Which factor is most likely to contribute to reduced medication adherence?

A. Adverse effects of a drug are monitored after the drug is approved by the FDA: This describes a phase IV clinical trial, also known as post-marketing surveillance, where long-term safety and rare side effects are evaluated after public release.

B. The drug is administered to a small number of healthy volunteers to determine its safety: Phase I clinical trials primarily assess the drug’s safety, tolerability, pharmacokinetics, and dosage range. These studies usually involve a small group of healthy participants to identify potential side effects and establish safe dosing parameters.

C. The drug’s effects are compared to a placebo to determine its effectiveness: This is characteristic of a phase III clinical trial, where a large sample of patients receives the investigational drug or placebo to evaluate its efficacy and compare it to standard treatments.

D. The drug is administered to a large number of patients to assess effectiveness: Phase II and III trials focus on assessing effectiveness, with phase III involving the largest sample sizes. Phase I, however, emphasizes safety and dosage testing, not broad patient efficacy.

A. Antagonist: An antagonist is a drug that binds to a receptor without activating it, thereby blocking other substances from producing their effects. Naloxone works as an opioid receptor antagonist by displacing opioids like morphine or heroin and reversing their respiratory and CNS depressive effects.

B. Anticholinergic: Anticholinergic drugs block the action of acetylcholine in the parasympathetic nervous system. Naloxone does not act on cholinergic receptors; it specifically targets opioid receptors.

C. Agonist: An agonist binds to a receptor and activates it to produce a physiological response. Opioids like morphine are agonists because they stimulate opioid receptors, whereas naloxone blocks them, producing the opposite effect.

D. Mimetic: The term “mimetic” refers to a substance that imitates or enhances the effects of another agent or physiological process. Naloxone does not mimic opioid effects; it inhibits them, preventing activation of opioid receptors.