Tramadol at a glance

Tramadol was launched in Germany for the first time in 1977. Currently it is used as an analgesic worldwide. It is synthetic opioid of benzemoid class (due to benzene ring in its structure). In the body it is metabolised to O-dysmethyltramadol which is more potent than the parent drug. It is metabolised in the liver and excreted in urine (95 per cent), so a change in dosage is recommended in those with liver and renal impairment.
Tramadol is primarily used to treat mild to moderate pain, both in acute and chronic conditions. After oral use, onset of effect happens in one hour and peaks in 2-4 hours. It has 1/10 the potency of morphine. Its use in children is usually advised against, although it may be done under specialist supervision. In elderly patients, the risk of respiratory depression, falls, sedation and cognitive impairment is increased. The pharmacology, side effects, contraindications and interactions are summarised as.

Pharmacology of “TRAMADOL”
T Tramadol is a synthetic opiate
T1/2 is 6-7.5 hours
R Reuptake of serotonin+noradrenaline is mechanism of action (80 per cent)
A Antagonist at NMDA?
M Mu agonist (20 per cent)
Molecular formula C16 H25 NO2
Molecular weight is 263
A Attached to protein (binding) 20 per cent
Availability (bio) PO 75 per cent and injected 100 per cent
D Distribution volume PO is 306 L and IV is 203L
O O-dysmethyltramadol (metabolite) has 200times more affinity for Mu receptor
L Liver metabolism via cytochrome P450 isoenzyme

The lists of drugs interacting with “TRAMADOL”
T TCAs
R Recreational drugs eg. Amphetamine
A Antibiotics eg linezolid and isoniazid
M MAOIs
A Anxiolytics e.g. SSRIs and buspiron
D Dye e.g. methylene blue
O Oxycodone and pethidine
L Lithium
Side effects of tramadol, remember “ 7Ss”
S Seizures
S Serotonin syndrome
S Sickness
S Sleep disorder
S Sinus tachycardia
S Sharp episodes of hypotension
S Skin: hives

For contraindications, remember “6Hs”
H Head injury
H Hydrocephalous
H History of epilepsy and serotonin syndrome
H Hypersensitivity
H Hypnotic overdose
H Heavy alcohol intake
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Authors:

Sher Mohammad¹
Naveena Sukumaran²
Piya Dhar³
Kishori Bawdane⁴
Ahmad Daoud⁵
Sibghatullah M.Khan⁶

1. Consultant Anaesthetist
2. SAS
3. SAS
4. MTI
5. Locum SpR
   Anaesthetics Department, Royal Hallamshire Hospital, Glossop Road, Sheffield
6. Specialist anaesthetist, Hamad Medical Corporation, Doha Qatar

Staff Writer