**Core Concept**
Alkalinization of urine is a pharmacological intervention used to treat certain types of poisoning by increasing the pH of the urine, which enhances the excretion of weakly acidic drugs or their metabolites. This technique is particularly useful for managing poisoning with salicylates, phenobarbital, and certain local anesthetics.

**Why the Correct Answer is Right**
The correct answer is **Barbiturates**. Alkalinization of urine increases the ionization of weakly acidic barbiturates, such as phenobarbital, making them less likely to be reabsorbed by the renal tubules. This enhances their excretion in the urine and reduces their toxicity. The mechanism involves the administration of sodium bicarbonate, which increases the pH of the urine, leading to the ionization of the barbiturate molecule and its increased excretion.

**Why Each Wrong Option is Incorrect**
**Option A:** **Salicylates** are indeed affected by alkalinization of urine, but they are not the primary reason for this intervention. While alkalinization can enhance the excretion of salicylates, it is not the most critical application of this technique.

**Option B:** **Local anesthetics** can be affected by alkalinization of urine, but this is not the primary reason for this intervention. Local anesthetics are more often managed with supportive care and specific antidotes.

**Option C:** **Tricyclic antidepressants** are not typically managed with alkalinization of urine. Their treatment involves supportive care, specific antidotes, and possibly hemodialysis.

**Clinical Pearl / High-Yield Fact**
Remember the "4 S"s of managing barbiturate poisoning: **Supportive care**, **Sodium bicarbonate** for alkalinization, **Sedation**, and **Supervision** in an intensive care unit setting.

**Correct Answer:** D.