26-27 Flashcards
(21 cards)
A 1 receptor location and action
Vascular smooth muscle
Vasoconstriction
A 2 receptor location and action
Presynaptic neurons
Action
Na release
Ach release
Insulin releas
Drugs blocking receptors Decrease or increase blood pressure?
Dec
Alpha have limited clinical applications because
Decrease blood pressure by the effect of alpha blockers induces a reflex tachycardia
Phenoxybenzamine is a
nonselective sympatholytic, linking covalently to both α1and α2 receptors
Phenoxybenzamine block is
irreversible
the only way the body can overcome
the Phenoxybenzamine block is to
synthesize new adrenoceptors
Phenoxybenzamine actions last about
24 hours.
Actions of phenoxybenzamine
Cardiovascular effects:
decreased blood pressure provokes a reflex
tachycardia
Therapeutic uses of Phenoxybenzamine
treatment of pheochromocytoma
treating Raynaud disease and frostbite
Adverse effects of phenoxybenzamine
- postural hypotension
- reflex tachycardia
Phentolamine Mechanism of action
competitive ( reversible) blocker of α1 and α2 receptors
Phentolamine Pharmacological actions
it produces postural hypotension
reflex cardiac stimulation and tachycardia
Phentolamine Therapeutic uses
management of pheochromocytoma.
Phentolamine can be administered by
intravenous or intramuscular route
Phentolamine half life is
short half-life, 19 min after intravenous administration
Prazosin, terazosin Mechanism of action
selective competitive blockers of the α1
receptor
Prazosin, terazosin Therapeutic uses
treatment of hypertension.
Prazosin, terazosin Adverse effects
dizziness, a lack of energy, headache,
drowsiness, and orthostatic hypotension,
Tachycardia
Tamsulosin mechanism
selective α1 antagonists
Tamsulosin uses
treatment of benign prostatic
hyperplasia
Blockade of the α1A receptors
decreases tone in the smooth
muscle of the bladder neck and
prostate and improves urine flow.
