Tramadol

Question 1

What class of drug is Tramadol

Answer 1

Cyclohexanol derivative

Question 2

Discuss the pharmaceutics

Answer 2

A racemic mixture of two enantiomers
Tablets can be immediate release or slow release in varying strengths from 60-400mcg
Solute for injection is 100mcg/2mLs

Question 3

What is the mechanism of action

Answer 3

Agonist properties at all opioid receptors, but mostly mu

Inhibits reuptake of noradrenaline and 5-HT, and stimulates release of 5-HT from presynaptic neurons

Question 4

What is the usual dose

Answer 4

3mg/kg regardless of route

Question 5

What is the oral bioavailability

Answer 5

70% with first dose, upto 90% with subsequent doses

Question 6

What is the onset and duration of immediate release preparations

Answer 6

Onset ~1hr, Duration ~9hrs

Question 7

What is the volume of distribution

Answer 7

3L/kg

Question 8

How much is protein bound

Answer 8

20%

Question 9

Outline the metabolism

Answer 9

Extensive hepatic via demethylation, glucuronidation and sulfation
Active metabolite O-desmethyl tramadol which exerts moderate stereoselective analgesic effects

Question 10

What is the elimination route and half-life

Answer 10

Renal excretion

Tramadol half life 6-8hrs, active metabolite 7-9hrs

Question 11

What are the major side effects

Answer 11

Use with caution in combination with SSRIs and MAOIs as may precipitate serotonin syndrome
Resp depression and constipation (less so than morphine)
High incidence of nausea and vomiting
Interacts with Warfarin
Possibility of drug related seizures - avoid in epilepsy