Characteristic unwanted reaction which isn’t related to a dose or to a pharmacodynamic property of a drug is called:

Correct Answer: A

Rationale: The correct answer is A: Idiosyncrasy. Idiosyncrasy refers to a unique and unpredictable reaction to a drug that is not related to the dose or pharmacodynamic properties. This type of reaction can vary greatly among individuals and is not based on common drug responses. B: Hypersensitivity involves an exaggerated immune response to a drug and is dose-dependent. C: Tolerance is the decreased response to a drug over time with repeated use, not an unrelated reaction. D: Teratogenic action refers to drugs causing harm to a developing fetus, not an unrelated reaction in the patient.

Correct Answer: C

Rationale: The correct answer is C: Pirenzepine. Pirenzepine is a selective M1 blocker because it specifically targets the M1 subtype of muscarinic receptors. This selectivity reduces the likelihood of off-target effects associated with non-selective antimuscarinic drugs. Atropine (choice A) and Scopolamine (choice B) are non-selective antimuscarinic drugs, affecting multiple muscarinic receptor subtypes. Homatropine (choice D) is a non-selective antimuscarinic drug primarily used for its mydriatic effect in ophthalmology. Therefore, the correct choice is C as it is the only drug that selectively blocks the M1 receptor subtype.

Correct Answer: C

Rationale: The correct answer is C: Beta1 receptor. Stimulation of Beta1 receptors in the heart leads to increased heart rate, contractility, and conduction velocity. This is crucial for the direct effects on the heart. Alpha1 receptors (choice A) primarily cause vasoconstriction, not direct effects on the heart. Alpha2 receptors (choice B) inhibit norepinephrine release and have minimal effects on the heart. Beta2 receptors (choice D) are mainly found in the lungs and blood vessels, leading to bronchodilation and vasodilation, rather than direct effects on the heart.

Correct Answer: A

Rationale: The correct answer is A: Drug-induced parkinsonism. Sympathomimetics stimulate the sympathetic nervous system, which can lead to adverse effects like cerebral hemorrhage, pulmonary edema, myocardial infarction, and ventricular arrhythmias due to increased heart rate and blood pressure. However, they do not cause drug-induced parkinsonism, which is associated with medications that affect dopamine levels in the brain. Therefore, choice A is the correct answer. Choices B, C, and D are incorrect because sympathomimetics can indeed lead to these adverse effects due to their actions on the sympathetic nervous system.

Correct Answer: C

Rationale: The correct answer is C because hypnotic drugs are primarily used to induce drowsiness and promote sleep. They help with insomnia and encourage the onset and maintenance of sleep. This is achieved by affecting the brain's neurotransmitters and promoting relaxation. Options A and D are incorrect as hypnotic drugs are not intended to specifically reduce anxiety, exert a calming effect, or prevent mood swings in patients with bipolar affective disorders. Option B is incorrect as hypnotic drugs do not induce an absence of sensation; that would be more characteristic of anesthetics.