Ketamine - CBM Flashcards
1
Q
Ketamine: basic pharmacology
A
- NMDA antagonist
- all neurotransmitters in the brain (dopamine, adrenergic, serotonergic) influenced
- muscarinic , nicotinic antagonist
- reversal of opioid tolerance
- At high doses, it binds to opioid receptors (mu, kappa)
- At high doses, sodium channel blocker
- Oral metabolite norketamine more potent than parent compound.
- oral may be more potent than IV formulation
2
Q
What are the problems associated with ketamine?
Side effects
A
- Psychotomimetic symptoms
- dissociation, dysphoria, hallucinations
- Drowsiness
- Confusion
- pyoderma gangrenosum (SC injections)
- Hypertension, tachycardia
- Diplopia, nystagmus
3
Q
Ketamine Burst Protocol for refractory cancer pain
A
- Burst for maximum 5 days
- 100 mg / 24 hours
- If effective, continue for 3 days and stop
- if ineffective after 24 hours, increase to 300mg/24 hours
- If effective, continue x 3 days then stop
- If ineffective, increase to 500 mg / 24 hours, then stop.
- Stop regardless at 5 days
Journal of pain and symptom management vol 22 No 4 Oct 2001
Prospective multicentre unblinded open label audit trial
39 patients over 18 months (1998-1999)
Response rate 67%
4
Q
Ketamine contraindications
A
- has potential to raise ICP and IOP
- CI
- severe hypertension
- CVA
- epilepsy
- Use with caution in:
- brain mets
- raised ICP
- Raised IOP
5
Q
Ketamine : Continuous SC infusion
A
- 1-2.5 mg/kg per 24 hours
- increase by 50-100 mg / 24 hours
- Max dose 3.6 g / 24 hours
- 10-25 mg sc prn (0.5 mg/kg) for incidental pain or prior to procedures
6
Q
Ketamine : oral dosing
A
- May use from vial
- 10-25 mg tid-qid and prn
- Increase dose by 10 mg
- Up to 50 mg po qid
- Maximum 200 mg / day
- can use a smaller dose more frequently if psychomimetic SE
7
Q
Indications for Ketamine
A
- tertiary level drug when failure of two or more courses of strong opioids plus adjuvants
- Suspected OI hyperalgesia
