Oramorph Drug Interactions

Sedative medicines such as benzodiazepines or related drugs: The concomitant use of opioids with sedative medicines such as benzodiazepines or related drugs increases the risk of sedation, respiratory depression, coma and death because of additive CNS depressant effect. The dose and duration of concomitant use should be limited (see Precautions).
Other CNS depressants: The concomitant application of tranquilisers, anaesthetics (see Precautions), hypnotics, sedatives, tricyclic antidepressants, antipsychotics, sedating H1 antihistamines (e.g. hydroxyzine), or alcohol increases the CNS depressing effect of morphine, especially the depressive effect on respiration. Death may occur. If used concurrently with CNS depressants, dosage adjustment may be required.
Phenothiazines: Phenothiazine antiemetics may be given with morphine. However phenothiazines may augment respiratory depression and may increase risk of hypotension as additive hypotensive effects may occur (see Precautions). Concurrent use of phenothiazines may enhance sedative effects, but at the same time, some phenothiazines (promethazine) have an antianalgesic effect.
Oral Anticoagulants: Morphine may enhance response to anticoagulants such as warfarin (coumadin); however, short-term use does not likely have a significant effect.
A delayed and decreased exposure to oral P2Y12 inhibitor antiplatelet therapy (e.g. clopidogrel, prasugrel, ticagrelor) has been observed in patients with acute coronary syndrome treated with morphine. This interaction may be related to reduced gastrointestinal motility and apply to other opioids. The clinical relevance is unknown, but data indicate the potential for reduced P2Y12 inhibitor efficacy in patients co-administered morphine and a P2Y12 inhibitor (see Precautions). In patients with acute coronary syndrome, in whom morphine cannot be withheld and fast P2Y12 inhibition is deemed crucial, the use of a parenteral P2Y12 inhibitor may be considered.
Medicines with anticholinergic effect: Antihistamines, antiemetics, antimuscarinics (e.g. drugs for treatment of Morbus Parkinson) can enhance anticholinergic side effects of opioids and may result in increased risk of severe constipation and/or urinary retention.
Monoamine oxidase inhibitors: If monoamine oxidase inhibitors are used within 14 days prior to the initiation of morphine or these are administered concomitantly with morphine life-threatening effects on the central nervous system, respiration or circulation can occur (see Contraindications).
Cimetidine: Cimetidine inhibits morphine metabolism.
Skeletal Muscle Relaxants: Morphine can enhance the effect of muscle relaxants.
Rifampicin: Rifampicin can reduce the plasma concentration of morphine and decrease its analgesic effect (see Precautions).
Levallorphan/Naloxone: Antagonise the analgesic, CNS and respiratory depressant effects of opioid analgesics and may precipitate withdrawal symptoms in physically dependent patients: dosage of levallophan or naloxone should be carefully titrated when used to treat opioid overdosage in dependent patients.
Methadone or Opioid Agonist Analgesics: Additive CNS depressant, respiratory depressant and hypotensive effects may occur if two or more opioid agonist analgesics are used concomitantly.
Neuromuscular Blocking Agents: Respiratory depressant effects of neuromuscular blocking agents may be additive to central respiratory depressant effects of opioid analgesics; caution is recommended when an opioid drug is administered during surgery or in the immediate post-operative period to a patient who has received a neuromuscular blocking agent.