Which of the following drug causes postural hypotension commonly?
Alpha 1A receptors are present on prostatic urethra whereas alpha 1B/1D are present on blood vessels. Drugs blocking both of these (like prazosin, terazosin, doxazosin and alfuzosin) are useful in BHP with hypeension but cause postural hypotension (First dose effect) as an adverse effect due to VENODILATION -hence causing pooling of blood in extremities -decreased venous return causing postaural hypotension. Selective alpha 1A blockers (tamsulosin and silodosin) treat symptoms of BHP without causing postural hypotension. Other drugs causing postural hypotension - ACE inhibitors- Enalapril Sodium nitroprusside.
ACE inhibitor
Beta blocker
Alpha blocker
Angiotensin receptor blockers.
FMGE 2019