Pharmacokinetics and Pharmacodynamics — MCQs

A factor that is likely to increase the duration of action of a drug that is partially metabolized by CYP3A4 in the liver is:

Which of the following factors influences the duration of action of a drug?

A 70 kg man was given a drug with a dose of 100 mg/kg body weight, twice daily. The half-life (t1/2) is 10 hours, the plasma concentration is 1.9 mg/mL, and the clearance is unknown. What is the clearance of this drug?

All of the following statements regarding the bioavailability of a drug are true except which one?

Which of the following actions is NOT associated with tricyclic antidepressants?

With which of the following receptors does theophylline have an antagonistic interaction?

Find therapeutic index of drug from the information given below in the graph

A 34-year-old woman with bipolar I disorder has been maintained on lithium carbonate 900 mg/day for the past 18 months with good mood stabilisation. She presents to the outpatient clinic complaining of a worsening skin condition that began approximately 3 months after starting lithium. Her serum lithium level is 0.8 mEq/L (therapeutic range). She has no prior personal or family history of skin disease. Over the past 6 weeks, she has been using a moderate-potency topical corticosteroid prescribed by her dermatologist with no meaningful improvement; the eruption has continued to spread and now involves the face, scalp, and upper back, causing significant distress and social impairment. A dermatology referral photograph is shown (Image 1). Which of the following is the most appropriate next step in management?

A 35-year-old woman started on haloperidol for acute psychosis develops fever (102°F/38.9°C), severe muscle rigidity, altered mental status, and autonomic instability 3 days after medication initiation. Laboratory studies show creatine kinase of 15,000 U/L and white blood cell count of 16,000/mm³. Apply the most appropriate management approach.

Which antipsychotic has anti-suicidal properties?