Drugs Mimicking SAN

Question 1

What are drugs mimicking San referred to as and what effects can they induce

Answer 1

Sympathomimetic or adrenergic drugs
1-drugs mimicking adrenergic receptors
2-indirectly inactivating adrenergic receptors
3-can act both directly and indirectly

Question 2

How can sympathomimetic drugs indirectly activate adrenergic receptors

Answer 2

Inc uptake of exogenous catecholamine

Inhibit re uptake of released catecholamine

Question 3

Adv of non catecholamine agents

Answer 3

Prolonged duration of action being non metabolized by COMPT or MAO enzymes

Question 4

Examples of the direct acting endogenous catecholamines and what they act on

Answer 4

Adrenaline: on all adrenergic receptors
Noradrenaline: strong affinity for a1 with less effect in B1 receptors
Dopamine: dose dependent activity on D1 B1 and a1 receptors

Question 5

What is adrenaline used for

Answer 5

▪️In anaphylactic shock: adrenaline give IM as its the physiological antagonist of histamine
Reverses hypotension and bronchoconstriction by acting in a1 and B2 receptors
Prevents further release of histamine through b2 activation

▪️cardiac arrest: intracardiac administration of adrenaline

Question 6

When is noradrenaline used

Answer 6

▪️In septic shock as it induces a strong vasopressor effect by activation of a1 receptors
▪️in hypovolemic shock

Question 7

When is dopamine used

Answer 7

In hypovolemic shock: maintains blood flow to kidney through vasodilator effect of D1 receptors
Elevates bp by activation of a1 and b1 receptors

Question 8

How can local administration of adrenaline be helpful

Answer 8

Local anesthesia to prolong action of anesthetic and prevent systemic absorption
Epistaxis as a local hemostatic agent

Question 9

What are the features of indirectly acting agents and what are they

Answer 9

Inc release of noradrenaline from synaptic vesicles and have longer duration of action and can be taken orally
Pseudoephedrine
Methamphetamine

Question 10

What does pseudoephedrine do

Answer 10

Used orally for its decongestant effect in case of common cold
OTC
Should be used cautiously in hypertension patients

Question 11

What does methamphetamine do

Answer 11

Highly addictive

Used in treatment of ADHD

Question 12

What do selective a receptor agonists generally do

Answer 12

Dissects vascular effects from cardiac actions and helps to avoid arrythmogenic potential of activating B1 receptors

Question 13

Elevates blood pressure in acute hypotensive states

Answer 13

Phenylephrine(IV)

Methoxamine (IV and IM)

Question 14

Used in chronic hypotension

Answer 14

Midodrine(oral)

Question 15

Used topically to relieve nasal and conjunctival congestion

Answer 15

Xylometazoline(nasal)

Oxymetazoline & phenylephrine(ocular and nasal)

Question 16

Decreases systemic blood pressure by decreasing sympathetic outflow in treatment of hypertension (in brain)

Answer 16

Clonidine

A methyl dopa

Question 17

Used in spinal cord to dec skeletal muscle spasticity by inhibiting release of excitatory neurotransmitters in treatment of spastic disorders

Answer 17

Tizanidine

Question 18

Used in eye to dec IOP by dec aqueous humor formation and dec drainage in treatment of glaucoma

Answer 18

Topical brimonidine

Question 19

Why do we use selective b receptor agonists

Answer 19

Clinically useful to achieve cardiac and bronchial effects without vasoconstrictor effect of a1 receptor activation

Question 20

What is the selective b1 agonist and what is it used for

Answer 20

Dobutamine used for positive inotropic effect as in cariogenic shock or acute heart failure

Question 21

What is the selective b2 agonist and what is it used for

Answer 21

Induces
Bronchodilation in case of treatment of bronchial asthma by using salbutamol and terbutaline (short acting)
Salmeterol (long acting)

Uterine relaxant to prevent premature labor by using ritrodine and tetrabutaline

Question 22

8 adverse reactions and toxicity

Answer 22

1-severe hypertension and headache and cerebral hemorrhage with non selective agents or with selective a1
2-cardiac arrhythmia of non selective and selective b1
3-reflex bradycardia with a1receptors
4-skeletal muscle tremors and tachycardia for selective b2 agonists
5-CNS excitation in form of fear and anxiety
6-high doses of amphetamines produces physchosis and convulsions
7-specific hypersensitivity reactions
8- topical nasal decongestants can:
-sting and burn and dry nostrils
- atrophy of cilia of nasal mucosa
-rhinitis medicamentosa