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Author: Admin | 2025-04-28
Contraction, which helps treat hypertension, reduces oxygen demands, and provides cardiac rate control which can be important for patients with cardiac dysrhythmias such as tachycardia. While both verapamil and diltiazem exhibit these effects, verapamil has been shown to lower heart rate and contractility more than diltiazem. While both classes are substrates of CYP3A4, non-DHPs are also inhibitors of 3A4 and, therefore, cause more drug-drug interactions. Verapamil has also been shown to modestly inhibit CYP2C9, 2C19, and 1A2. Due to this, as well as the increased risk of bradycardia and atrioventricular block, verapamil and higher doses of diltiazem often are not recommended to be taken with beta-blockers. Non-DHP’s side effect profile is also slightly different than DHPs, due to the difference in targets mentioned previously. Non-DHP CCBs carry a risk of lower cardiac output and bradycardia. Verapamil has also been shown to have a higher incidence of constipation at higher doses. In addition to the general CCB contraindications, non-DHPs are also contraindicated in patients with HFrEF (EF (definitely a good board exam nugget!).In comparison to non-DHPs, DHPs have little effect on the myocardium and target peripheral vasodilators. Due to this, side effects caused by DHPs include lightheadedness, flushing, headaches, peripheral edema, and (for short-acting formulations) reflex tachycardia. A brief table can be found below depicting the main differences between the DHPs and Non-DHPs. DHP vs Non-DHP Calcium Channel Blocker ComparisonDrug ClassDHPNon-DHPExamplesAmlodipine, nicardipine, nifedipine, felodipineVerapamil, diltiazemFDA Approved UsesHypertension, anginaHypertension, angina, atrial dysrhythmias, tachycardiaTargeted AreaSmooth muscleHeart Muscles and Smooth MuscleVasodilationMore vasodilationLess vasodilationSystemic Vascular Resistance (SVR)Decreased SVRLess SVR decreaseContractilityNo effectDecreased contractilitySinus Node RateNo effectDecreased rateAV Node RateNo effectDecreased rateClass Specific AEsDizziness, flushing, headaches, peripheral edema, palpitationsConstipation, bradycardia, lowered cardiac outputDihydropyridines Versus Non-Dihydropyridine Calcium Channel BlockersAs we can see in our calcium channel blocker comparison, these medications may have the same overall grouping of CCBs
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