How long will it take for amlodipine to lower my blood pressure?

Oral administration of amlodipine produces peak plasma concentrations after 6 to 12 hours.^1-4

The pharmacokinetics of amlodipine were studied among healthy male volunteers in a double-blind parallel group comparison.⁵ Oral administration of 10 mg resulted in a mean systemic availability of 64% and a mean plasma half-life of 36 hours. Oral administration of 15 mg resulted in steady state plasma drug concentration after the seventh dose. Dosage of 15 mg led to an accumulation of approximately three-fold when compared to 10 mg dosage, and a mean half-life of 45 hours.^2,5 Absorption of amlodipine was detected within 0.5-1 hour however, peak concentration was not reached until a mean of approximately eight hours.⁵ Based on this and similar studies, it has been suggested that oral amlodipine should be initiated at a dosage of 5 mg daily and increased to 10 mg daily if the desired therapeutic effect has not been achieved after two weeks.²

Similarly, Burges et al. reported that amlodipine reaches peak plasma concentrations eight hours after administration, and steady-state concentration is reached after seven to nine doses of amlodipine.³

Donnelly et al. studied the effects of amlodipine in six men and six women ages 25 to 64 years with hypertension (baseline blood pressure range 160/90 – 210/115 mmHg).⁶  After six weeks without antihypertensive therapy, average participant blood pressure was 175/103 mmHg. Participants began a three-week placebo period followed by a six-week treatment with 5mg amlodipine. There was a significant reduction in blood pressure at 24 and 48 hours after the first dose of amlodipine (p<0.001).⁶ After the first dose, average supine blood pressure was 7/1 mmHg less tin the amlodipine group than in the placebo group at 24 hours, and 11/4 mmHg less at 48 hours.⁶ After six weeks of treatment there was a significant reduction in baseline blood pressure (p<0.001).⁶ These findings suggest that amlodipine causes significant reductions in blood pressure within 24-48 hours after the first dose and the blood pressure lowering effects are maintained over time once the drug reaches steady state.

^References

1. FDA. Amlodipine Besylate. Drugs at FDA 2007; http://www.accessdata.fda.gov/drugsatfda_docs/label/2007/019787s042lbl.pdf.
2. Murdoch D, Heel RC. Amlodipine. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in cardiovascular disease. Drugs. Mar 1991;41(3):478-505.
3. Burges R. Amlodipine: a once daily calcium antagonist. J. Hum. Hypertens. 1991;5:49-54.
4. Meredith PA, Elliott HL. Clinical pharmacokinetics of amlodipine. Clin. Pharmacokinet. Jan 1992;22(1):22-31.
5. Faulkner J, McGibney D, Chasseaud L, Perry J, Taylor I. The pharmacokinetics of amlodipine in healthy volunteers after single intravenous and oral doses and after 14 repeated oral doses given once daily. British journal of clinical pharmacology. 1986;22(1):21-25.
6. Donnelly R, Meredith PA, Miller SH, Howie CA, Elliott HL. Pharmacodynamic modeling of the antihypertensive response to amlodipine. Clin Pharmacol Ther. Sep 1993;54(3):303-310.