Source: Health Products Regulatory Authority (ZA) Revision Year: 2023 Publisher: Teva Pharmaceuticals (Pty) Ltd, Maxwell Office Park, Magwa Crescent West, Waterfall City, Midrand, Gauteng, 2090
A.2.9. Other analgesics
Opioids in combination with non-opioid analgesics, tramadol and paracetamol.
ATC code: N02AJ13
Tramadol is a centrally acting synthetic analgesic compound whose analgesic profile can be attributed to the binding of parent and O-demethylated (M1) metabolite to μ-opioid receptors as well as the weak inhibition of neuronal re-uptake of noradrenaline and serotonin. Paracetamol also has centrally acting analgesic effects.
Tramadol is well absorbed after oral administration, reaching peak activity in 2 to 3 hours. The mean absolute bioavailability of a single 100 mg oral dose is approximately 75%, increasing to approximately 90% with multiple dosing. Oral absorption of paracetamol following administration of CETVIO gives a peak plasma concentration of paracetamol within one hour and is not affected by co-administration with tramadol.
Tramadol has a high tissue affinity (Vd,β = 203 ± 40 L). It has a plasma protein binding of about 20%. Paracetamol appears to be widely distributed throughout most body tissues except fat. Its apparent volume of distribution is about 0,9 l/kg. A relative small portion (~20%) of paracetamol is bound to plasma proteins.
Tramadol and paracetamol are both extensively metabolised in the liver.
Approximately 30% of tramadol is excreted unchanged in the urine. Tramadol and its metabolites are eliminated primarily by the kidneys. The plasma elimination half-lives of tramadol and its M1 metabolite are approximately 6 and 7 hours respectively.
Paracetamol is eliminated from the body primarily by formation of glucuronide and sulphate conjugates in a dose-dependent manner. The half-life of paracetamol is about 2-3 hours in adults. Less than 9% of paracetamol is excreted unchanged in the urine.
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