All of the following interventions are correct when using the Z-track method of drug injection except:

Correct Answer: D

Rationale: When using the Z-track method of drug injection, it is important to prepare the injection site with alcohol to ensure cleanliness, use a needle that is at least 1" long to reach the muscle tissue, and aspirate for blood before injection to verify correct needle placement. However, rubbing the site vigorously after the injection is not recommended as it can cause medication to leak into subcutaneous tissue, compromising the medication's intended absorption and efficacy.

Correct Answer: D

Rationale: The correct answer is **D: 25G, 5/8" long** because insulin injections are typically administered subcutaneously (into the fatty tissue beneath the skin), and this needle size is optimal for such delivery. A 25G needle is thin enough to minimize discomfort while still allowing the viscous insulin solution to pass through smoothly. The 5/8" length is appropriate for most patients, including those with average subcutaneous fat thickness, as it ensures the medication is deposited in the correct tissue layer without risking intramuscular injection, which could alter absorption rates. This combination balances patient comfort with clinical efficacy, making it the standard for insulin administration. **Why the other options are incorrect:** - **A: 18G, 1 ½" long** – An 18G needle is excessively large for insulin injections. Such a thick gauge would cause significant pain and tissue trauma, and the 1 ½" length is unnecessarily long for subcutaneous injections, increasing the risk of intramuscular administration, which is undesirable for insulin due to faster absorption rates. This size is more suited for procedures like blood donation or IV access, not routine insulin delivery. - **B: 22G, 1" long** – While a 22G needle is thinner than an 18G, it is still thicker than the ideal for insulin. A 1" length may be suitable for some patients with thicker subcutaneous tissue, but it is unnecessarily long for most, increasing the risk of intramuscular injection. A shorter, finer needle (like 25G, 5/8") is preferred for routine use to ensure comfort and proper placement. - **C: 22G, 1 ½" long** – This option combines the drawbacks of both excessive gauge and excessive length. A 22G needle is too thick for comfortable insulin injections, and the 1 ½" length is far too long, almost guaranteeing intramuscular injection in many patients. Such a combination would lead to poor patient compliance due to pain and unpredictable insulin absorption kinetics. The key considerations for insulin needle selection are minimizing discomfort (favoring smaller gauges like 25G–31G) and ensuring subcutaneous deposition (favoring shorter lengths like 5/8" or 4mm for most patients). Option D aligns perfectly with these principles, whereas the other choices either compromise comfort, accuracy, or both.

Correct Answer: D

Rationale: The correct answer is **D: 26G** because intradermal injections require a fine, short needle to deposit medication or vaccines just below the epidermis without penetrating deeper tissues. A 26G needle is typically 26-gauge with a short bevel (usually ⅜ to ½ inch in length), which allows precise delivery into the dermal layer while minimizing trauma and leakage. The thin diameter reduces discomfort for the patient and ensures proper absorption, as intradermal injections rely on slow diffusion from the dermis into the local capillaries. This gauge is standard for procedures like tuberculin (TB) skin tests or allergy testing, where accuracy in placement is critical. **A: 20G** is incorrect because it is far too large for intradermal injections. A 20-gauge needle is thick and long, typically used for procedures requiring rapid fluid delivery (e.g., IV infusions or blood draws). Using such a large needle for intradermal injection would cause unnecessary pain, increase the risk of bleeding, and likely deposit the medication too deeply into subcutaneous or muscular tissue, compromising the intended immune response or diagnostic accuracy. **B: 22G** is incorrect because, while smaller than 20G, it is still too large for intradermal administration. A 22-gauge needle is commonly used for IM (intramuscular) injections or subcutaneous injections in adults, where deeper tissue penetration is needed. The diameter is too wide to reliably stay within the thin dermal layer, increasing the chance of misplaced medication and patient discomfort. **C: 25G** is incorrect because, although it is closer to the correct size, it is still less ideal than 26G for most intradermal procedures. While a 25-gauge needle can be used in some cases, it may not provide the same precision as a 26G needle, particularly for delicate applications like allergy testing where slight variations in depth can affect results. The marginally larger diameter may also cause more tissue disruption or leakage compared to the finer 26G needle. The choice of needle gauge balances precision, patient comfort, and clinical efficacy, and 26G is the optimal selection for intradermal injections due to its fine diameter and shallow penetration capability.

Correct Answer: A

Rationale: Parenteral administration refers to delivering medications via routes other than the digestive tract, typically involving injections. Penicillin, a widely used antibiotic, can be administered through specific parenteral routes to ensure optimal absorption, efficacy, and safety. The correct answer is **A (IM injection or an IV solution)** because penicillin formulations are specifically designed for intramuscular (IM) or intravenous (IV) administration. IM injections allow for slower absorption into the bloodstream, suitable for drugs like penicillin G benzathine, which provides prolonged action. IV administration delivers the drug directly into the bloodstream, ensuring rapid onset, which is critical in severe infections. Both methods are well-supported by pharmacokinetic studies and clinical practice guidelines. **Why other options are incorrect:** - **B (IV or intradermal injection):** Intradermal injections are used primarily for diagnostic tests (e.g., tuberculin skin tests) or vaccines, not for antibiotics like penicillin. The intradermal route lacks the capacity to deliver the volume or achieve the systemic drug levels required for antibiotic efficacy. - **C (Intradermal or subcutaneous injection):** Subcutaneous injections are unsuitable for penicillin because they can cause significant local irritation and inadequate absorption. Penicillin’s molecular properties and irritation potential make this route impractical, unlike drugs like insulin or heparin, which are designed for subcutaneous delivery. - **D (IM or subcutaneous injection):** While IM is correct, subcutaneous administration is inappropriate for penicillin due to the risk of tissue damage and inconsistent absorption. The subcutaneous layer lacks the vascularity needed for efficient drug distribution, leading to subtherapeutic levels and potential adverse reactions. The distinction between these routes hinges on the drug’s physicochemical properties, therapeutic goals, and anatomical considerations. Penicillin’s stability, solubility, and irritation profile limit its administration to IM or IV routes, ensuring both safety and clinical effectiveness. Misapplication via incorrect routes (e.g., intradermal or subcutaneous) could compromise treatment outcomes or cause harm, underscoring the importance of adhering to evidence-based administration practices.

Correct Answer: D

Rationale: The correct answer is D (600 mg) because 1 grain (gr) is equivalent to approximately 64.8 milligrams (mg). For practical clinical purposes, this is often rounded to 60 mg per grain for ease of calculation. Multiplying 10 gr by 60 mg/gr yields 600 mg. This conversion is standard in pharmacology, ensuring accurate dosing for medications like aspirin, where precision is critical. Choice A (0.6 mg) is incorrect because it represents a drastic underdose, likely resulting from a miscalculation where 10 gr was divided by 60 mg/gr instead of multiplied. This would be a 1000-fold error, rendering the dose therapeutically ineffective. Choice B (10 mg) is incorrect because it assumes a 1:1 conversion between grains and milligrams, which is not accurate. Grains are a much larger unit than milligrams, and this answer would also lead to a severe underdose, failing to achieve the intended therapeutic effect. Choice C (60 mg) is incorrect because it represents the conversion for 1 grain, not 10 grains. This error occurs if the physician's order is misinterpreted as a per-grain dose rather than the total required dose. While 60 mg might be a standard dose for certain aspirin formulations, it does not meet the 10 gr requirement specified in the question. Understanding unit conversions between grains and milligrams is crucial in medical practice to avoid dosing errors. Grains are an older unit still used in some prescriptions, whereas milligrams are the modern standard. Proper conversion ensures patient safety and therapeutic efficacy, particularly with medications like aspirin, where incorrect dosing can lead to treatment failure or toxicity. Always verify calculations and reference conversion tables when in doubt.