Review of Pharmacology - 9E (2015)

Autonomic Nervous System
103. Ans. (c) Phenylephrine (Ref: Harrison /18/e p377-378)
Alpha blockers are used in erectile dysfunction not alpha agonists (phenyephrine).
Drugs useful in the management of erectile dysfunction (ED)
• Phosphodiesterase inhibitors
––
Sildenafil
––
Vardenafil
––
Tadalafil
––
Udenafil
• PGE 1
analog – Alprostadil
• Aviptadil
104. Ans. (a) Dobutamine decreases peripheral resistance (Ref: Harrison 18/e p1913)
Dobutamine acts by activating b 1
receptors and may decrease the peripheral resistance by its minor effect on b 2
receptors.
It has no effect on dopamine D 1
or D 2
receptors.
• Dobutamine is a direct-acting inotropic agent whose primary activity results from stimulation of the b receptors of
the heart while producing comparatively mild chronotropic, hypertensive, arrhythmogenic, and vasodilative effects.
It does not cause the release of endogenous norepinephrine, as does dopamine. In animal studies, dobutamine produces
less increase in heart rate and less decrease in peripheral vascular resistance for a given inotropic effect than
does isoproterenol.
• Systemic vascular resistance is usually decreased with administration of dobutamine. Occasionally, minimum vasoconstriction
has been observed. Similarly coronary blood flow may be increased with dobutamine.
105. Ans. (b) 1 : 1000 for inhalational route (Ref: Drug Facts and Comparisons, 2010/837)
For inhalational route, adrenaline is used in a concentration of 1:100 for treatment of bronchial asthma by nebulizer.
106. Ans. (b) As a vasodilator in treating coronary artery stenosis during angio procedures (Ref: CMDT-2010/1434-1435)
Tolazoline and phentolamine are alpha receptor blockers, therefore produce vasodilation.
107. Ans. (b) Salmeterol (Ref: KDT 6/e p216, 217, 218 & 5/e p200)
Salmeterol is a long acting β 2
agonist whereas albuterol (salbutamol), pirbuterol and orciprenaline are short acting agents.
108. Ans. (b) Dobutamine (Ref: Harrison 17/e p1399-1400)
• Pharmacological stress testing is done in individuals who are not able to exercise.
• It is done by infusion of dobutamine to increase myocardial oxygen demand.
109. Ans. (a) Ephedrine (Ref: Current Diagnosis And Treatment-obstetrics And Gynecology, 2008)
Vasopressors act by stimulating alpha adrenergic receptors. This vasoconstriction can lead to fetal hypoxia by reducing
uteroplacental perfusion. Vasopressors acting predominantly by alpha receptors can also increase uterine tone and further
aggaravate the fetal hypoxia. Phenylephrine, methoxamine and mephentermine are all alpha agonists and can cause this
side effect so not preferred in pregnant female.
Ephedrine on the other hand possess beta adrenergic activity also and result in less vasospasm (due to beta 2 mediated
vasodilation) and is considered as the vasopressor of choice in pregnant females especially for the treatment of hypotensive
complication of regional anaesthesia.
tahir99 - UnitedVRG
110. Ans. (a) Stimulation of lipolysis (Ref: Katzung 10/e p86; KDT 6/e p119)
Lipolysis is mediated by b 3
receptors whereas other actions are done by stimulation of b 2
receptors.
111. Ans. (a) Hypertensive emergencies (Ref: Katzung 10/e p133, 174)
• Fenoldopam is a D 1
agonist useful for i.v. treatment of hypertensive emergencies.
112. Ans. (b) Conversion of tyrosine to dopa (Ref: Katzung 10/e p78; KDT 6/e p116-117)
• Rate limiting enzyme in norepinephrine synthesis is tyrosine hydroxylase that catalyses the conversion of tyrosine to
dopa. In ACh synthesis, rate limiting step is uptake of choline by the neurons.
113. Ans. (d) Hypokalemia (Ref: KDT 6/e p124 and Principles of pharmacology by HL Sharma and KK Sharma 2007/168)
• β 2
agonists cause a brief spell of hyperkalemia followed by hypokalemia.
• These do not cause hypoglycemia. However, β 2
blockers delays the recovery from hypoglycemia.
114. Ans. (b) Hypoglycemia (Ref: KDT 6/e p124)
Autonomic General Pharmacology
Nervous System
• β 2
agonists are the inhaled bronchodilators used for the management of bronchial asthma.
• Tremor is the dose related adverse effect of these drugs.
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