Diphenylhydrazine and terfenadine are ______ drugs

Answer

To answer the question "Diphenylhydrazine and terfenadine are ______ drugs," we need to identify the classification of these two compounds.

### Step-by-Step Solution:

1. **Identify the Compounds**: The question mentions two compounds: diphenylhydrazine and terfenadine.

2. **Research the Compounds**:
- **Diphenylhydrazine** is known to be a compound that has been used in the treatment of allergies.
- **Terfenadine** is an antihistamine that was used to treat allergic conditions.

3. **Understand the Function**: Both compounds are involved in the management of allergic symptoms. They work by blocking the action of histamine, a substance in the body that causes allergic symptoms.

4. **Classify the Drugs**: Since both diphenylhydrazine and terfenadine are used to alleviate allergic reactions by blocking histamine, they fall under the category of **antihistamines**.

5. **Final Answer**: Therefore, the correct answer to the question is: "Diphenylhydrazine and terfenadine are **antihistamine** drugs."