Which one of the following is employed as antihistamine ?

Options

A. Chloramphenicol
B. Diphenylhydramine
C. Norothindrone
D. Omerprazole

Answer

To determine which of the following options is employed as an antihistamine, we need to analyze each option provided:

1. **Chloramphenicol**: This is a broad-spectrum antibiotic. It is used to treat infections caused by bacteria, such as cholera, pneumonia, and dysentery. It does not function as an antihistamine.

2. **Diphenylhydramine**: This is commonly known as Benadryl. It is used to treat allergic reactions, including symptoms such as hives, runny nose, itching, and other allergy-related symptoms. This compound works by blocking the action of histamine, making it an antihistamine.

3. **Northendrome**: This is an anti-fertility drug. It is not related to the treatment of allergies or the action of histamine.

4. **Omeprazole**: This is a proton pump inhibitor used to reduce stomach acid. It is not an antihistamine and is used for gastrointestinal issues, not allergies.

From the analysis above, the correct answer is **Diphenylhydramine**, as it is the only option that serves as an antihistamine.

### Step-by-Step Solution:
1. **Identify the options**: Look at the four given options: chloramphenicol, diphenylhydramine, northendrome, and omeprazole.

2. **Define antihistamine**: Understand that antihistamines are substances that block the action of histamine, which is involved in allergic reactions.

3. **Analyze each option**:
- **Chloramphenicol**: Recognize it as an antibiotic, not an antihistamine.
- **Diphenylhydramine**: Identify it as an antihistamine used for treating allergies.
- **Northendrome**: Understand it as an anti-fertility drug, not related to allergies.
- **Omeprazole**: Recognize it as a proton pump inhibitor for stomach acid, not an antihistamine.

4. **Select the correct answer**: Conclude that diphenylhydramine is the only option that is an antihistamine.