**Question:** Saline diuresis is useful in toxicity of following drugs except?

A. Digitalis
B. Phenacetin
C. Diuretics
D. Calcium channel blockers

**Core Concept:**

Saline diuresis is a process that involves the administration of salt (sodium chloride) solutions to increase urine output, primarily by increasing the permeability of the renal tubules to water, which leads to dilute urine and increased urine volume. This is a therapeutic strategy used to manage various conditions associated with fluid overload, such as drug-induced nephrotoxicity or electrolyte imbalances.

**Why the Correct Answer is Right:**

In the context of drug toxicity, saline diuresis serves as a beneficial treatment in situations where excessive fluid retention is a concern, such as:

1. Digitalis toxicity: Digitalis is a cardiac glycoside that enhances the action of adenosine triphosphate (ATP) on the cardiac muscle. However, in toxicity, it causes increased cardiac contractility and heart rate, but also leads to increased renal blood flow and glomerular filtration rate, which can exacerbate fluid retention. Therefore, saline diuresis would not be effective or may even worsen the condition in digitalis toxicity.
2. Calcium channel blockers: Similar to digitalis, calcium channel blockers (e.g., verapamil) can also cause increased cardiac contractility and heart rate. However, unlike digitalis, calcium channel blockers may lead to vasodilation and hypotension, which can impair renal perfusion and compromise renal function. In this case, saline diuresis might not be beneficial.
3. Diuretics: Diuretics, such as furosemide, are specifically designed to stimulate renal tubules to increase urine production and promote diuresis. As a result, saline diuresis is unnecessary and potentially counterproductive when using diuretics.
4. Phenacetin: Phenacetin is an old analgesic and antipyretic drug that was associated with severe nephrotoxicity. In such cases, saline diuresis might be helpful to reduce renal toxicity.

**Why Each Wrong Option is Incorrect:**

5. **Option A (Digitalis):** As mentioned earlier, digitalis is a cardiac glycoside that increases cardiac contractility and heart rate, leading to fluid retention. Saline diuresis would not be effective or potentially worsen the condition in digitalis toxicity.
6. **Option B (Calcium channel blockers):** Calcium channel blockers can lead to vasodilation and hypotension, which compromises renal perfusion and function. Therefore, saline diuresis may not be helpful in calcium channel blocker toxicity.
7. **Option C (Diuretics):** Diuretics are designed to stimulate renal tubules, promoting diuresis, which negates the need for saline diuresis.
8. **Option D (Phenacetin):** While saline diuresis might be beneficial in treating nephrotoxicity caused by phenacetin use, it is an obsolete drug and should not be considered in current clinical practice.
9. **Option E (Calcium channel