Dihydropyridine calcium channel blockers

They block L-type (slow) calcium channels, mainly in arteriolar smooth muscle, so less calcium enters, the muscle relaxes and peripheral resistance falls. They act far more on vessels than on heart muscle, so at usual doses they barely depress the heart; instead the fall in pressure can set off a reflex rise in heart rate.

• AmlodipineIts very long half-life gives a slow, steady effect, unlike the 2-hour half-life of nifedipine.
• NifedipineImmediate-release forms swing blood levels widely, so slow-release forms are used for daily control; the NHS also lists it for Raynaud's.

• High blood pressure, as a first-line drug
• Angina, including vasospastic angina

• Ankle swelling (edema)Known for
• FlushingKnown for
• Fast heartbeat (reflex tachycardia), palpitationsKnown for
• Headache
• Dizziness
• Gum overgrowth (gingival hyperplasia)
• Worse angina or a heart attack on starting (rare)Serious
• Low blood pressure
• Tiredness
• Constipation

What the class has in common. Each drug's card has its own, and Known for marks what an exam expects you to know.

• Severe aortic stenosis: symptomatic low blood pressure is more likely.
• Severe coronary artery disease: angina or a heart attack can worsen on starting or raising the dose.
• They are not beta blockers and give no cover if a beta blocker is stopped suddenly; taper it instead.
• CYP3A4 inhibitors raise their levels and CYP3A4 inducers lower them.

Written for biofideX in plain words, after checking these references:

• Calcium Channel Blocker (NCI Thesaurus)
• Amlodipine besylate tablets: label (DailyMed)
• Nifedipine extended-release tablets: label (DailyMed)
• Guideline for the pharmacological treatment of hypertension in adults (WHO)
• Amlodipine (NHS)

For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.