II. Indications
III. Contraindications
- Consider avoiding in Diabetes Mellitus (relative contraindication)
- May increase Proteinuria
- NOT contraindicated in combination with Beta Blockers
- Contrast with Non-Dihydropyridine Calcium Channel Blockers (Diltiazem, Verapamil) which slow AV nodal conduction
IV. Mechanism
- Nifedipine (Procardia) is prototype for class
- Dihydropyridine Calcium Channel Blockers
- Dihydropyridines are primarily active at vascular Smooth Muscle
- Contrast with Non-Dihydropyridines which are also active at cardiac Smooth Muscle
V. Medications: Oral
-
Amlodipine (Norvasc)
- Dosing
- Typical dose: 5 mg orally daily (may start at 2.5 mg daily in elderly)
- Maximum: 10 mg orally daily (little benefit over 5 mg, but increased edema)
- Advantages
- Preferred first line oral antihypertensive Calcium Channel Blocker
- Long acting and less reflex Tachycardia than other Dihydropyridines, with improved cardiovascular outcomes
- Does not exacerbate Left Ventricular Dysfunction
- Dosing
-
Nifedipine (Procardia)
- Consider in Hypertension control in pregnancy (long safety record)
- Felodipine (Plendil)
- Isradipine (Dynacirc)
- Nimodipine (Nymalize)
- Nisoldipine (Sular)
VI. Medications: Parenteral (Hypertensive Emergency)
- Background
- Counter Cerebral Vessel spasm (e.g. early Subarachnoid Hemorrhage, CVA)
- Clevidipine (Cleviprex)
- Nicardipine
VII. Adverse Effects
- See Calcium Channel Blocker
-
Peripheral Edema (esp. Amlodipine)
- Occurs more commonly in women
- Occurs more commonly on Norvasc doses >5 mg
- Adding ACE Inhibitor to regimen decreases edema
- Avoid Diuretics to reduce Dihydropyridine -induced edema
- Dihydropyridine-induced edema mechanism is vasodilation fluid leak into interstitium, NOT Sodium and water retention
VIII. Drug Interactions
-
Clarithromycin
- Increases Calcium Channel Blocker levels via CYP3A4 inhibition especially with Dihydropyridines and over age 65 years
- Provokes Hypotension and Bradycardia
- Risk of Acute Kidney Injury (often requiring hospitalization)
- References
- Increases Calcium Channel Blocker levels via CYP3A4 inhibition especially with Dihydropyridines and over age 65 years
IX. References
- (2022) Presc Lett 29(11): 64-5