Question

Discuss how gastric and intestinal motility influence drug absorption.

Discuss the impact antacids have on drug absorption.

Discuss additive, synergistic(potentiation), and antagonist drug effect. Why is it important for the nurse to understand these concepts?

Explain agonists and antagonists. Include nonspecific and nonselective in your answer.

Answer 1

(i) EFFECT OF GASTRIC AND INTESTINAL MOTILITY ON DRUG ABSORPTION:-
-Gastrointestinal (GI) motility is a physiological factor that affects drug absorption by controlling a drug's residence time in the GI tract.
-Increased GI facilitate drug absorption by mixing intestinal contents and thereby bringing the drug into more intimate contact with the mucosal surface.
- Vice versa may also occur in that an increase in motility may reduce contact time in the upper portion of the intestine and a decrease GI motility increase absorption by increasing contact time.

(ii) IMPACT OF ANTACIDS ON DRUG ABSORPTION:-
-Antacids interfere with gastrointestinal(GI) drug absorption by either increasing or decreasing the rate and quantity of drug absorbed.
-Antacids bring alteration of ionization state or solubility, factors dependent upon pH.
-Antacids delay gastric emptying and are capable of chelation and adsorption with susceptible products.
-Thus antacid have several effect on drug absorption.

(iii) a)ADDITIVE EFFECT:-
-It occurs when two or more "like" drugs are combined.
-An additive effect may be intentional or may unintentionally cause harm.
b) SYNERGISTIC EFFECT:-
-This type of effect occurs when two or more "unlike" drugs are used together to produce a combined effect.
-For Example a beneficial synergistic effect occurs on combination of penicillin G and an aminoglycoside antibiotic.
c) ANTAGONIST EFFECT:-
- This type of effect is the opposite of a synergistic effect.
- It results in a therapeutic effect that is less than the effect of either drug alone because the second drug either diminishes or cancels the effects of the first drug.
- Antagonistic interactions can also occur at receptor sites.

(iv) AGONIST AND ANTAGONIST:-
-Agonist is a chemical that binds to a receptor and activates the receptor to produce a biological response. While an Antagonist blocks the action of the agonist.
- DIFFERENCE BETWEEN AGONIST AND ANTAGONIST:-
a)Agonist and antagonist act in opposite directions. When agonist produces an action, antagonist opposes the action.
b) Agonist stimulate an action while antagonists, do nothing.
c)Agonist binds to a receptor site and causes a response whereas an antagonist works against the drug and blocks the response.