S-Ambes Mechanism of Action





Full Prescribing Info
Pharmacology: Pharmacodynamics: S(-)amlodipine, the chirally pure form of amlodipine is a calcium channel antagonist belonging to the dihydropyridine class. The S(-)isomer of amlodipine is found to possess greater pharmacological effects than R(+)amlodipine. S(-)amlodipine is 1000 times more potent than the R(+)isomer in binding to the dihydropyridine receptor. In humans, the dominant effects of amlodipine are consequent to vasodilation. S(-)amlodipine lowers peripheral vascular resistance without causing a reflex tachycardia. It is effective as a once daily dosage in the control of hypertension.
SESA (Safety and efficacy of S(-)amlodipine) study was designed to evaluate the efficacy and tolerability of effects of S(-)amlodipine. This study involved 1859 patients with hypertension from 359 different centers across India. This study states that S(-)amlodipine has an excellent antihypertensive activity and is highly beneficial in all grades of hypertension with concomitant cardiovascular diseases like angina pectoris. The SESA study also enrolled 552 patients who were earlier treated with conventional amlodipine. Out of these, 314 patients presented with peripheral edema at the time of enrollment. When these patients were switched over to S(-)amlodipine, in 310 (98.72%) patients, edema was found to be completely resolved. These patients remained without edema thereafter. The findings of this study therefore state that S(-)amlodipine 2.5/5 mg was found to be effective and well tolerated in the treatment of hypertension and is an ideal switch over therapy for patients having peripheral edema with conventional amlodipine.
A randomized, comparative, single blinded, single centered, prospective and parallel group study was conducted to compare the efficacy and tolerability of racemic amlodipine 5 mg O.D to S(-)amlodipine O.D at the half its racemic dose (2.5 mg) in 108 patients with mild to moderate hypertension. The study observed that the mean SBP and DBP were significantly reduced from baseline in both the study groups at 2, 6 and 12 weeks (p<0.0001) proving the efficacy of both the study drugs in reduction of blood pressure to target level. This study also proves that S(-)amlodipine 2.5 mg is equally efficacious in reducing B.P compared to racemic amlodipine 5 mg as evidenced by other studies. Regarding the appearance of ankle edema which is the common adverse effect with calcium channel antagonist, the higher incidence of ankle edema with racemic amlodipine compared to S(-)amlodipine was found significantly.
An open non-comparative Post Marketing Surveillance (PMS) study to assess the efficacy and tolerability of S(-)amlodipine 2.5 / 5 mg in the treatment of hypertension was carried out in 1042 patients with hypertension from 121 centers across India. All patients were given either 2.5/5 mg of S(-)amlodipine (Asomex) depending upon the baseline BP values. Patients with history of MI, cerebrovascular accident, asthma, anemia, edema with earlier treatment and obesity were also included in the study. Results were analyzed by student's t-test. Reduction in the average SBP and DBP in S(-)amlodipine 2.5 and 5 mg group after 4 weeks of treatment was found to be statistically significant. The average SBP and DBP reduced from 161/99 mm Hg to 132/84 mm Hg in the 2.5 mg group (n=848); and from 180/107mm Hg to 138/86 mm Hg in the 5 mg group (n=194) after 4 weeks. Of the 247 patients, 243 (98.38%) reported resolution of edema after switching over from conventional amlodipine to Asomex. Only 21 patients reported mild side effects, such as vertigo, tachycardia, cough, headache, fever, difficulty in breathing and edema (1.15%). S(-)amlodipine 2.5 and 5 mg are effective and well tolerated in the treatment of hypertension and is an ideal switch over therapy for patients having peripheral edema with conventional amlodipine.
Pharmacokinetics: Administration of S(-)amlodipine 2.5 mg as a single dose in the fasting state produced maximum plasma concentration (Cmax) of 8.30 ± 1.071 ng/ml in 2.73 ± 0.88 hrs. (Tmax). Amlodipine is extensively (about 90%) converted to inactive metabolites via hepatic metabolism with 10% of the parent compound and 60% of the metabolites excreted in the urine. Ex vivo studies have shown that approximately 93% of the circulating drug is bound to plasma proteins in hypertensive patients. The mean AUC0-t value (t= 48 hrs.) of tablet S(-)amlodipine (2.5 mg) is 95.33 ± 14.45 ng.hr/ml. The AUC0-∞ value is recorded to be 140.91 ± 28.06 ng.hr/ml. The plasma elimination half-life of S(-)amlodipine has been found to be in the range of 14.62- 68.88 hrs.
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