Pharmacology Interactions

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Questions and Answers

What effect does quinidine have on tubular reabsorption?

Has no effect on passive reabsorption

Decreases passive reabsorption

Increases active reabsorption

Increases passive reabsorption (correct)

What happens to the plasma levels of acidic drugs when Probenecid is administered with Quinolones?

They decrease due to enhanced excretion

They fluctuate randomly

They remain unchanged

They increase due to inhibition of organic anion transporters (correct)

What type of interaction occurs when two drugs compete for the same active transport system in the renal tubules?

Transporter protein interaction (correct)

Drug binding interaction

Pharmacokinetic interaction

Pharmacodynamic interaction

What is the effect of aspirin on tubular reabsorption?

It decreases passive reabsorption Signup and view all the answers

What type of interaction alters the pharmacodynamics profile of a drug?

Pharmacodynamic interaction Signup and view all the answers

What is the primary mechanism of quinidine's effect on tubular reabsorption?

Increase in tubular passive reabsorption Signup and view all the answers

What is the mechanism by which verapamil increases digoxin absorption?

Inhibition of P-glycoprotein Signup and view all the answers

What is the effect of a basic environment on the absorption of a weak acid?

Decreased absorption Signup and view all the answers

What is the effect of salicylates on warfarin?

Increased risk of hemorrhage Signup and view all the answers

Which enzyme is responsible for the metabolism of 40% of drugs?

CYP3A4 Signup and view all the answers

Which of the following drugs can decrease the absorption of ketoconazole by increasing the pH of the gut?

All of the above Signup and view all the answers

What is the effect of enzyme induction on the activity of co-administered drugs?

Decreased activity Signup and view all the answers

What is the mechanism of interaction between antacids and tetracycline?

Chelation Signup and view all the answers

What is the time frame for enzyme induction to develop and wear off?

Up to 3 weeks Signup and view all the answers

Which of the following drugs can increase the rate of gastric emptying and absorption of paracetamol?

Metoclopramide Signup and view all the answers

What is the effect of rifampin on the absorption of digoxin?

Decreased absorption Signup and view all the answers

Which of the following drugs is an example of an enzyme inducer?

Rifampicin Signup and view all the answers

Which of the following is an example of a pH-dependent absorption interaction?

Ketoconazole and antacids Signup and view all the answers

What is the effect of anticholinergics on the absorption of drugs?

Delayed absorption Signup and view all the answers

Which of the following interactions involves the inhibition of a drug transporter protein?

Rifampin and digoxin Signup and view all the answers

Study Notes

Pharmacokinetic Interactions

Quinidine increases the risk of toxicity by increasing tubular passive reabsorption of the object drug.
Aspirin decreases the clearance of the object drug by decreasing tubular passive reabsorption.
Drugs that use the same active transport systems in the renal tubules can compete with each other for excretion.

Changes in Active Renal Tubular Excretion

Penicillins, Cephalosporins, and Quinolones can inhibit organic anion transporters (OATS), increasing the plasma levels of acidic drugs and potentially causing toxicity.
Probenecid can inhibit the excretion of acidic drugs, leading to increased plasma levels and potential toxicity.

Pharmacodynamic Interactions

Verapamil can increase digoxin absorption by inhibiting P-glycoprotein.

Distribution Interactions

Salicylates and Sulfonamides can displace warfarin from its binding sites, increasing the risk of hemorrhage.
Protein-binding interactions can occur when one drug competes with another for binding sites, depending on concentrations and affinities.

Metabolism Interactions

Enzyme induction can increase the activity of metabolizing enzymes, leading to increased metabolism of certain co-administered drugs.
Cytochrome P450 isoenzymes, particularly CYP3A4, are responsible for the metabolism of many drugs.
Enzyme induction may take up to 3 weeks to develop and wear off.
Examples of enzyme-inducing drugs include Phenobarbitone, Phenytoin, Carbamazepine, and Rifampicin.

Changes in Gl pH

Weak bases are more absorbable in basic environments.
Weak acids are more absorbable in acidic environments.
Antacids, H₂-receptor antagonists, and Proton pump inhibitors can decrease the absorption of ketoconazole by increasing the pH.

Adsorption, Chelation, and Other Complexing Mechanisms

Antacids and mineral supplements can decrease the absorption of tetracycline and ciprofloxacin by forming less soluble chelates.

Changes in Gut Motility

Anticholinergics agents can delay gastric emptying, decreasing the rate of drug absorption.
Prokinetic agents can increase gastric emptying, increasing the rate of drug absorption.
Propantheline can delay gastric emptying, decreasing the rate of absorption of paracetamol.
Metoclopramide and domperidone can increase gastric emptying, increasing the rate of absorption of paracetamol.

Inhibition or Induction of Drug Transporter Proteins

Rifampin can decrease digoxin absorption by inducing P-glycoprotein.

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Description

This quiz covers interactions between different drugs and their effects on the body. It includes questions on how certain drugs can affect the absorption and reabsorption of other drugs, leading to increased risk of toxicity.