CNS

Question 1

Tetrahydrocannabinol (THC)

Answer 1

• targets receptors in the endocannacinoid system impacting on pain modulation, memory and appetite
• targets the CB1 receptor, found mostly in brain and CNS
• cannabinoid receptors are found on the presynaptic neuron
• CB1 decreases intestinal hypersecretion and hypermotility, and decreases epithelial wounds and visceral pain

Question 2

Cannabidiol (CBD)

Answer 2

• doesn’t fit the CB1 or CB2 receptors but has powerful indirect effects
• still being studied

Question 3

Cannabinol (CBN)

Answer 3

• targets CB2 receptors mainly in peripheral organs (esp. immune)
• CB2 decreases inflammatory mediators and visceral pain

Question 4

What is the endogenous cannabinoid neurotransmitter?

Answer 4

Anandamide

Question 5

Flumazenil

Answer 5

• BZD antagonist used as an antidote for OD or to reverse anaesthesia
• Negative allosteric modulator - binds to GABA channel and slows influx of Cl- into neuron
• administered via IV
• ADRs: anxiety, confusion and nausea

Question 6

Phenobarbital

Answer 6

• non-selective CNS depressant used as an anticonvulsant in children
• positive allosteric modulator - enhances GABA transmission by increasing GABA pore opening duration
• inhibits glutamate transmission
• ADRs: dangerous in OD (resp depression), tolerance, dependence, drug-drug interactions, CYP inducer, decreases plasma concentration of steroids, OCs and warfarin. - Given IV for status epileptics.
• Broad spectrum AED.

Question 7

Dextromethorphan

Answer 7

• antitussive (cough suppressant) with sedative properties

- NMDA receptor antagonist

Question 8

Memantine

Answer 8

• NMDA receptor antagonist.
• Inhibits over stimulation of glutamate receptors.
• Requires dose titration over a month to minimize ADRs of agitation, hallucination and headache. Not suitable for those with renal impairment.

Question 9

Ketamine

Answer 9

• anaesthetic used for starting and maintaining anaesthesia

- NMDA receptor blocker that antagonists the action of the NMDA receptor

Question 10

Entacapone

Answer 10

• COMT inhibitor.
• Inhibits degradation of dopamine.
• Increases the duration of effect of levodopa dose. Can increase peak levels of levodopa, and should be taken with carbidopa/levodopa.
• Can reduce the required dosage of levodopa/carbidopa.