Quinine
Mechanism :
Quinine inhibits nucleic acid synthesis, protein synthesis, and glycolysis in Plasmodium falciparum and can bind with hemozoin in parasitized erythrocytes. However, the precise mechanism of the antimalarial activity of quinine sulfate is not completely understood.
Indication :
Contraindications :
Quinine sulfate is contraindicated in patients with a prolonged QT interval, in patients with glucose-6-phosphate dehydrogenase (G-6-PD) deficiency, in patients with myasthenia gravis, in patients with known hypersensitivity to quinine, in patients with known hypersensitivity to mefloquine or quinidine because cross-sensitivity to quinine has been documented, in thrombotic thrombocytopenic purpura (TTP) or hemolytic uremic syndrome (HUS), hemoglobinemia and optic neuritis.
Dosing :
Oral:
30 mg/kg/day (sulphate) in 3 divided doses for 7 days.
IV Infusion:
Over 4 hours initial loading dose of 20 mg/kg (Max: 1.4 gm), then 10 mg/kg (Max: 0.7 gm) every 12 hours for 48 hours and then maintenance to oral.
Adverse Effect :
The most common adverse events associated with quinine use are a cluster of symptoms called “cinchonism”, which occurs to some degree in almost all patients taking quinine. Symptoms include headache, vasodilation and sweating, nausea, tinnitus, hearing impairment, vertigo or dizziness, blurred vision, and disturbance in color perception. More severe symptoms of cinchonism are vomiting, diarrhoea, abdominal pain, deafness, blindness, and disturbances in cardiac rhythm or conduction. Most symptoms of cinchonism are reversible and resolve with discontinuation of quinine.
Interaction :
Antacids: Antacids containing aluminium and/or magnesium may delay or decrease absorption of quinine.
Erythromycin (CYP3A4 inhibitor): Erythromycin was shown to inhibit the metabolism of quinine. Therefore, concomitant administration of erythromycin with quinine sulfate is likely to increase plasma quinine concentrations and should be avoided.
Rifampin (CYP3A4 inducer): the concomitant administration of rifampin with quinine sulfate should be avoided.
Tetracycline: Although tetracycline may be concomitantly administered with quinine sulfate, patients should be monitored closely for adverse reactions associated with quinine sulfate.
Amiodarone, Flecainide, Halofantrine, Cisapride and certain Antipsychotics: increased risk of arrhythmias.
Cimetidine: Increased plasma-quinine concentration.
Digoxin: Plasma concentration of digoxin is increased.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-50 | Malaria: 5–7 mg/kg every 8 hours Cramp: Dose as in normal renal function |
| 10-20 | Malaria: 5–7 mg/kg every 8–12 hours Cramp: Dose as in normal renal function |
| <10 | Malaria: 5–7 mg/kg every 24 hours Cramp: Dose as in normal renal function |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Dialysed. Dose as in GFR<10 mL/ min |
| HD | Dialysed. Dose as in GFR<10 mL/ min |
| HDF/High flux | Dialysed. Dose as in GFR<10 mL/ min |
| CAV/VVHD | Not dialysed. Dose as in GFR=10– 20 mL/min |
Hepatic Dose :
Mild to moderate hepatic impairment: No dose adjustment is required, monitor response closely.
Severe hepatic impairment: Use is not recommended.