A 21-year-old male has recently begun pimozide therapy for Tourette disorder. His parents bring him to the emergency department. They describe that he has been having 'different-appearing tics' than before, such as prolonged contraction of the facial muscles. While being examined, he experiences opisthotonos (type of extrapyramidal spasm of the body in which the head and heels are bent backward and the body is bowed forward). Which of the following drugs would be beneficial in reducing these symptoms?

Correct Answer: A

Rationale: Pimozide, a D2 antagonist for Tourette's, can cause acute dystonia (prolonged muscle contractions, opisthotonos) as an extrapyramidal symptom due to dopamine blockade. Benztropine, an anticholinergic, restores dopamine-acetylcholine balance in the basal ganglia, rapidly relieving dystonia by reducing cholinergic overactivity. Bromocriptine, a dopamine agonist, might theoretically help but isn't standard for acute EPS. Lithium treats bipolar disorder, not EPS. Prochlorperazine, an antipsychotic, worsens dystonia. Risperidone adds D2 blockade. Benztropine's proven efficacy in acute dystonia, per clinical guidelines, makes it the best intervention here.

Correct Answer: B

Rationale: Fluoxetine, an SSRI, treats depression but interacts with alcohol, worsening sedation or mood , indicating a teaching gap'clients must avoid it. Feeling better in weeks aligns with SSRI onset. Reporting suicidal thoughts is critical due to early risk. Morning dosing prevents insomnia. Drinking wine risks treatment failure or safety issues, critical in depression where stability is fragile. Further teaching must clarify this interaction, ensuring fluoxetine's efficacy and client well-being, making B the statement needing correction.

Correct Answer: A

Rationale: Nausea is one of the early manifestations of lithium toxicity. It is important to monitor for this symptom in patients taking lithium to detect toxicity early and prevent more serious complications. Hypotension and renal failure are more severe manifestations of lithium toxicity that occur at later stages. Muscle weakness is not typically associated with early lithium toxicity.

Correct Answer: D

Rationale: Heparin is an anticoagulant that enhances the activity of antithrombin III, a natural inhibitor of thrombin and factor Xa, to prevent clotting. The statement that it inhibits clotting by decreasing antithrombin III effects is false, as heparin actually potentiates antithrombin III, making this the incorrect option. Its oral bioavailability is negligible (not 20-30%), as it's a large polysaccharide requiring parenteral administration (e.g., IV or subcutaneous), so this is false. Heparin is highly plasma protein-bound, not low, contradicting that option. The correct statement, replaced in the fourth slot, is that heparin binds to antithrombin III, causing a conformational change that accelerates its anticoagulant effect. This mechanism is fundamental to its clinical use in thrombosis prevention, distinguishing it from oral anticoagulants like warfarin.

Correct Answer: C

Rationale: An agonist is a substance that binds to a receptor and triggers a biological response. By activating the receptor, an agonist mimics the action of the body's natural ligand that typically binds to the receptor. This activation may lead to a cascade of events within the cell, resulting in a specific physiological response. In contrast, antagonists block the receptor from being activated, while agonists work by binding to the receptor and initiating the desired response.