Coartem tablets

Indications

• Osteoarthritis
• Rheumatoid arthritis
• Acute pain
• Chronic pain conditions
• Fever

Dosage

Children: Refer to the BNF for Children for specific dosing guidelines for children.

Adults: Refer to the BNF for specific dosing guidelines for adults.

Mechanism of action

Acematacin works by inhibiting the enzyme cyclooxygenase (COX), which is crucial in the biosynthesis of prostaglandins. Prostaglandins are lipid compounds that mediate inflammation, pain, and fever. By decreasing the production of these compounds, acematacin reduces inflammation and provides analgesic effects. The inhibition of COX activity leads to decreased prostaglandin levels, thereby alleviating symptoms associated with inflammatory conditions.

Pharmacodynamics

The pharmacodynamics of acematacin involves its action on COX enzymes, specifically COX-1 and COX-2. While COX-1 is involved in the maintenance of gastric mucosa and platelet aggregation, COX-2 is primarily expressed during inflammation. The selective inhibition of COX-2 by acematacin results in reduced inflammation and pain with a lower incidence of gastrointestinal side effects compared to non-selective NSAIDs. The onset of action is typically within hours of administration, providing prompt relief from symptoms.

Pharmacokinetics

Acematacin is well-absorbed after oral administration, with peak plasma concentrations typically occurring within 1 to 2 hours. It has a half-life of approximately 4 to 7 hours, allowing for multiple dosing throughout the day. The drug is metabolized in the liver, primarily via hydroxylation and conjugation, and is excreted through urine. Renal function may significantly influence the pharmacokinetics of acematacin, necessitating caution in patients with renal impairment.

Contra-indications

• Hypersensitivity to acematacin or any of its excipients
• Active gastrointestinal bleeding or peptic ulcer disease
• Severe renal impairment
• Severe hepatic impairment
• History of asthma, urticaria, or other allergic reactions after taking acetylsalicylic acid or other non-steroidal anti-inflammatory drugs (NSAIDs)

Adverse effects

• Gastrointestinal discomfort, including nausea, vomiting, and diarrhea
• Dizziness or headache
• Rash or other allergic skin reactions
• Renal toxicity, including acute kidney injury
• Hepatic enzyme elevation
• Cardiovascular events, including hypertension and edema

Interactions

• Increased risk of gastrointestinal bleeding when used with other NSAIDs, anticoagulants, or corticosteroids
• May reduce the effectiveness of certain antihypertensive medications
• Potential interaction with methotrexate, increasing toxicity risk
• Caution advised when used with lithium, as acematacin may affect renal clearance and increase lithium levels

Precautions

• Use with caution in patients with cardiovascular disease, liver or kidney dysfunction
• Monitor renal function in long-term use or in patients with pre-existing conditions
• Patients should be advised to report any signs of gastrointestinal bleeding, such as black stools or vomiting blood
• Avoid use in the elderly unless deemed necessary, as they may be more susceptible to adverse effects

Pregnancy

Acematacin is not recommended during pregnancy, especially in the third trimester, due to potential risks of fetal harm.

Breast-feeding

It is not known whether acematacin is excreted in human milk. Caution is advised when administering to breastfeeding mothers.

Storage

Store in a cool, dry place, away from direct sunlight. Keep out of reach of children.

Formulations

• Oral tablets
• Capsules
• Topical formulations