SPL Set ID: 4a4d5b67-6ce7-4098-9324-f68084e800e4

Nifedipine is a drug belonging to a class of pharmacological agents known as the calcium channel blockers. Nifedipine is 3,5-pyridinedicarboxylic acid, 1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)-, dimethyl ester, C 17 H 18 N 2 O 6 , and has the structural formula: Nifedipine is a yellow powder, freely soluble in acetone; practically insoluble in water. It has a molecular weight of 346.3. Nifedipine extended-release tablet is formulated as a once-a-day controlled-release tablet for oral administration to provide 30, 60, or 90 mg of nifedipine. Each tablet contains 33 mg nifedipine to provide a 30 mg dose. Each tablet contains 66 mg nifedipine to provide a 60 mg dose. Each tablet contains 99 mg nifedipine to provide a 90 mg dose. Inert ingredients in the formulations are: ammonium hydroxide; black iron oxide; cellulose acetate; hydroxypropyl cellulose; propylene glycol; hypromellose; magnesium stearate; polyethylene glycol; polyethylene oxide; butylated hydroxytoluene; red ferric oxide; shellac; sodium chloride; titanium dioxide. FDA approved dissolution test specifications differ from USP. System Components and Performance Nifedipine extended-release tablet is similar in appearance to a conventional tablet. It consists, however, of a semipermeable membrane surrounding an osmotically active drug core. The core itself is divided into two layers: an “active” layer containing the drug, and a “push” layer containing pharmacologically inert (but osmotically active) components. As water from the gastrointestinal tract enters the tablet, pressure increases in the osmotic layer and “pushes” against the drug layer, releasing drug through the precision laser-drilled tablet orifice in the active layer. Nifedipine extended-release tablets are designed to provide nifedipine at an approximately constant rate over 24 hours. This controlled rate of drug delivery into the gastrointestinal lumen is independent of pH or gastrointestinal motility. Nifedipine extended-release tablets depends for its action on the existence of an osmotic gradient between the contents of the bi-layer core and fluid in the gastrointestinal tract. Drug delivery is essentially constant as long as the osmotic gradient remains constant, and then gradually falls to zero. Upon swallowing, the biologically inert components of the tablet remain intact during gastrointestinal transit and are eliminated in the feces as an insoluble shell. nif-str