Pharmacology 1

Question 1

Competitive neuromuscular blockade maybe prolonged by?

Answer 1

Hypothermia
Hypokalaemia
Hypocalcaemia
Metabolic acidosis

Meds: Lithium, Neomycin, calcium channel blockers, aminoglycosides
- drugs that reduce pre-synaptic Ca entry

Question 2

Ketamine:

• how many chiral centres?
• what type of mixture?
• cardiac effect?
• effect on cerebral blood flow?
• receptor activity?
• bronchodilator or constrictor?

Answer 2

• one chiral centre
• racemic mixture of two enantionmers, S (+)ketamine and R(-)-ketamine
• positive ionotropic, increase HR/ BP/ CO
• increases CBF, ICP
• non-competitive inhibitor of ions associated with NMDA receptor (blocks)
• bronchodilator

Question 3

what can induce enzymes that are responsible for the metabolism of halothane?

Answer 3

Chronic barbiturate use, alcohol or cigarettes

Question 4

What determines the alveolar partial pressure required to maintain anaesthesia and MAC?

Answer 4

Related to lipid solubility, expressed by oil gas coefficient.

Question 5

What does blood gas coefficient determine?

Answer 5

The rate of onset and offset of effect of inhalational anaesthetic agents.

Question 6

Drugs hydrolysed by esterases?

Answer 6

Aspirin
Diamorphine
Tetracaine

These are all esters

Question 7

Does the ionised or unionised fraction of a drug bind to plasma protein?

Answer 7

The un-ionised because it will need to either acquire (weak base) or give up (weak acid) a proton to bind.

Question 8

Which drugs act by altering the cell membrane sodium permeability?

Answer 8

• Local anaesthetics

- bumetanide, triamterene (inhibit Na transport in renal tubular membranes, DCT)

Question 9

What mechanism does GTN act by?

Answer 9

It is converted to nitric oxide
Activates cytoplasmic guanylate cyclase in vascular smooth muscle
- vasodilation

Question 10

What is the function of adenylyl cyclase?

Answer 10

• membrane bound enzyme
• catalyses formation of cAMP from ATP
• indirectly activated by catecholamines binding to beta-adrenoreceptors.

Question 11

How does aminophylline affect cAMP?

Answer 11

It is a Phosphodiesterase inhibitor,

phosphodiesterase would break down cAMP to inactive 5’-AMP. Therefore it increases cAMP.

Question 12

Salbutamol effect on adenylyl cyclase?

Answer 12

Is a b2 agonist results in adenylayte cyclase activation.