Diltiazem

Question 1

What is diltiazem?

Answer 1

benzothiazepine derivative with vasodilating action

Question 2

What class of drugs does diltiazem belong to?

Answer 2

antihypertensive agents

Question 3

What are other drugs in the same class as diltiazem?

Answer 3

quinapril HCl
Enalapril maleate
Nifedipine
Captopril
Cilazapril

Question 4

What is diltiazem indicated for?

Answer 4

angina

hypertension

Question 5

What is the dose of diltiazem given for angina and hypertension?

Answer 5

Angina:
Oral 30mg 3-4x day. If necessarily increase to 240mg daily in divided doses. Max 360mg daily.

MR: oral 120-180mg OD increased at intervals of 7-14 days. Max 360mg daily.

Hypertension
Oral, MR: 180-240mg OD increased if necessary every 14 days. The usual maintenance is 240-360mg OD

Question 6

What is the mechanism of action of diltiazem?

Answer 6

Diltiazem inhibits the influx of extracellular Ca either by deforming the channel, inhibiting ion-control gatingin mechanisms or interfering with release of Ca from SR.
This causes inhibition of contractile processes of mycardial SMCs. The result is dilation of coronary and systemic arteries and improved O2 delivery to the myocardial tissue.

Question 7

What are the relevant PK or PD parameters of diltiazem?

Answer 7

PK: well absorbed from GIT but undergoes substantial FPM
70-80% protein bound
Metabolised and is an inhibitor of CYP3A4
Has a half life of 3-4.5 hours

Question 8

What are the precautions with diltiazem use?

Answer 8

heart filaure or significant impaired left ventricular function
bradycardia (avoid if severe)
First degree AV block
Prolonged PR-interval
Pregnancy class C: avoid
Compatible in breastfeeding
Reduce dose in hepatic and renal impairment

Question 9

What are the contraindications with diltiazem use?

Answer 9

severe bradycardia
left ventricular failure with pulmonary congestion
second or 3rd degree AV block unless a pacemaker is fitted
Sick sinus syndrome

acute porphyria

Question 10

What are the adverse effects with diltiazem?

Answer 10

bradycardia, SA block, AV block, palpitation, dizzienss, Hypotension, malaise, asthenia, headache, hot flushes, GI disturbance, oedema (ankles)

rash, photosensitivity are rare,

hepatitis, gynaecomastia, gum hyperplasia, extrapyramidal symptoms and depression have also been reported.

Question 11

What the interactions with diltiazem?

Answer 11

Increased risk of adverse effects when given with amiodarone, beta blockers, dronedarone,
plasma concentration of diltiazem increased with atazanavir

Diltiazem increases plasma concentrations of ciclosporin, colchicine, digoxin, phenytoin,

Question 12

What are the alarm bells associated with diltiazem use?

Answer 12

Monitor blood pressure….