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HIV NUTRITION UPDATE
VOLUME 7, ISSUE 2
FOOD - DRUG INTERACTIONS IN HIV/AIDS
(Continued from page 2)
 

Medical team members should be aware of interactions that are therapeutically important. Therapeutically important interactions: 1) change the effect of a medication; or 2) cause drug toxicity; or 3) affect normal nutritional status.

Patients should be assessed individually for the effect of food on drug action and the effect of drugs on nutritional status. Interactions can be caused or complicated by a variety of circumstances (Table 1). Poor patient compliance, in addition to prescribing by multiple physicians, add to the risk.

Existing malnutrition also places people at greater risk for drug-nutrient interactions. Protein alterations, specifically low albumin levels, and changes in body composition secondary to malnutrition may affect drug disposition by altering protein binding and drug distribution. Patients with AIDS and significant anorexia and wasting are especially at risk. Drug disposition can be affected by alterations in the gastrointestinal tract, such as vomiting, diarrhea, hypochlorhydria, mucosal atrophy, and motility changes. 

MECHANISMS OF FOOD-DRUG INTERACTIONS

Food-drug interactions may be divided into two broad types: pharmacodynamic interactions that affect the pharmacologic action of the drug and pharmacokinetic interactions, which affect the movement of the drug into, through or out of the body. 

PHARMACODYNAMICS

Pharmacodynamics is the study of the biochemical and physiologic effects of a drug or combination of drugs. Substances with similar or opposing action, such as food additives or individual nutrients can affect the action of a drug. The biological response to a drug may be enhanced or reduced by the presence of such substances.
 
TABLE 1. CAUSES OF FOOD-DRUG INTERACTIONS
Alcohol intake  Allergies or intolerance Prescribing by multiple physicians
Drugs of abuse Excipients in drugs or food Herbal/natural products
Malnutrition Non-nutrients in food Nutritional status
Polypharmacy Tube feeding Nutritional supplements
Special diets  Poor patient compliance Underlying illness
Genetics
 
  
 

PHARMACOKINETICS OR NUTRIENT KINETICS

Pharmacokinetics or nutrient kinetics describes the movement of a drug or nutrient through the body by absorption, distribution, metabolism (biotransformation), and excretion of the drug.

Absorption is the process by which the drug/nutrient moves from the site of administration (e.g. oral, nasal, rectal or parenteral) to systemic circulation. Distribution  is the movement from one organ system to another. Metabolism is the process of chemical change by the action of enzymes which creates metabolites of the drug or nutrient. Excretion occurs when drug, nutrient or metabolites are removed from the body, primarily through the kidneys. 
 
 

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9/23/2002