Pharmacokinetic and Tolerability Comparison of Sustained and Immediate Release Oral Formulations of Nifedipine Tablet Formulations: A Single-Dose, Randomized, Open-Label, Two-Period, Two-Way Crossover Study in Healthy, Fasting Egyptian Male Volunteers

Abstract Nifedipine is one of calcium channel blockers that commonly used clinically to treat hypertension and angina in Egyptian patients. A sustained-release (SR) formulation of nifedipine is available in the Egyptian community and administered twice daily. This study aimed to to compare the pharmacokinetics and safety profiles of a 20 mg SR and IR (immediate release) formulation of nifedipine after single-dose administration in healthy Egyptian subjects. Randomized, crossed open-label two- way clinical trial, in 16 healthy adult volunteers, of 24.75±5.20 years, with BMI 23.26±1.756 were assessed. Blood samples were collected at predefined times for 48 h and analyzed for Nifedipine plasma concentrations using validated reversed phase liquid chromatography method with ultraviolet detection. Pharmacokinetics was determined using non- compartmental model pharmacokinetics and analyzed using one-way ANOVA (P≤0.05). Following a single oral administration, SR formulation had a lower Cmax, compared to IR formulation (54.46±17.75 , 107.45±29.85 ng/mL, respectively), and Tmax was significantly longer (2.97 vs. 1.13 h) for the SR and IR formulation, respectively. There was no significant difference between the SR and the IR formulations for AUC0–last and AUC0-∞ (326.7±98.28 vs. 309.27±105.53 ng·h·mL−1 and 380.9 ± 105.24 vs. 334.36±108.1 ng·h·mL−1, respectively). SR formulation of nifedipine showed similar pharmacokinetics to the IR Formulation (F%=1.049), but it additionally allows a less frequent administration. Therefore, The nifedipine SR and IR formulations were well tolerated and displayed comparable safety profiles.