What are the effect of food on drug absorption?

 

 Effect of food nutrient on drug/ Food drug interaction:

1.Effect of food/ nutrient on drug absorption:

Drugs whose absorption decrease in presence of food are stated below

• Anti-osteoporosis drug Alendronate (Fosamax) absorption decrease by 60% in presence of coffee, juice. It is recommended to take 2h or 30min before meal.

• High fiber diet decrease absorption of Tricyclic anti-depressant Amitriptyline (Elavil)

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Chelation between drug:

• Ciprofloxacin (Cipro) form insoluble complexes  with calcium ( in dairy products), Calcium, magnesium, iron, zinc, aluminum ( supplements), magnesium, calcium, aluminum ( antacid ).

Drugs whose absorption enhance in presence of food:

Some drugs are known to have increased or enhanced absorption when taken with food. This phenomenon is often associated with oral medications, and it can have significant implications for their effectiveness and safety. Here are a few examples of drugs that may have enhanced absorption when taken with food:

Lipid-Soluble Medications: Many drugs that are lipophilic (soluble in lipids or fats) tend to be better absorbed when taken with food. This is because the presence of dietary fats can increase the solubility of these drugs, allowing for better absorption. Examples of such drugs include certain antibiotics (e.g., amoxicillin, azithromycin), lipid-lowering drugs (e.g., statins), and some vitamins and minerals (e.g., vitamin D, vitamin K).

Protease Inhibitors: Some antiviral medications, such as protease inhibitors used in the treatment of HIV, are more effectively absorbed when taken with a meal that contains fats.

Griseofulvin: This antifungal medication is known to have improved absorption when taken with a high-fat meal.

Cyclosporine: An immunosuppressant drug often used in organ transplantation, cyclosporine's absorption can be enhanced when taken with food, particularly a high-fat meal.

Tacrolimus: Another immunosuppressant used in transplant patients, tacrolimus can also benefit from food-related enhanced absorption.

Some Psychiatric Medications: Some antidepressants, antipsychotics, and mood stabilizers may be recommended to be taken with food to improve their absorption and reduce the risk of gastrointestinal side effects.

• Cefuroxime axetil (Ceftin) used to treat wide range of bacterial infection by stopping growth of bacteria absorption increase in presence of food.

• Cinacalcet (Sensipar) absorption increase by 82% in presence of high fat meal.

2.Effect of food/nutrient on drug distribution:

• Hypoalbuminea ( less than 3g/dl albumin ) cause decrease in binding site of drug. Phenytoin (Dilantin)-90%, Warfarin (Coumadin)-99% bound. Higher amount of unbound free fraction cause higher pharmacological effect.

3.Effect of food on drug excretion:

• Lithium ( Eskalith) and sodium are abs0rbed at same site in kidney. If sodium level is low sodium/lithium retention increase. If sodium intake is high sodium/lithium excretion increase.

Renal Excretion:

• Absorption and bioavailability: Food can affect the absorption of drugs in the gastrointestinal tract. Some drugs are better absorbed when taken with food, while others are absorbed more rapidly when taken on an empty stomach. This can impact the drug's overall exposure in the body and, consequently, its excretion.
• Altered pH: Some foods can change the pH of the stomach or urinary tract, which may influence the ionization of drugs and, in turn, their excretion.
• Competition for renal transporters: Food components or other drugs may compete for renal transporters, affecting the rate at which a drug is excreted. For example, some drugs are excreted through organic anion transporters (OATs) or organic cation transporters (OCTs) in the kidneys, and food components may compete with the drug for these transporters.

Biliary Excretion:

• Hepatic metabolism: The presence of food in the gastrointestinal tract can influence the metabolism of drugs in the liver. For some drugs, metabolism can enhance their excretion through the bile.
• Enterohepatic circulation: Some drugs undergo enterohepatic circulation, which involves excretion into the bile, reabsorption in the intestine, and then re-excretion. The timing and composition of meals can impact this process, potentially altering the rate of drug excretion.

4.Effect of food on medication metabolism:

• Use of food and propranolol (Inderal) increase serum level of drug, as first pass effect is reduced.BC 

• Grapefruit inhibit metabolism of drug such as Amiodarone ( Cordarone) inhibit activity of cytochrome P450 3A4 in intestinal wall. Serum drug level increase may become toxic.

• Natural product St John's Wort used as anti-depressant induce activity of cytochrome P450 3A4 which lead to low blood drug level which lead to therapeutic failure. Drug effected by St Johns Wort are: oral contraceptive, immunosuppressant Cyclosporine (NE oral), Tacrolimus ( Prograf ), Antiretroviral Indinavir (Crixivan).

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