Influence of nifedipine therapy on indocyanine green and oral propranolol pharmacokinetics.

Nine healthy adults were administered indocyanine green (ICG) 0.5 mg.kg-1 IV alone and after the administration of the following oral drugs: nifedipine 10 mg, propranolol 80 mg, propranolol 80 mg and nifedipine 10 mg, and propranolol 80 mg after nifedipine 10 mg every 8 h for 5 days. Heart rate and mean arterial blood pressure (MAP) were also determined. Nifedipine increased ICG clearance by 14% and decreased t1/2 by 26%. Propranolol decreased ICG clearance by 21% and increased t1/2 42%. Nifedipine and propranolol given together increased ICG clearance 63% and decreased t1/2 by 19%. All changes were statistically significant. Propranolol given after multiple doses of nifedipine did not change ICG kinetic parameters. Propranolol Cmax, tmax, oral clearance, and t1/2 did not change after nifedipine therapy. However, partial propranolol AUC values between 0-0.33, 0-0.5, 0-1.0 and 0-1.5 h were significantly larger after single and multiple doses of nifedipine indicating higher propranolol concentrations during the absorption phase. Heart rate and MAP did not change after nifedipine treatment. Similar declines in heart rate and MAP occurred after propranolol alone and propranolol after single and multiple doses of nifedipine.