Quinine Aluminium hydroxide

Aluminium/magnesium hydroxide gel reduces the absorption of quinine from the gut of rats and reduces quinine blood levels by 50 to 70%. This appears to occur because aluminium hydroxide slows gastric emptying, which reduces absorption, and also because magnesium hydroxide forms an insoluble precipitate with quinine. However, there seem to be no clinical reports of a reduction in the therapeutic effectiveness of quinine due to the concurrent use of antacids. 

Bind to other drugs that are administered within 1 or 2 hours of the antacid, This process results in reduced availability of the co-administered drug for absorption, For example, the chelation of tetracyclines (e.g, tetracycline, doxycycline) will decrease their absorption by up to 90%, Avery similar process - precipitation - occurs with drugs such as quinine with aluminium and magnesium hydroxide preparations, which results in a decreased absorption of quinine, It has to be noted that the absorption of fluoroquinolones (e g. ciprofloxacin, norfloxacin, ofloxacin, enoxacin, perfloxacin i will be decreased by 60-75% if they are co-administered with divalent and trivalent cations. Patients are recommended not to take these divalent and trivalent cationic preparations until fluoroquinolone therapy is discontinued. 

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