Which of the following drug is an antibiotic?

Chloramphenicol

The correct answer is option 3. Chloramphenicol.

Antibiotics are a class of drugs specifically designed to kill or inhibit the growth of bacteria. They are used to treat bacterial infections in the body. Antibiotics work by targeting specific components of bacterial cells, such as cell walls, protein synthesis, DNA replication, or metabolic pathways. Importantly, antibiotics are not effective against viral infections.

Detailed Analysis of Each Option:

1. Morphine

Classification: Opioid Analgesic

Mechanism of Action: Morphine is a powerful pain reliever that works by binding to opioid receptors in the brain and spinal cord. This binding alters the perception of pain and emotional response to pain.

Use: Morphine is primarily used to manage severe acute or chronic pain, such as pain from surgery, injury, or cancer.

Not an Antibiotic: Morphine does not affect bacteria and does not have any antimicrobial properties.

2. Equanil (Meprobamate)

Classification: Tranquilizer/Anxiolytic

Mechanism of Action: Equanil (Meprobamate) is used as a tranquilizer to treat anxiety disorders. It works by depressing activity in the central nervous system (CNS), producing a calming effect.

Use: Equanil is prescribed for managing short-term anxiety, tension, and nervousness.

Not an Antibiotic: Equanil does not have any antibacterial properties and is not used to treat infections.

3. Chloramphenicol

Classification: Antibiotic

Mechanism of Action: Chloramphenicol is a broad-spectrum antibiotic that works by inhibiting bacterial protein synthesis. Specifically, it binds to the 50S ribosomal subunit of bacteria, preventing the formation of peptide bonds during protein synthesis. This action effectively halts bacterial growth and replication.

Use: Chloramphenicol is used to treat a wide range of bacterial infections, including those caused by Gram-positive and Gram-negative bacteria. It is particularly used in serious infections like typhoid fever, bacterial meningitis, and infections caused by anaerobic bacteria.

Antibiotic: Chloramphenicol is specifically designed to target bacterial cells, making it effective against bacterial infections.

4. Valium (Diazepam)

Classification: Benzodiazepine

Mechanism of Action: Valium (Diazepam) is a medication that enhances the effect of the neurotransmitter gamma-aminobutyric acid (GABA) in the brain. This results in sedative, anxiolytic (anti-anxiety), muscle relaxant, and anticonvulsant effects.

Use: Valium is used to treat conditions such as anxiety disorders, muscle spasms, alcohol withdrawal symptoms, and seizures.

Not an Antibiotic: Valium does not target bacteria and has no role in treating bacterial infections.

Summary:

Chloramphenicol is the only drug in the list that is classified as an antibiotic. It works by inhibiting bacterial protein synthesis and is used to treat bacterial infections. The other drugs—Morphine, Equanil, and Valium—have entirely different therapeutic roles. Morphine is a pain reliever, Equanil is used to treat anxiety, and Valium is used for anxiety, muscle spasms, and seizures. None of these drugs have antimicrobial properties or are used to treat infections.

Thus, Chloramphenicol is the correct answer as it is an antibiotic designed to combat bacterial infections.