Which of the following aminoglycosides is not available for parenteral use?
**Core Concept**
Aminoglycosides are a class of antibiotics that act by inhibiting bacterial protein synthesis. They are typically administered parenterally (intravenously or intramuscularly) due to their poor oral bioavailability.
**Why the Correct Answer is Right**
The correct answer is Tobramycin, which is primarily available for topical use, particularly in otic drops for the treatment of bacterial infections of the external auditory canal. It is not commonly used parenterally due to its limited indications and the availability of other aminoglycosides with broader therapeutic spectra.
**Why Each Wrong Option is Incorrect**
* **Option A:** Not applicable, as the question asks which aminoglycoside is not available for parenteral use.
* **Option B:** Gentamicin is a commonly used aminoglycoside for parenteral administration in the treatment of various bacterial infections.
* **Option C:** Amikacin is also a parenterally administered aminoglycoside used for the treatment of serious bacterial infections.
**Clinical Pearl / High-Yield Fact**
It's essential to note that aminoglycosides can cause nephrotoxicity and ototoxicity, particularly with prolonged use or high doses. Monitoring renal function and auditory function is crucial when administering these antibiotics.
**Correct Answer:** D. Tobramycin.