12 Questions
How can the presence of other substances in the gastrointestinal tract (GIT) impact drug bioavailability?
Decrease the amount of drug that reaches systemic circulation
Which factor is primarily responsible for the first-pass effect in drug metabolism?
Extensive metabolism by the liver
What is a possible consequence of low bioavailability of a drug?
Decreased drug potency
Which route of drug administration is likely to pass the first-pass effect?
Oral
How does drug metabolism affect the bioavailability of a medication?
May decrease the amount of active drug available
Which factor can affect the bioavailability of a drug?
Enterohepatic recycling
What does pharmacokinetics study?
Drug absorption, distribution, metabolism, and excretion
What is the primary organ responsible for the first-pass effect?
Liver
Which factor does NOT directly impact the bioavailability of a drug?
The molecular weight of the drug
Which route of drug administration is LEAST likely to be affected by the first-pass effect?
Transdermal administration
What is the term used to describe the fraction of a drug that is not metabolized during its first pass through the liver?
Fraction available
Which of the following factors can INCREASE the bioavailability of a drug?
Decreased metabolism during the first pass through the liver
Study Notes
Factors Affecting Bioavailability
- Presence of other substances in the GIT (Gastrointestinal Tract) can alter drug bioavailability
Bioavailability of Various Drugs
- Aspirin: 0.5 (low bioavailability)
- Amoxicillin: 0.6 (moderate bioavailability)
- Diclofenac Sodium: 0.63 (moderate bioavailability)
- Ciprofloxacin: 0.7 (moderate bioavailability)
- Paracetamol: 0.79 (high bioavailability)
- Fluconazole: 0.9 (high bioavailability)
- Metronidazole: 0.99 (very high bioavailability)
- Phenytoin: 1 (complete bioavailability)
Pharmacokinetics
- Study of the time course of drug absorption, distribution, metabolism, and excretion
- Bioavailable fraction is determined by:
- Fraction of drug absorbed from the gastrointestinal tract
- Fraction of drug that escapes metabolism during its first pass through the liver
Test your knowledge on how drug bioavailability can be affected by the presence of other substances in the gastrointestinal tract (GIT). Explore how various compounds can alter the absorption of drugs in the body.
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