R-verapamil: pharmacokinetics and effects on PR interval, blood pressure and heart rate. |
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Authors: | J H Ahmed J Godden P A Meredith H L Elliott |
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Affiliation: | University Department of Medicine and Therapeutics, Gardiner Institute, Western Infirmary, Glasgow. |
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Abstract: | 1. This study in healthy normotensive male volunteers investigated the pharmacokinetics and the effects on electrocardiographic PR interval, blood pressure and heart rate of single oral doses of the single isomer R-verapamil (250, 500 and 1000 mg) in comparison to placebo and 240 mg racemic verapamil. 2. After 500 and 1000 mg R-verapamil there were significant prolongations in PR interval, maximal at 1-2 h after dosing and coincident with peak plasma drug concentrations, but these were not significantly different from the maximum prolongation obtained with 240 mg racemic verapamil. 3. After 1000 mg R-verapamil there was a significant hypotensive effect, particularly on standing. 4. Single doses of 500 and 1000 mg R-verapamil produced peak plasma drug concentrations in the range 1000-3000 ng ml-1. If this concentration range is appropriate for adjuvant cancer chemotherapy it can be predicted that similar steady state concentrations will occur with a dosage regimen of 300 mg 3 times daily. |
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