Elimination rate constant (Kelim) is defined by the following parameter:

Correct Answer: D

Rationale: The elimination rate constant (Kelim) is a key parameter that quantifies the rate at which a drug is removed from the body. It is directly related to the drug's half-life (t ½). The correct answer is D because the half-life is the time required for the drug concentration to decrease by half in the body, which is a crucial factor in determining the rate of elimination. Rate of absorption (A) refers to the speed at which a drug enters the bloodstream, not its elimination. Maximal concentration in plasma (B) and highest single dose (C) are not directly related to the elimination rate constant, making them incorrect choices.

Correct Answer: D

Rationale: The correct answer is D because Bethanechol is a muscarinic agonist, meaning it specifically targets muscarinic receptors, not nicotinic receptors. Nicotinic receptors are primarily found at neuromuscular junctions and act on skeletal muscle. Bethanechol's main action is on smooth muscle, particularly in the gastrointestinal and urinary tracts. It is used to stimulate bladder contractions in cases of urinary retention and to treat abdominal distention. Choice A is incorrect because bethanechol is not resistant to hydrolysis, and choice B is incorrect because it is purely muscarinic in action, not exerting nicotinic effects.

Correct Answer: B

Rationale: The correct answer is B: Glaucoma. Antimuscarinics are not used in the treatment of glaucoma because they can increase intraocular pressure, worsening the condition. Motion sickness, hyperhidrosis, and asthma can all be treated with antimuscarinics due to their ability to block the action of acetylcholine at muscarinic receptors, thereby reducing symptoms associated with these disorders. It is important to remember that antimuscarinics can have various effects on different organ systems based on the receptors they block, so their use must be carefully tailored to the specific condition being treated.

Correct Answer: B

Rationale: The correct answer is B: Terbutaline. Terbutaline is a selective beta-2 adrenergic agonist that causes bronchodilation by acting on beta-2 receptors in the lungs without significant cardiac stimulation. Isoprenaline (A) is a non-selective beta agonist that can cause significant cardiac stimulation. Xylometazoline (C) is a nasal decongestant that acts on alpha-adrenergic receptors and does not cause bronchodilation. Methoxamine (D) is an alpha-1 adrenergic agonist that can actually cause bronchoconstriction and does not cause bronchodilation.

Correct Answer: A

Rationale: Rationale: A: Adrenoreceptor antagonists work by reversible or irreversible interaction with adrenoreceptors, blocking the action of catecholamines. This directly affects the sympathetic nervous system. B: Depletion of catecholamines is not the primary mechanism of action of adrenoreceptor antagonists. C: Blockade of amine reuptake pumps is not the primary mechanism of action of adrenoreceptor antagonists. D: Nonselective MAO inhibition is not the mechanism of action of adrenoreceptor antagonists.