Study Set Content:
a 1-receptor antagonists may have additional effects on cells in the prostate that help improve
symptoms.
are all efficacious in patients with BPH. Useful in patients who also have hypertension.
Prazosin, doxazosin, and terazosin
is also efficacious in BPH and has relatively minor effects on blood pressure at a low dose. Preferred in patients who have experienced
Tamsulosi
A combination of____ with the nonspecific smooth muscle relaxant____, when injected directly into the penis, may cause erections in men with sexual dysfunction.
phentolamine, papaverine
Long-term administration may result in fibrotic reactions. Systemic absorption may lead to
orthostatic hypotension;
Priapism-direct treatment with an a-adrenoceptor agonist such as
phenylephrine.
Alternative therapies for erectile dysfunction include prostaglandins, sildenafil and other cGMP phosphodiesterase inhibitors and
apomorphine.
have relatively little clinical usefulness.
Alpha 2 antagonists
They have limited benefit in male
erectile dysfunction.
There has been experimental interest in the development of highly selective antagonists for treatment of ()(a 2 receptors inhibit insulin secretion), and for treatment of
type 2 diabetes psychiatric depression.
occupy B receptors and competitively reduce receptor occupancy by catecholamines and other B agonists
Beta-blocking drugs
Most B-blocking drugs in clinical use are
pure antagonists;
However, some are partial agonists; that is, they cause partial activation of the receptor, less than that caused by the full agonists
epinephrine and isoproterenol.
inhibit the activation of 3 receptors in the presence of high catecholamine concentrations but moderately activate the receptors in the absence of endogenous agonists
Partial agonists
Some B blockers (eg, betaxolol, metoprolol) are____– drugs that reduce constitutive activity of 5 receptors-in some tissues
inverse agonists
The B-receptor-blocking drugs differ in their relative affinities for
1 and B 2 receptors
Since none of the clinically available ß-receptor antagonists are absolutely specific for 3 1 receptors, the selectivity is doserelated; it tends to diminish at
higher drug concentrations
ADRENERGIC ANTAGONISTS
Examples of selective 1 blockers
• Atenolol (Tenormin)
• Esmolol (Brevibloc)
• Acebutolol (Sectral)
• Metoprolol (Lopressor
In general, ß blockers starting with____ are cardioselective.
A or M
At high doses, these drug will block (blank) may have important clinical
implications.
B, receptors selectivity
