7. Food-Drug interactions

Effect of food on drugs in general

• Acute

• increase or reduction of known effects and side-effects

• often recognized

Effect of drugs on foods in general

• Slow manifest

• Outcome(s) related to nutrient(s)/nutrition

• Often missed.

Main caues of food-drug interactions

• Interactions prior to administration

• interactions in the gastro-intestinal tract

• Interference of uptake from the GI tract

• Modulation of drug biotransormation

• … (other pharmocokinetic effects)

• Pharmocodynamic interaction

Basics of oral drug absorption

• Mostly in duodenum

• Drug should be in dissolved state

• Often by passive diffusion

• Sometimes active transport involved

• Lipids soluble compounds with lipids

• Metabolsim in intestinal wall can be considerable

Squinavir and indinavir

Chelation of active compound leading to poor solublity and absorption

Chinolones

Taking a drug on a full or an empty stomach?

• Full stomach = delayed gastric emptying → decreased absorption rate

• Effect on bio-availability depends on:

  • Acid stability

  • Dissolution behavior in stomach

Effects of high fat meals on drug absorption

• Fat delays gastric emptying → absorption also delayed

• With hydrophilic compounds, effects on bio-availability usually less pronounced

• Lipophilic compounds often affect bio-availability, but not always in a similar direction

Two effects and their names as a result of a high fat meal

• Isotretinoin: bioavailability increases with fat (advice: do not vary in dietary fat)

• Tacrolimus: reduced absorption by fat > also advised to keep dietary fat constant

Four classes of biopharmaceuticals

• F= bioavailability

• Class 1 = like paracetamol

• Class 2 = lipophilic

• Class 3 = likely for stomach infections

• Class 4 = brick dust, does not dissolve in anything

Levodopa

• Taken for patients with Parkinson’s disease

• Taken up via LNAA transporter in proximal small intestine & via same transporter over BBB

• LNAA transporter: primarily for neutral AAs like tryptophan, tyrosine and BCAAs

• Practice: take levodopa half hour or 1 hour after a meal

Food interactions at CYP450 level

remember grapefruit, sint john’s wort.

Tamoxifen

Curcumin can affect tamoxifen.

• Co-treatment with curcumin could lower endoxifen concentrations below the threshold for efficacy in extensive CYP2D6 metabolizers

How may drugs affect taste/eating/digestion

• Effects of drugs in the oral cavity

• Effects on taste or sense of smell

• Effects on appetite or satiety

• Various effects in the GI tract

• Metabolic effects

• Disturbance of absorption or metabolism of micronutrients

• Disturbance of microbiota

Examples of side-effects of drugs in the oral cavity

• Diverse forms of ulcera, opportunistic infections, etc.

• Erythema, swelling of gingiva, salivary glands

• Tongue abnormalities

• Problems with (false-)teeth

• Taste and/or smell disorders

• Dry mouth (xerostomia)

Xerostomia

• Dry mouth

• Common in elderly

• Often associated with/caused by drug use

• Long list of compounds potentially involved

Drugs that may affect appetite

• CNS compounds but also others e.g.:

  • TCAs, benzodiazepines, corticosteroids and valproate stimulate appetite

  • SSRIs and topiramate inhibit appetite

• Be aware of indirect effects

Effects of drugs on absorption or elimination of nutrients