If you inject a drug with a pH of 6.5 and pka of 8.1 into a tissue with a pH of 7.4, to what extent would you expect this drug to be ionized in the tissue?

Correct Answer: A

Rationale: In pharmacology, understanding the concept of ionization of drugs is crucial for predicting their behavior in different body tissues. In this scenario, the drug with a pH of 6.5 and a pKa of 8.1 is a weak acid. When a weak acid is placed in a solution with a higher pH than its pKa, it tends to be more ionized because the environment is more basic than the drug itself. Therefore, when the drug is injected into tissue with a pH of 7.4 (higher than its pKa of 8.1), we can expect the drug to be predominantly in its ionized form. This is because in a basic environment, weak acids tend to ionize more readily. Option A, stating that the drug will be ionized over 50%, is correct as per the principles of acid-base chemistry and pharmacokinetics. Options B, C, and D are incorrect because in this scenario, the drug would not be 50% ionized, less than 50% ionized, or 100% ionized, respectively. Educationally, this question highlights the importance of understanding the relationship between the pH of a solution, the pKa of a drug, and its degree of ionization. It demonstrates how these factors influence drug behavior in different physiological environments, which is essential knowledge for pharmacists, nurses, and other healthcare professionals involved in medication administration.

Correct Answer: A

Rationale: This specificity allows the clinician to select a drug that will have the desired therapeutic effects without the undesired effects that occur when the entire sympathetic nervous system is blocked. In general, however, the specificity of adrenergic blocking agents depends on the concentration of drug in the body. Most specificity is lost with higher serum drug levels. The nurse should understand the importance of drug specificity to ensure safe and effective administration.

Correct Answer: D

Rationale: Enteric-coated tablets should not be crushed or opened, as this disrupts their protective coating and can cause gastric irritation. The patient should be instructed to swallow the tablets whole with plenty of water or milk. Crushing (A) or opening the tablets (C) is inappropriate. Notifying the healthcare provider (B) may be necessary if the patient cannot tolerate the medication.

Correct Answer: C

Rationale: Methotrexate is an immunosuppressant, increasing the risk of infections. Strict hand washing and infection prevention measures are crucial. Clay-colored stools are not normal and may indicate liver dysfunction. Pregnancy is contraindicated due to the risk of fetal harm. Sunlight exposure should be limited to reduce the risk of photosensitivity reactions.

Correct Answer: D

Rationale: Overdose toxicities differ in acid-base effects. Methanol causes metabolic acidosis via formic acid, not respiratory alkalosis. Lead poisoning leads to anemia or neurologic issues, rarely acid-base shifts. Paracetamol overdose induces lactic acidosis from liver failure, not respiratory changes initially. Salicylate (e.g., aspirin) overdose stimulates the respiratory center early, causing hyperventilation and respiratory alkalosis (low pCO2), but severe cases add metabolic acidosis (high anion gap) from uncoupled oxidative phosphorylation and lactic acid buildup. Codeine, an opioid, depresses respiration, causing acidosis, not alkalosis. Salicylate's dual pattern is distinctive, requiring urgent recognition—initial alkalosis shifts to acidosis as toxicity worsens, guiding bicarbonate or dialysis treatment.