Drug Interactions with Antihypertensives

Hypertension is remarkably prevalent, affecting an estimated 1.13 billion people worldwide. It often requires the use of multi-drug regimens and is commonly associated with a myriad of other comorbidities which increase medication use. The pervasive use of antihypertensive medications combined with the presence of polypharmacy in many hypertensive patients results in significant risk of drug interactions. This review will summarize the relevant literature to assist clinicians in mitigating drug interaction risks when prescribing antihypertensives. Pharmacokinetic interactions affect drug disposition in the body and can occur at the steps of absorption, distribution, metabolism, or elimination of involved medications. Data has established the calcium channel blockers, namely, diltiazem and verapamil, as potent inhibitors of CYP3A4, and the majority of significant drug interactions involving antihypertensives are attributable to these two agents. Although less common, pharmacokinetic drug interactions with other antihypertensive classes have also been identified. Pharmacodynamic drug interactions with antihypertensives lead to synergy or antagonism of blood pressure lowering effects and can increase or mitigate adverse effects depending on the agents involved. Knowledge is emerging about drug-induced phenoconversion, a phenomenon whereby a drug interaction results in a drug metabolizing phenotype that is different than that predicted by an individual’s genotype. Antihypertensive use in patients with comorbidities and polypharmacy increases the likelihood of encountering important drug-drug interactions. Dedicated efforts to better understand the relationship between pharmacokinetic drug interactions and pharmacogenomic information is important to advance efforts related to personalized medicine.