Adrenergic Agonist Drugs

Question 1

Alpha adrenergic receptors

Answer 1

1. Alpha 1- vasoconstriction, increases anal spinchter tone, increases urinary spinchter tone, mydriasis.
2. Presynaptic alpha 2 - negative feedback on Na secretion
3. Postsynaptic alpha 2- vasoconstriction, venoconstriction.
4. Alpha 2 receptors on secretions - decrease insulin secretion, reduces aqueous humour secretion, decreases Na release.

Question 2

Beta adrenergic receptors

Answer 2

1. Activation of beta 1 causes- cardiac stimulation, renin release.
2. Activation of beta 2 causes (stimulatory)- glycolysis stimulation, skeletal muscle contraction, increases aqueous humour secretion, uptake of potassium into cells.
3. Activation of beta 2 (inhibitory) - relaxation of bronchi, pregnant uterus, vascular, bladder muscles, GI muscles.
4. activation of beta 3 - lipolysis.

Question 3

Classification based on therapeutic uses

Answer 3

1. To raise BP in shock- dopamine, noradrenaline, phenylephrine.
2. Bronchodilator- Salbutamol, terbutaline, salmeterol.
3. Cardiac stimulant - Adrenaline, isoprenaline, dobutamine.
4. CNS stimulant - amphetamine, methampetamine.
5. Local vasoconstriction- Adrenaline
6. Nasal decongestant- phenylephrine, pseudoephedrine
7. Anorexiant - dextroamphetamine, mazindol
8. Uterine relaxant - terbutaline, salbutamol
9. Mydriatic - ephedrine, phenylephrine

Question 4

Pharmacological actions

Of adrenaline-a1,2, b1,2,3

Answer 4

1. CVS - a. Heart : positive (chronotrophic, inotrophic, dronotrophic) increases (CO, HR, automacity, excitability, oxygen demand, arrthymias)
   b. Vasoconstriction (skin, mucous membranes, renal, mesentric, pulmonary, splanchnic)
   Vasodilation (skeletal muscle vessels and coronary vessels).
   On i.v there is initial rise in BP(a1,b1), and followed by fall (b2). There is vasomotor reversal on administration of adrenaline after administration of alpha blocker.
2. Relaxes b2 brochial smooth muscles, inhibits release of inflammatory mediators. Reduces secretion and relives mucosal congestion a1.
3. Reduces intestinal tone and peristaltic movements. a2&b2
4. Relaxes detrusor, contracts sphincter.
5. Stimulant of hepatic glycogenolysis.
   Reduces insulin secretion
   Decreases uptake of glucose in peripheral tissues. Increases lactic acid levels
6. Postpones fatigue
   Reduces plasma potassium levels

Question 5

Pharmacokinetics of adrenaline

Answer 5

1. Given subcutaneously(low doses) and intramuscularly(anaphylactic shock) intravenously (cardiac arrest)
2. Metabolized by COMT , MAO.
3. Excreted in urine.

Question 6

Adverse effects of adrenaline

Answer 6

1. Tachycardia, palpitation, headache, restlessness, tremors, hypertension.
2. Cerebral haemorrhage, cardiac arrthymias,
3. In high doses, may cause acute pulmonary oedema.

Contraindicated in cardiac diseases.

May cause hypertensive crisis and cerebral haemorrhages in patients on beta blockers.

Question 7

Therapeutic uses

ABCDE

Answer 7

1. Anaphylactic shock: 0.3 ml- 0.5ml of 1:1000 solution.
2. Bronchial asthma : 0.3-0.5ml pf 1mg/ml subcutaneously.
3. Cardiac resuscitation: 1:10000 intravenously.
4. Prolonging duration of local anaesthesia: adrenaline with lignocaine.
5. Control of epistaxis and capillary oozing
6. Glaucoma : as prodrug.

Question 8

Selective b2 agonists
Therapeutic uses
Adverse effects

Answer 8

TU: 1. Bronchial asthama: salbutamol

2. Premature labour: salbutamol, terbutaline
3. Hyperkalaemia

AE: Tremors, tachycardia, hyperglycaemia, hypokalaemia.

Question 9

Amphetamine

Uses

Answer 9

1. Narcolepsy
2. Anorexiant
3. ADHD

Question 10

Ephedrine

Uses

Answer 10

1. Drug of choice to treat hypotension due to spinal anaesthesia.

Question 11

Dopamine
Pharmacological actions
Therapeutic uses

Answer 11

1.