Dihydropyridine CCBs
also: DHP · amlodipine class
Overview
Vascular-selective calcium-channel blockers. First-line for hypertension (esp. age ≥55 or Black African/Caribbean) and for stable angina.
Mechanism
Block L-type voltage-gated Ca²⁺ channels on vascular smooth muscle → ↓Ca²⁺ influx → arteriolar vasodilation → ↓systemic vascular resistance/afterload. Vascular-selective: negligible negative inotropy/chronotropy at therapeutic doses (unlike non-DHPs).
Indications
- Hypertension
- Stable angina
- Raynaud phenomenon
- Nifedipine: tocolysis (off-label)
The agents
t½ 35–50 h, once daily
Most-used; smooth 24 h cover; HTN + angina.
MR preparations only
Tocolysis, Raynaud. Avoid immediate-release for angina/HTN — reflex tachycardia.
OD
Strong CYP3A4 substrate — marked grapefruit interaction.
OD
Less ankle oedema than amlodipine (newer DHP).
Adverse effects
Precapillary arteriolar dilation — NOT fluid overload; does not respond to diuretics.
Worst with short-acting nifedipine.
Cautions & contraindications
Vasodilation drops coronary perfusion → syncope/collapse.
Reflex tachycardia ↑myocardial O₂ demand (short-acting).
Interactions
- CYP3A4 substrate — grapefruit juice raises levels
- Amlodipine + simvastatin: cap simvastatin at 20 mg/day (myopathy risk)
Monitoring & kinetics
Blood pressure,Peripheral oedema (clinical)
Oral; hepatic CYP3A4 metabolism. Safe in renal impairment (no dose adjustment).
Source: BNF — Calcium-channel blockers · NICE NG136 — Hypertension