IASM sympathetic drugs

Question 1

alpha 1 receptor agonist

Answer 1

phenylephrine:
vasoconstriction (increased bp)
smooth muscle contraction except GI
-> decongestants

Question 2

alpha 2 agonist

Answer 2

Clonidine:
reduce CO, reduce vasoconstriction and bp
also act on the CNS to reduce the sympathetic output
-> migraine and hypertension

Question 3

Non-selective beta agonist

Answer 3

• isoprenaline/isoproterenol
• increase CO, vasodilation, smooth muscle relaxation
• > used for asthma but now obsolete due to effect on heart

Question 4

beta 1 agonist

Answer 4

• dobutamine
• increase CO (contractility and heart rate) and bp
• used in hypotension and heart failure

Question 5

beta 2 agonist

Answer 5

• salbutamol and terbutaline
• smooth muscle relaxation and vasodilation
• used in asthma as bronchodilator

Question 6

beta 3 agonist

Answer 6

• mirabegron
• treat overactive bladder by inhibiting bladder contraction
• promote lipolysis and thus may help in obesity

Question 7

indirect sympathomimetic amines- examples

Answer 7

tyramines

ephedrine/pseudoephedrine

Question 8

tyramine

Answer 8

• rich in fermented cheese
• increase NE output by NET (NE transporter)
• readily metabolised by MAO, but if taken with anti-depressant which inhibits MAO -> dangerous rise in bp
  0 no clinical use

Question 9

ephedrine

Answer 9

• increase NE by NET
• directly stimulates the alpha and beta receptor
• inhibits the MAO
• used as decongestants

Question 10

non-selective alpha blockers

Answer 10

• phentolamine and phenoxybenzamine
• > vasodilation and reflex tachycardia
• > may need beta blockers to control the heart rate
• smooth muscle relaxation
• phaeochromocytoma (excessively catecholamines)

Question 11

alpha 1 blockers

Answer 11

• tamsulosin and prazosin
• vasodialtion and reflex tachycardia
• smooth muscle relaxation
• hypertension and BPH (hypertrophy)

Question 12

alpha 2 blockers

Answer 12

• yohimbine
• increase NE release and thus CO, vasoconstriction and bp
• smooth muscle relaxation
• no clinical use

Question 13

beta blocker (non-selective)

Answer 13

• propranolol and timolol
• reduce CO and cause vasoconstriction, smooth muscle contraction
• angina, hypertension, arrhythmia, anxiety (beta 1 in CNS) and tremor (beta 2 in Skeletal)
• timolol used in glaucoma to reduce secretion of aqueous humour from ciliary epithelium

Question 14

beta1 blocker

Answer 14

• metoprolol
• reduce CO and bp
• hypertension, angina and arrhythmia

Question 15

beta 2 blockers

Answer 15

• butaxamine
• vasocontriction and smooth muscle contraction
  no use

Question 16

mixed alpha beta blockers

Answer 16

• carvedilol and labetalol
  affinity for beta greater than alpha1
• reduce in CO but vasodilation, smooth muscle contraction
• hypertension

Question 17

drugs affecting NE synthesis

Answer 17

• methyldopa
• converted into false neurotransmitter (alpha methylnoradrenaline)
• not deaminated by MAO, thus displace the NE
• weaker stimulation of alpha 1 -> reduce vasoconstriction
• stronger stimulation of alpha 2 -> reduce NE release
• central effect on CNS
• hypertension treatment