Analysis of secondary care data to evaluate the clinical relevance of the drug-drug interaction between amlodipine and simvastatin.

BACKGROUND

Pharmacokinetic analyses revealed an increase in the bioavailability of simvastatin when co-administered with amlodipine [Nishio S et al. Hypertensin research 2005; Son H et al. Drug metabolism and pharmacokinetics 2014]. This may induce an increased risk of muscle toxicity for patients who receive this combination. So far, no in vivo data on the clinical relevance of this interaction exist. The objective of the present analysis was to determine the number of patients with concomitant treatment of amlodipine and simvastatin. Subsequently, the data was analyzed for the indication of muscular discomfort. Patients with combined prescription of amlodipine and another hydroxymethylglutaryl-CoA-reductase inhibitor except simvastatin or patients receiving simvastatin without amlodipine served as control groups.

METHODS

The present analysis used secondary data from the health insurance company AOK PLUS including information regarding diagnosis and drug prescriptions.

RESULTS

In total, 67.081 patients corresponding to 4.93% of the analyzed collective received a combined prescription of amlodipine and simvastatin. The absolute frequency increased continuously over time. Muscular discomfort was detected in a) 6.20% of the patients receiving amlodipine and simvastatin, b) 6.60% of the patients receiving amlodipine and another hydroxymethylglutaryl-CoA- reductase inhibitor and c) 8.04% of the patients with simvastatin only.

CONCLUSIONS

The present analysis shows an increasing trend of combined prescriptions of amlodipine and simvastatin. Evidence for simvastatin dose adaptation or therapy switch to another hydroxymethylglutaryl-CoA-reductase inhibitor, however, was not found. Muscular discomfort does not occur more often in patients with amlodipine and simvastatin compared to the two control groups. The results of the present analysis reveal no evidence for a clinically relevant interaction between amlodipine and simvastatin.