AMLODIPINE

Amlodipine is a slow calcium channel blocker of dihydropyridine class

CLINICAL PHARMACOLOGY

Amlodipine selectively inhibits transmembrane influx of calcium ions, with greater selectivity for vascular smooth muscle than for myocardial tissue. This results in vasodilation and in reduction of blood pressure. The decrease in myocardial oxygen requirement along with coronary vasodilation accounts for beneficial effects in myocardial ischaemia. Amlodipine has gradual and sustained onset of action and blood pressure reduction is not associated with reflux tachycardia.

Amlodipine has no significant effect on sinus node function or cardiac conduction. Amlodipine is slowly and completely absorbed after oral administration with peak serum concentrations occurring after 6 to 12 hours. Oral bioavailability is 64% which is not influenced by food. Amlodipine has prolonged terminal elimination half-life of 35 to 50 hours and steady state concentrations are achieved after 7 to 8 days of administration. Amlodipine is extensively metabolised. Metabolites are mostly excreted in urine, with less than 10% of a dose as unchanged drug. Amlodipine is 97% protein bound.

INDICATIONS

  1. Hypertension
  2. Angina pectoris: Chronic stable angina, Vasospastic (Prinzmetal’s or variant) angina.

DOSAGE:

Initial dosage is 5mg once a day PO.

OVERDOSAGE:

In case of over dosage, the prominent feature is hypotension. Gastric lavage as well as symptomatic
and supportive measures to maintain blood pressure are indicated. Haemodialysis is not of value in removing circulating Amlodipine as it is highly protein bound.

CONTRAINDICATIONS

Amlodipine is contraindicated in patients with known hypersensitivity to dihydropyridine derivatives.

SIDE EFFECTS.

It is well tolerated.

  • Headache
  • Dizziness
  • Flushing
  • Palpitations
  • Peripheral oedema
  • Fatigue
  • Somnolence
  • Abdominal pain.
  • Muscle cramps
  • Dyspnoea
  • Dyspepsia
  • Pruritus
  • Rash

PRECAUTIONS

  1. In the elderly patients and those with liver disease, elimination of amlodipine is significantly reduced and half-life is prolonged. In such patients, Amlodipine should be given with caution with appropriate dosage reduction.
  2. All calcium channel blockers including Amlodipine should be used with caution in patients with heart failure.
  3. No dose adjustment is required in patients with renal impairment..
  4. Safety and efficacy of Amlodipine during pregnancy and lactation is not established.