Which are responsibilities of the FDA? (Select all that apply.)

a) The FDA is responsible for overseeing the testing of drugs for harmful effects, including preclinical trials and clinical trials, to ensure that drugs do not cause unsafe side effects.

b) The FDA ensures that drugs have accurate labeling, including correct dosage, potential side effects, contraindications, and proper use.

c) The FDA does not guarantee that a drug will be free from adverse reactions. While they regulate and monitor drugs, adverse reactions can still occur after approval, and it is the responsibility of healthcare professionals and the manufacturer to monitor for these post-marketing.

d) The FDA does not ensure drug affordability; the pricing of drugs is influenced by many factors, including market forces, healthcare policies, and manufacturer decisions.

e) The FDA ensures that drugs are effective by overseeing clinical trials to demonstrate that the drug has the intended therapeutic effects for its indicated use.

A. Distribution refers to the movement of the drug from the bloodstream into tissues and organs, but it does not explain why only a portion of the medication reaches the tissues.

B. The first-pass effect occurs when an orally administered drug is metabolized by the liver before reaching systemic circulation. Aspirin, when taken orally, undergoes significant metabolism in the liver, reducing the amount of active drug available to exert its therapeutic effect. This explains why only a portion of the drug reaches the tissues.

C. Reduced absorption can limit drug availability, but aspirin is generally well absorbed in the gastrointestinal tract. The primary reason for reduced drug availability in this case is metabolism by the liver, not poor absorption.

D. Gastrointestinal circulation involves the enterohepatic recycling of some drugs, but it does not explain why only a portion of aspirin reaches systemic circulation. The first-pass effect is the primary factor.