Why do systemic enzymes need to be taken on an empty stomach? by Connie b. Dellobuono

Answer by Connie b. Dellobuono:

Take your digestive enzymes and acidophilus before a meal to increase bioavailability and be present in our body before we ingest food so that these enzymes and supplements can be more beneficial. Do take fat-rich meal with Vit E, D, K and A. And always have Vitamin C rich foods with meals as it helps in the absorption of nutrients.

Do not eat/drink grapefruit when taking any meds/drugs as it doubles their potency.
food drug interaction p2food drug interactionFood and absorption of drugs/supplements

Food and its constituents may have a significant effect on both the rate and extent of absorption of drugs after oral administration. Understanding the effect of meals on medicines enables health professionals to advise patients about taking medicines with or without food. Co-administration of drugs with food generally delays drug absorption. However, meals may have a variable effect on the extent of absorption – depending on the characteristics of the meal, the drug and its formulation. Some drugs have strict guidelines about when they should be taken in relation to meals. Generally, patients should be advised to take their medicines consistently at the same time with respect to meals.

Bioavailability and drug interactions with food

Understanding the possible clinical implications of taking medicines with or without a meal is important for achieving quality use of medicines. Although the effect of food is not clinically important for many drugs, there are food-drug interactions which may have adverse consequences. Often these interactions can be avoided by advising the patient to take their medicines at the same time with respect to meals.

The effect of food on absorption

The formulation of a drug influences its absorption. Food can affect both the rate and extent of absorption (Table 1).

Rate of absorption

Meals slow down gastric emptying and this can delay drug absorption. The composition of the meal influences the rate of gastric emptying – high fat meals lead to delayed gastric emptying. A delay in the drug reaching the small intestine can delay its subsequent absorption into the systemic circulation. Based on these observations, oral administration of a medicine under fasting conditions is often recommended when rapid absorption (and hence rapid onset of therapeutic effect) is needed. For most medicines, especially those used for chronic conditions, a delay in the onset of absorption is of no clinical consequence as long as the amount of drug absorbed is unaffected.

Extent of absorption

Food has the potential to either increase or decrease the extent of drug absorption. Understanding food-drug interaction mechanisms enables the clinician to provide appropriate advice to patients about taking medicines with respect to the timing and composition of meals.

The effect of food depends on the physicochemical and pharmacokinetic characteristics of the drugs.1 The clinical significance of the effect will in turn depend on the pharmacodynamic characteristics of the drug. For example, the poorly water soluble antiretroviral drug saquinavir should be taken with food to allow bile enhancement of its dissolution which then facilitates absorption. The extent of absorption is more than doubled by taking saquinavir after a full cooked breakfast. Taking saquinavir on an empty stomach reduces its bioavailability and could lead to therapeutic failure.1

Delayed gastric emptying after a meal and the associated gastric acid secretions can reduce the bioavailability of some medicines that are acid labile. The constituents of a meal may also specifically interact with drugs (Table 2). Calcium and other cations in food can form insoluble chelates with some medicines preventing their optimal absorption. Bisphosphonates are therefore recommended to be taken with plain water to prevent the formation of chelates which significantly reduce bioavailability.


Aust Prescr 2006;29:40-2 | 1 April 2006 | http://dx.doi.org/10.18773/austprescr.2006.026

Andrew McLachlan and Iqbal Ramzan, Faculty of Pharmacy, University of Sydney, NSW

Why do systemic enzymes need to be taken on an empty stomach?