MERSYNDOL

What it is

MERSYNDOL is a plain white round biconvex tablet containing 30 mg of codeine phosphate hemihydrate. Codeine phosphate hemihydrate is an opioid analgesic that binds with stereospecific receptors at many sites within the central nervous system to alter processes affecting both the perception of pain and the emotional response to pain. Its analgesic effect is thought to be due to its partial metabolic conversion to morphine. Codeine has about one-sixth the analgesic activity of morphine.

Approved indications

— Short-term management of severe pain for which other treatment options have failed, are contraindicated, not tolerated or are otherwise inappropriate to provide sufficient management of pain.

Dosing overview

Adults: 30 to 60 mg every four to six hours (usual dose 30 mg). If 60 mg of codeine every four to six hours fails to relieve pain, larger doses rarely succeed and may give rise to restlessness and excitement. Initial dosing requirements will depend on medical and analgesic history of the patient, patient's age, weight and severity of pain. It may need to be reduced in patients who are elderly or debilitated.

Key safety warnings

Serious, life-threatening or fatal respiratory depression may occur with the use of MERSYNDOL. Be aware of situations which increase the risk of respiratory depression, modify dosing in patients at risk and monitor patients closely, especially on initiation or following a dose increase. Concomitant use of opioids with benzodiazepines, gabapentinoids, antihistamines, tricyclic antidepressants, antipsychotics, cannabis or other central nervous system depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. Patients should not drink alcohol while taking MERSYNDOL. MERSYNDOL contains the opioid codeine and is a potential drug of abuse, misuse and addiction. Addiction can occur in patients appropriately prescribed MERSYNDOL at recommended doses. The risk of addiction is increased in patients with a personal or family history of substance abuse (including alcohol and prescription and illicit drugs) or mental illness. The risk also increases the longer the drug is used and with higher doses. MERSYNDOL is contraindicated for use in patients who are CYP2D6 ultra-rapid metabolisers. Codeine is metabolised by the liver enzyme CYP2D6 into morphine, its active metabolite. If the patient is an extensive or ultra-rapid metaboliser there is an increased risk of developing side effects of opioid toxicity even at commonly prescribed doses. These patients convert codeine into morphine rapidly resulting in higher than expected serum morphine levels.

Contraindications

MERSYNDOL is contraindicated in patients with hypersensitivity to any ingredient. Due to codeine's structural similarity to morphine and oxycodone, patients experiencing systemic allergy (generalised rash, shortness of breath) to these drugs should not receive codeine. Codeine is contraindicated in respiratory depression (for example, acute asthma, acute exacerbations of chronic pulmonary disease), especially in the presence of cyanosis and excessive bronchial secretion, and after operations on the biliary tract. Codeine is contraindicated in the presence of acute alcoholism, head injuries, and conditions in which intracranial pressure is raised. Administration is contraindicated in patients taking monoamine oxidase inhibitors (MAOIs) or within ten days of stopping such treatment. MERSYNDOL is contraindicated for use in patients who are CYP2D6 ultra-rapid metabolisers, younger than 12 years, or aged between 12–18 years in whom respiratory function might be compromised, including post tonsillectomy or adenoidectomy for obstructive sleep apnoea, due to an increased risk of developing serious and life-threatening adverse reactions. MERSYNDOL is contraindicated during breastfeeding.

Regulatory history

MERSYNDOL was first approved on 1 October 1992. MERSYNDOL tablet blister pack was first listed on the ARTG on 1991-07-08 under licence category RE.