1. Background information

a. Definition

• Drugs that block L-type calcium channels
• Two main classes (high-yield distinction):
  • Dihydropyridines (DHP): e.g. amlodipine, nifedipine → vascular selective
  • Non-dihydropyridines (non-DHP): e.g. verapamil, diltiazem → cardiac + vascular effects

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b. Mechanism of action

• Block Ca²⁺ entry into smooth muscle and cardiac cells

DHP (e.g. amlodipine):

• Peripheral vasodilation → ↓ BP → ↓ afterload

Non-DHP (verapamil/diltiazem):

• ↓ AV node conduction (rate control)
• ↓ contractility (negative inotrope)

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c. Indications (NICE aligned)

Hypertension

• First-line in ≥55 years or Black African/Caribbean origin

Angina

• First-line (stable angina)

Atrial fibrillation

• Rate control (verapamil/diltiazem)

Other:

• Raynaud’s phenomenon (DHP)

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2. Assessment

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a. Contra-indications

DHP (e.g. amlodipine):

• Severe hypotension
• Cardiogenic shock

Non-DHP (HIGH-YIELD):

• Heart failure (HFrEF)
• Bradycardia
• 2nd/3rd degree AV block (no pacemaker)

👉 Avoid combining verapamil + β-blocker (risk of heart block)

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b. Drug interactions

Non-DHP important interactions:

• β-blockers → bradycardia / heart block
• Digoxin → ↑ digoxin levels
• CYP3A4 inhibitors (macrolides, azoles)

DHP:

• Grapefruit juice → ↑ levels

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c. Toxicity

DHP toxicity:

• Marked vasodilation → hypotension, reflex tachycardia

Non-DHP toxicity:

• Bradycardia
• AV block
• Heart failure

Severe overdose (exam):

• Hypotension + bradycardia + shock

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d. ECG features

Non-DHP effects:

• PR prolongation
• Bradycardia
• AV block

DHP:

• Usually no direct ECG changes
• Reflex tachycardia possible

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e. Monitoring (WITH TIMELINES – HIGH YIELD)

Baseline (before starting)

• BP
• Pulse
• ECG (if using verapamil/diltiazem)
• LFTs (if clinically indicated)

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After initiation / dose change

• BP check:
  • After 2–4 weeks
• Pulse check (non-DHP):
  • After 2–4 weeks

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Ongoing monitoring

• BP:
  • Every 3–6 months once stable
• Pulse (non-DHP):
  • Periodically (especially if symptomatic)

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Additional monitoring (non-DHP)

• ECG if:
  • Bradycardia
  • Dizziness/syncope
  • Conduction concerns

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Clinical monitoring

• Ankle swelling (DHP)
• Constipation (verapamil)
• Symptoms of heart failure

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3. Management (NICE CKS aligned)

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a. Side effects AND what to do

Side effect	Cause	Action
Ankle oedema (DHP)	Vasodilation	Reduce dose or switch (common exam Q)
Headache/flushing	Vasodilation	Usually self-limiting
Bradycardia (non-DHP)	AV node suppression	Stop drug, check ECG
Constipation (verapamil)	Reduced GI motility	Manage symptomatically
Hypotension	Excess vasodilation	Reduce dose / stop

👉 Key AKT point:

• Ankle oedema = class effect (not fluid overload)

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b. Use in Primary Care

• Commonly initiated and managed in GP

Hypertension:

• First-line in ≥55 or Black patients (amlodipine)

Angina:

• First-line (DHP or rate-limiting CCB)

AF:

• Verapamil/diltiazem for rate control (if β-blocker unsuitable)

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c. Use in Secondary Care

• Acute arrhythmias (e.g. AF rate control IV)
• Specialist management:
  • Complex hypertension
  • Resistant angina
  • Arrhythmia management

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🔑 AKT ULTRA-HIGH YIELD SUMMARY

• 2 types:
  • DHP → vessels (amlodipine)
  • Non-DHP → heart (verapamil/diltiazem)
• DHP = oedema, flushing
• Non-DHP = bradycardia, heart block
• Avoid:
  • Verapamil + β-blocker
  • Non-DHP in heart failure
• Monitoring:
  • BP at 2–4 weeks, then 3–6 monthly
  • Pulse monitoring for non-DHP
• ECG: PR prolongation (non-DHP)