With or without food
One of my favorite songs when I was young was 'With or Without You' by U2. The chorus goes:
'With or Without You, With or Without You, oh, I Can't Live, With or Without You'
Guess what? If we understand our #pharmacokinetics #concepts (#5), we can predict the oral absorption of drug with or without food. The chorus of the new song will go:
'With or Without Food, With or Without Food, oh, I Can Predict, With or Without Food'
As a recap, the absorption of all acidic, basic and neutral drugs is faster from the small intestine than from the stomach. To revise this concept, you may refer to article #4.
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Consequently, how fast the stomach empties its content into the small intestine (aka gastric emptying rate) becomes an important controlling step to regulate the rate and extent of systemic absorption of orally-administered drugs. During fasting (no food), the average stomach transit time of a tablet is around 1 hour. During fed (heavy breakfast), the average stomach transit time can go up to 7 hours! For a membrane-permeable drug that is sparingly soluble in both gastric and intestinal fluids, administering the drug with food will help to improve its absolute oral bioavailability (F). #True or #False?
#True. With a fixed short transit time in the small intestine (3-4 hours), the slow release of drug from the stomach under fed condition, increases the time for drug to dissolve before entering the intestine, thereby favoring increased oral bioavailability. The bile salts that are released after a high fat meal further act as surfactants and enhance solubility of the sparingly soluble drug.
In summary, food slows down gastric emptying rate, improves the dissolution of sparingly soluble drug, reduces its rate but increases its extent of absorption and increases its oral bioavailability. The higher oral bioavailability will lead to higher systemic exposure (AUC) which in turn correlates with the pharmacology (drug) effects. Of course, this is just one scenario and there are many other scenarios related to pro-drugs, soluble drugs, enteric-coated drugs, sustained-released drugs etc.
In conclusion, it is important to appreciate that when pharmacists and physicians advise us to consume oral drugs with or without food, we need to be compliant as food has important effects on pharmacokinetics. If you like to learn more about the 'very' basic concepts in?#pharmacokinetics, let me know and follow my future posts.