Formulation dependent pharmacokinetics--does the dosage form matter for nifedipine?

Area of Science:

• Pharmacology
• Clinical Pharmacy
• Drug Formulation

Background:

• Nifedipine is a widely used calcium channel blocker for hypertension and angina.
• Different nifedipine formulations exist, including GITS, prolonged action (PA), and immediate-release capsules.
• Understanding the pharmacokinetic profiles of these formulations is crucial for optimizing therapeutic outcomes.

Purpose of the Study:

• To compare the pharmacokinetics of nifedipine GITS tablets against prolonged action tablets and capsules in healthy male subjects.
• To evaluate differences in absorption, peak concentration, and overall drug exposure among the tested nifedipine formulations.

Main Methods:

• An open-label, randomized, 3-way crossover study was conducted in 25 healthy male participants.
• Subjects received a single 60-mg dose of nifedipine GITS, or 20-mg nifedipine PA every 12 hours, or 10-mg nifedipine capsules every 8 hours.
• Plasma concentrations were measured over time to determine pharmacokinetic parameters like Cmax, Tmax, and AUC(infinity).

Main Results:

• Nifedipine capsules and PA tablets demonstrated significantly higher Cmax and AUC(infinity) compared to the GITS formulation (P=0.0001).
• The GITS formulation exhibited a significantly longer Tmax (15.0 hours) compared to capsules (0.7 hours) and PA tablets (1.7 hours) (P=0.001).
• A noticeable lag time of 2-3 hours was observed in plasma concentration profiles for the GITS formulation.

Conclusions:

• Nifedipine pharmacokinetics are markedly dependent on the drug formulation.
• The observed differences in Cmax, Tmax, and AUC(infinity) suggest distinct absorption and release characteristics for GITS, PA, and capsule formulations.
• These formulation-dependent pharmacokinetic variations may have significant clinical implications for nifedipine therapy.