Tetracycline – Antibiotic: Uses & Effects

What is Tetracycline?

Tetracycline is an antibiotic belonging to the tetracycline class of drugs and is used to treat a wide variety of bacterial infections. It is classified as a broad-spectrum antibiotic, meaning it is effective against both gram-positive and gram-negative bacteria. Tetracycline was first discovered in the 1940s and remains one of the most widely used antibiotics worldwide.

Mechanism of Action

Tetracycline works by inhibiting bacterial protein synthesis. It penetrates the bacterial cell and reversibly binds to the 30S subunit of the bacterial ribosome. This prevents the attachment of aminoacyl-tRNA, effectively halting the production of essential proteins within the bacterial cell. Because human ribosomes have a different structure, tetracycline acts selectively against bacteria and does not typically harm human cells when used correctly.

Indications and Uses

Tetracycline is used for a wide range of infectious conditions. Common indications include:

• Respiratory tract infections (e.g., caused by Mycoplasma pneumoniae or Chlamydophila pneumoniae)
• Urinary tract infections
• Acne vulgaris (in combination with other treatments)
• Lyme disease (Borreliosis)
• Chlamydial infections
• Rickettsial infections
• Helicobacter pylori infections (as part of a combination therapy)
• Tropical diseases such as cholera and brucellosis

Dosage and Administration

Tetracycline is typically administered orally as tablets or capsules. The dosage depends on the type and severity of the infection, as well as the patient's body weight and kidney function. Standard adult dosages range from 250 to 500 mg, taken two to four times daily. It is important to take tetracycline on an empty stomach and to avoid taking it together with milk, dairy products, antacids, or iron supplements, as these can significantly reduce absorption of the active substance.

Side Effects

Like all medications, tetracycline can cause side effects. Common side effects include:

• Gastrointestinal complaints such as nausea, vomiting, and diarrhea
• Photosensitivity: increased sensitivity of the skin to sunlight (use of sunscreen is recommended)
• Tooth enamel damage and discoloration of teeth in children under 8 years of age
• Impairment of bone growth in infants and young children
• Dysbiosis: disruption of the natural gut flora
• In rare cases: increased intracranial pressure (pseudotumor cerebri)

Contraindications

Tetracycline must not be used in the following situations:

• Children under 8 years of age (risk of tooth and bone damage)
• Pregnant women (risk to both mother and child)
• Breastfeeding women
• Known hypersensitivity to tetracyclines
• Severe renal impairment (reduced elimination of the drug)

Antibiotic Resistance

Due to the frequent and sometimes inappropriate use of tetracyclines, many bacterial strains have developed resistance to this class of antibiotics. This means that tetracycline may no longer be effective against certain infections. To minimize the risk of resistance, tetracycline should only be taken on medical prescription and always for the full prescribed course of treatment.

References

1. World Health Organization (WHO) - Model List of Essential Medicines, 23rd Edition (2023). Available at: https://www.who.int/publications/i/item/WHO-MHP-HPS-EML-2023.02
2. Chambers, H. F. - Tetracyclines, Glycylcyclines, and Chloramphenicol. In: Brunton L. L. et al. (eds.), Goodman & Gilman's The Pharmacological Basis of Therapeutics, 13th Edition. McGraw-Hill Education, 2018.
3. European Medicines Agency (EMA) - Tetracycline: Summary of Product Characteristics. Available at: https://www.ema.europa.eu