Which substance has the lowest rate of crossing renal tubular membranes and would therefore be excreted in the urine?

Correct Answer: C

Rationale: Ionized drugs cross renal tubular membranes poorly, staying in urine for excretion, unlike non-ionized or lipid-soluble drugs reabsorbed easily. Volatile drugs (e.g., anesthetics) excrete via lungs, not kidneys. Ionization traps drugs, a pharmacokinetic excretion key.

Correct Answer: B

Rationale: The nurse will discuss grapefruit juice when teaching a patient about possible drug-food interactions with antilipemic therapy. Grapefruit juice can inhibit the enzyme CYP3A4 in the liver, which can affect the metabolism of certain medications, including some antilipemic drugs. This interaction may lead to increased drug levels in the bloodstream, potentially causing harmful side effects. It is important for patients to be aware of this interaction and to consult their healthcare provider if they consume grapefruit juice while on antilipemic therapy.

Correct Answer: D

Rationale: Calcium regulates nerve transmission-e.g., neurotransmitter release, per physiology-not acid-base (HCO3-), glucose (insulin), or energy (ATP). Nerve function is key, per role.

Correct Answer: D

Rationale: Topiramate, a broad-spectrum antiepileptic, treats generalized tonic-clonic seizures by blocking sodium channels, enhancing GABA, and inhibiting glutamate, making it a first-line option per guidelines. Ethosuximide targets absence seizures. Felbamate, vigabatrin, and ezogabine have narrower uses or toxicity risks (e.g., aplastic anemia, vision loss), limiting them to refractory cases. Topiramate's efficacy, tolerability, and broad action suit primary generalized seizures, distinguishing it as a standard choice.

Correct Answer: D

Rationale: Midazolam is a short-acting benzodiazepine widely used as an anesthetic due to its rapid onset and potent sedative effects. Its mechanism involves enhancing the activity of gamma-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the brain, at GABA_A receptors—not GABA_B receptors, which are linked to different effects like muscle relaxation. By binding to a specific site on the GABA_A receptor, midazolam increases the frequency of chloride channel opening, leading to greater chloride ion conductance into neurons. This hyperpolarizes the neuron, making it less excitable and producing sedation, anxiolysis, and anesthesia. Dopamine enhancement is unrelated to its action, as is NMDA receptor blockade, which is a feature of drugs like ketamine. Partial agonism at serotonin (5HT) receptors also does not apply here. The facilitation of GABA-mediated chloride conductance is the precise mechanism that underpins midazolam's clinical utility as an anesthetic agent.