It is a measure of drug activity in terms of the amount required to produce an effect.

Correct Answer: C

Rationale: Potency refers to the measure of drug activity in terms of the amount required to produce a particular effect. It is the strength or concentration of a drug that is needed to produce a specific effect. Potency is often expressed as the dose of a drug required to produce a certain response compared to a standard reference dose. It is an essential consideration in pharmacology as it helps determine the appropriate dosage needed for therapeutic effects and to avoid potential toxicity. Potency is distinct from efficacy, which is the ability of a drug to produce a desired effect regardless of the dose.

Correct Answer: C

Rationale: Tetracycline is a broad-spectrum antibiotic that can be rendered ineffective if taken with certain substances that interfere with its absorption. Dairy products, such as milk, contain calcium, which binds to tetracycline in the gastrointestinal tract, forming insoluble complexes that prevent the drug from being absorbed into the bloodstream. This interaction significantly reduces its therapeutic efficacy, making it crucial to instruct the client to avoid milk when taking the medication. Similarly, antacids (containing magnesium, aluminum, or calcium) and iron supplements also chelate tetracycline, decreasing its bioavailability, so choices A and B are incorrect and potentially harmful instructions. Reducing vitamin intake is unrelated to tetracycline's administration or efficacy, as vitamins do not typically interfere with its action unless specifically combined with minerals like iron or calcium. Therefore, the priority instruction is to avoid milk, ensuring the drug's effectiveness, which makes choice C the correct and most critical discharge teaching point.

Correct Answer: D

Rationale: Cocaine is not an ester type of local anesthetic. While procaine, amethocaine, benzocaine, and etidocaine are all ester type local anesthetics, cocaine belongs to the group of local anesthetics known as ester anesthetics. Even though cocaine has local anesthetic properties, it is specifically classified as a "amide type" local anesthetic, not an ester type. Therefore, the correct choice among the given options is D. Cocaine.

Correct Answer: C

Rationale: When administering IV potassium to a hypokalemic patient who is not on a heart monitor, it's important to ensure a controlled rate of infusion to prevent dangerous cardiac arrhythmias. The recommended maximum rate for IV potassium replacement in this scenario is typically no more than 20 mEq/hour. Faster administration rates can increase the risk of hyperkalemia and potentially lead to serious cardiac complications. Monitoring the patient closely for signs of hyperkalemia such as ECG changes or muscle weakness is also crucial during potassium replacement therapy.

Correct Answer: B

Rationale: Pentazocine, a mixed opioid agonist-antagonist, acts as a kappa receptor agonist and a partial mu receptor agonist, providing analgesia in opioid-naive patients. However, in a heroin addict with high mu receptor tolerance, pentazocine's partial antagonism at mu receptors can displace full agonists like heroin, precipitating withdrawal symptoms—sweating, restlessness, and heightened pain perception. Tolerance to pentazocine itself wouldn't typically increase pain; it would reduce efficacy. Pentazocine is an effective analgesic in appropriate contexts, so ineffectiveness isn't the issue. Incorrect dosing might alter efficacy or toxicity but wouldn't specifically cause this withdrawal-like reaction. The patient's history of heroin use explains this response, as pentazocine's antagonist properties disrupt the opioid equilibrium, unmasking withdrawal in a dependent individual.