Core pharmacology

Class Group

Non-Opiate Analgesic

Legacy Cicm Level

Level 3

Introduction

non selective cycloxygenase inhibitor

Indications Uses

Analgesia
Antipyretic
Antiinflammatory

Presentation

200mg tablets, some formulations in combination with codiene

Mechanism of action

Reversibly inhibits COX 1 and 2 enzymes
causing decreased production of prostaglandin precursors

Onset Peak Duration

onset 30 mins, duration 6 hours

Physiological effects

As an anti-inflammatory, anti-pyretic and mild analgesic

Adverse Effects Toxicity

Worsen renal function by inhibiting PGE2 and causing vasoconstriction.
 risk of thromboembolic events.
Increased risk of GI bleeding and ulceration, GORD.
Impair platelet function
May reduce the beneficial eff¬ects of aspirin

Absorption

Rapidly absorbed
85% bioavailability

Distribution

pKa 4.5, weak acid therefore mostly unionised, abs via gut and SB

Protein binding

99% protein bound (may displace highly protein bound drugs such as warfarin altering PD properties)

Volume of distribution

Very small Vd 0.1L/kg

Metabolism

hepatic via oxidation

Excretion

excreted as metabolites in urine 1% unchanged

Half-life

half life 2-3 hours

Route And Dose

Tablets for PO/PR