Which of the following can be used as local anesthetic agent for infiltration if a patient is allergic to amide and ester anaesthetic derivatives
**Core Concept**
Local anesthetics are classified into two main categories: amide and ester derivatives. Amide derivatives are more commonly used and have a lower risk of causing allergic reactions. Ester derivatives, on the other hand, are more likely to cause allergic reactions due to the presence of a para-aminobenzoic acid (PABA) moiety. In patients with a known allergy to both amide and ester derivatives, alternative local anesthetic agents must be considered.
**Why the Correct Answer is Right**
In such cases, benzocaine, a local anesthetic derived from benzoic acid, can be used as an alternative. Benzocaine is structurally distinct from both amide and ester derivatives and does not contain PABA, making it an ideal choice for patients with allergies to both categories.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is not specified which local anesthetic is being referred to, and many local anesthetics are derived from amide or ester compounds.
**Option B:** This option is incorrect because it is not a recognized local anesthetic agent for infiltration anesthesia.
**Option C:** This option is incorrect because it is not a suitable alternative for patients allergic to both amide and ester derivatives.
**Clinical Pearl / High-Yield Fact**
Benzocaine is a useful alternative local anesthetic agent in patients with allergies to both amide and ester derivatives, but it is essential to note that cross-reactivity can still occur, and a thorough allergy evaluation is necessary before its use.
**Correct Answer: D. Benzocaine**