Medwiki

Diltiazem

Trade name(s): Cardiazem Drug Class:Calcium-Channel Blocker

Theraputic use: THis is used as a depression of Sa and AV node conduction as well as reduced inotrophy and chronotropy of cardiac contraction.

it is used as an antiarrhythmic and an antihypertensive

Pharmacological action:

Pharmacokinetics:

  • Administration Well absorbed from the GI tract extensive first pass effect given oral delivery 40% of total.

  • Distribution 70-80% binding to plasma proteins.

  • Metabolism Extensive metabolism in which 2-4% of the unchanged drug appears in urine.

Plasma elimination half life is 3-4.5 hours. Departure of linearity with increased dose in conventional and SR tablets

Minimum theraputic concentration is around 50-200 ng/mL

  • Excretion mostly excreted in urine

Indications:

  • Angina, hypertension, atrial fibrillation, atrial flutter, paroxysmal supra ventricular tachycardia

Contraindications: severe bradycardia, hypotension, left ventricular failure with pulmonary congestion, acute MI with pulmonary congesiton, heart failure with reduced ejection fraction 2nd or 3rd degree AV block or sick sinus stsrome, concomitant dantrolene, ivabradine, pregnancy, breastfeeding

Precautions: Significantly impaired left ventricular function brady cardia, first degree AV block prolonged PR-interval, patients at risk of intestinal obstruction, elderlym diabetes mellitus, bronchial hypersensetitivy, avoid abrupt withdrawl in patients with angina

Adverse reactions:

mostly form over cooking dose

  • brady cardia
  • SA block
  • AV block
  • palpitation, dizziness, hypetension, malaise, asrthenia, headache, hot flushes, GU disturbances, oedema

Interactions:

dantrolene - hyperkalaemia vabradine and a number od -tinib drugs

There are lots and lots of interactions

Dosing/Current guidelines:

Angina Oral tablet immediate release Adult 30 mg 3–4 times daily (elderly initially twice daily) increased if necessary to 240 mg daily in divided doses max 360 mg daily

Oral, modified release Adult 120–180 mg once daily, increased if necessary at intervals of 7–14 days; maximum 360 mg daily

Hypertension

Oral, modified release Adult 180–240 mg once daily, increased if necessary every 14 days; usual maintenance 240–360 mg once daily

Atrial fibrillation or atrial flutter (ventricular rate control)

Oral, immediate release Adult 60 mg 3 times daily, increased if necessary to maximum 360 mg daily in 3 or 4 divided doses

Oral, modified release Adult 120–180 mg daily, increase if necessary to maximum 360 mg daily

Slow intravenous injection Adult 250 micrograms/kg (usual maximum 20 mg) over 2 minutes; if inadequate response after 15 minutes a second bolus of 350 micrograms/kg (usual maximum 25 mg) may be given over 2 minutes; subsequent bolus doses should be individualised, or a continuous intravenous infusion started

Continuous intravenous infusion Adult following intravenous bolus dose, initially 10 mg/hour (some patients may respond to 5 mg/hour); increase if necessary in steps of 5 mg/hour to maximum 15 mg/hour; continue for maximum 24 hours

Paroxysmal supraventricular tachycardia (cardioversion)

Intravenous injection Adult 250 micrograms/kg (usual maximum 20 mg) over 2 minutes; if inadequate response after 15 minutes a second bolus 350 micrograms/kg (usual maximum 25 mg) may be given over 2 minutes; subsequent bolus doses should be individualised, or a continuous intravenous infusion started

Continuous intravenous infusion Adult following intravenous bolus dose, initially 10 mg/hour (some patients may respond to 5 mg/hour); increase if necessary in steps of 5 mg/hour to maximum 15 mg/hour; continue for maximum 24 hours

Monitoring: Overdose: oral ld50 in mice and rats are 415-740 and 560 and 810 respectively the intraventous dose were 60 and 38 respectively. OD may result in bradycardia, high degree AV block, cardiac fialur, and hypotension etc use supportive treatment or drug treatment

Treatment of OD: atropine fluid and vasopressors have been used inotropic agents also used

in general ventilator support, gastric lavage activated charcoal, intravenous calcium (unsure if helps or not)

Bradycardia Administer atropine (0.60 to 1.0mg). If there is no response to vagal blockade administer isoprenaline cautiously.

High Degree AV Block Treat as for bradycardia above. Fixed high-degree AV block should be treated with cardiac pacing.

Cardiac failure Administer inotropic agents (isoprenaline, dopamine, or dobutamine) and diuretics.

Hypotension Vasopressors (e.g. dopamine or noradrenaline acid tartrate). Actual treatment and dosage should depend on the severity of the clinical situation and the judgement and experience of the treating physician. Symptoms and signs of overdose may be delayed due to the controlled release properties of the product, so patients should be kept under observation for at least 24 hours.

Pregnancy

Subsidised? modified release capsule is fully subsidised (diltiazem dc (clinect), cardiazem CD)

What to tell patients:

Comments/Observations/notes:

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