Captopril

Class ACE-inhibitor
Chemistry

L-proline derivative with sulfhydryl(-SH) group

Routes of administration

Oral

Absorption

75% oral bioavailability

Solubility

pKa 9.8

Distribution

2L/kg

Metabolism

60% hepatic metabolism

Elimination

40% renally excreted unchanged

Time course of action

Effects are maximal very shortly (15min) following oral administration, but the effect is short-lived (~ 6 hrs)

Target receptor

ACE enzyme

Mechanism of action

By interfering with a zinc moiety on the ACE enzyme, this drug nterrupts the conversion of Angiotensin-I into Angiotensin-II, thereby interrupting the effects of renin-angiotensin-aldosterone system activation, which are mainly mediated by Angiotensin II via the AT1 receptor.

Clinical effects

Vasodilation (without reflex tachycardia), increased natriuresis, increased sensitivity to diuretics, decreased glomerular filtration. Positive effects of vascular and myocardial remodelling in CCF. Also, dry irritating cough and a chance of random angioedema.

Literature reference

FDI PI booklet

CICM details of understanding Not specifically listed in the CICM syllabus
Mentioned around Deranged Physiology
Related SAQs