[Influence of foods on the absorption of antimicrobial agents]

Understanding the interaction between foods and antimicrobial agents is an aspect of therapy which may have an important clinical repercussion, which is why it must not be forgotten. This study reviews the interactions of foods with the anti-microbial agents which occur at the level of absorption, considering the mechanisms involved. The food-drug interaction can cause an increase, a decrease, or a delay in the bio-availability of the anti-microbial agents; foods may have no affect on the absorption of the anti-microbial agents, or they may improve the gastrointestinal tolerance. The Food and Drug Administration's bioequivalency criteria for considering whether or not there is an alteration in absorption have an orientative function, as generally all studies are conducted on healthy volunteers, but in clinical practice one must consider the physiological and pathological condition of the patient. The composition of the diet as well as the volume of liquid administered are other aspects which should be considered, as these may exert a different effect depending on the type of drug. After ingesting fatty foods, there is an increased absorption of albendazole, griseofulvin, itraconazole, and mebendazole. All foods but especially carbohydrates reduce the absorption of isoniazide. Among the anti-HIV drugs, the following must be administered on an empty stomach: didanosine, indinavir zalcitabine , and zidovudine ; lamivudine can be administered either on an empty or on a full stomach, because although food delays the absorption, it does not affect the amount absorbed; the absorption of stavudine is not affected by foods; ritonavir should be administered together with tile meals, and saquinavir must be administered after ingestion of food. It is advisable to administer clarithromycin together with foods, and azythromycin on an empty stomach; the same holds true for perfloxacin and rifabutine as for lamivudine.