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MUSCULO-SKELETAL SYSTEM › OTHER DRUGS FOR DISORDERS OF THE MUSCULO-SKELETAL SYSTEM › OTHER DRUGS FOR DISORDERS OF THE MUSCULO-SKELETAL SYSTEM › Quinine and derivatives
quinine, combinations with psycholeptics
M09AA72
Forms & Strengths
- Fixed-dose combination tablets containing quinine and psycholeptic agents (e.g., diazepam or other sedatives)
- Available in various regional strengths typically combining 100mg to 300mg quinine with low-dose psycholeptics
Adult Dosing
- Nocturnal leg cramps: 1 tablet at bedtime, as directed by regional prescribing guidelines
- Duration of treatment should be periodically reassessed due to safety concerns
Pediatric Dosing
- Safety and efficacy in pediatric patients have not been established
- Use in children is generally contraindicated or not recommended
Indications
- Treatment and prevention of nocturnal leg cramps in adults
Mechanism of Action
- Quinine decreases the excitability of the motor endplate and increases the refractory period of skeletal muscle
- Psycholeptic component acts as a central nervous system depressant to reduce nocturnal discomfort and adjunctively manage associated anxiety or sleep disturbance
Contraindications
- Known hypersensitivity to quinine, cinchonine, or psycholeptic components
- Pre-existing cardiac arrhythmias (e.g., prolongation of QT interval, complete heart block)
- Glucose-6-phosphate dehydrogenase (G6PD) deficiency
- Myasthenia gravis
- History of quinine-induced thrombocytopenia or blackwater fever
- Concomitant use with strong CYP3A4 inhibitors or drugs known to prolong the QT interval
Adverse Reactions
- Cinchonism (tinnitus, impaired hearing, headache, nausea, visual disturbances)
- Hematological effects (thrombocytopenia, leukopenia, hemolytic anemia)
- Hypersensitivity reactions (pruritus, rash, urticaria, angioedema)
- Central nervous system effects from the psycholeptic component (drowsiness, dizziness, confusion)
- Gastrointestinal distress (diarrhea, abdominal pain, vomiting)
Drug Interactions
- Strong inhibitors or inducers of CYP3A4 alter quinine plasma concentrations
- Additive QT interval prolongation with antiarrhythmics, antipsychotics, and macrolide antibiotics
- Increased risk of central nervous system depression and sedation when combined with other psycholeptics, opioids, or alcohol
- Potential enhancement of neuromuscular blocking agents
- May increase plasma concentrations of digoxin and warfarin
Curated Content: Needs Vetting Before Put to Clinical Use