test.

Felodipine BP Ph Eur Grade:
C18H19Cl2NO4 --- 384.3 --- CAS 72509-76-3
Action and use: Calcium channel blocker.

DEFINITION
Ethyl methyl (4RS)-4-(2,3-dichlorophenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate.
Content: 99.0 per cent to 101.0 per cent (dried substance).

CHARACTERS
Appearance: White or light yellow, crystalline powder.
Solubility: Practically insoluble in water, freely soluble in acetone, in anhydrous ethanol, in methanol and in methylene chloride.

IDENTIFICATION
First identification: B
Second identification: A, C, D
A. Ultraviolet and visible absorption spectrophotometry.
B. Infrared absorption spectrophotometry.
C. Thin-layer chromatography
D. Ultraviolet and visible absorption spectrophotometry.

Solution S: Dissolve 1.00 g in methanol and dilute to 20.0 mL with the same solvent.
Appearance of solution: Solution S is clear.
Absorbance: Maximum 0.10, determined at 440 nm on solution S.
Related substances: To pass the test.
Loss on drying: Maximum 0.5 per cent, determined on 1.000 g by drying in an oven at 105C for 3 h.
Sulfated ash: Maximum 0.1 per cent, determined on 1.0 g.