Tetracycline is a time-tested, broad-spectrum antibiotic belonging to the tetracycline class, widely utilized in clinical practice for its efficacy against a diverse range of gram-positive and gram-negative bacteria, as well as atypical pathogens. It functions by inhibiting bacterial protein synthesis at the ribosomal level, effectively halting microbial proliferation. This agent remains a cornerstone in treating various infectious diseases, from respiratory tract infections to sexually transmitted infections and zoonotic diseases, particularly in contexts where newer antibiotics are contraindicated or unavailable. Its well-documented pharmacokinetic profile and oral bioavailability make it a practical choice for both acute and chronic bacterial management under appropriate medical supervision.

Features

• Chemical class: Tetracycline antibiotic
• Mechanism: Binds to the 30S ribosomal subunit, inhibiting protein synthesis
• Spectrum: Broad-spectrum activity against aerobic and anaerobic bacteria, including Chlamydia, Rickettsia, Mycoplasma, and spirochetes
• Formulations: Available in 250 mg and 500 mg oral capsules; also as ointments and topical solutions
• Half-life: Approximately 6–11 hours, allowing for convenient dosing intervals
• Absorption: Best absorbed in a fasting state; significantly reduced by divalent cations (e.g., Ca²⁺, Mg²⁺, Fe²⁺)

Benefits

• Effectively treats a wide variety of bacterial infections, reducing the need for multiple antibiotics
• Oral formulation supports outpatient treatment and improves patient compliance
• Useful as an alternative for penicillin-allergic patients in certain indications
• Cost-effective compared to many newer broad-spectrum antibiotics
• Also employed in the management of inflammatory skin conditions like acne and rosacea due to anti-inflammatory properties at sub-antimicrobial doses

Common use

Tetracycline is indicated for the treatment of infections caused by susceptible organisms, including but not limited to:

• Respiratory tract infections (e.g., pneumonia, bronchitis)
• Sexually transmitted infections such as chlamydia, gonorrhea (as an alternative), and syphilis
• Skin and soft tissue infections, including acne vulgaris
• Rickettsial diseases (e.g., Rocky Mountain spotted fever, typhus)
• Zoonotic infections like brucellosis and tularemia
• Protozoal infections such as amebiasis (as an adjunct)

Dosage and direction

Dosage must be individualized based on infection severity, pathogen susceptibility, and patient factors.
Adults: Typical dose is 500 mg twice daily or 250 mg four times daily. For severe infections, an initial dose of 500 mg followed by 250 mg every 6 hours may be used.
Children above 8 years: 25–50 mg/kg/day divided into four equal doses.
Administration: Should be taken on an empty stomach, at least 1 hour before or 2 hours after meals, with a full glass of water to minimize esophageal irritation and ulceration. Do not take with dairy products, antacids, or iron supplements.
Duration: Treatment typically continues for at least 24–48 hours after symptoms subside, usually 7–14 days depending on infection type.

Precautions

• Use during tooth development (last trimester of pregnancy, infancy, childhood up to 8 years) may cause permanent discoloration of teeth and enamel hypoplasia.
• Avoid exposure to direct sunlight or UV light due to photosensitivity risk; use sunscreen and protective clothing.
• May cause false elevations in urinary catecholamines; inform laboratory personnel of tetracycline use.
• Use with caution in patients with renal impairment; dosage adjustment may be necessary.
• Prolonged use may result in fungal or bacterial superinfection, including pseudomembranous colitis.

Contraindications

• Hypersensitivity to tetracycline or any component of the formulation.
• Pregnancy and breastfeeding (except when no alternatives exist and benefit outweighs risk).
• Children under 8 years of age due to risk of tooth discoloration and bone growth inhibition.
• Severe hepatic dysfunction.

Possible side effect

Common side effects may include:

• Gastrointestinal disturbances (nausea, vomiting, diarrhea, epigastric distress)
• Photosensitivity reactions
• Glossitis, stomatitis, black hairy tongue
• Esophageal ulceration (if not taken with sufficient water)

Less common but serious side effects:

• Hepatotoxicity (especially with high doses or in pregnancy)
• Intracranial hypertension (pseudotumor cerebri)
• Blood dyscrasias (neutropenia, thrombocytopenia)
• Severe skin reactions such as Stevens-Johnson syndrome

Drug interaction

• Antacids, calcium, iron, magnesium, zinc supplements: Significantly reduce absorption.
• Oral contraceptives: Tetracycline may decrease efficacy; alternative contraception advised.
• Warfarin: May potentiate anticoagulant effect; monitor INR closely.
• Penicillins: Tetracycline may interfere with bactericidal activity of penicillins.
• Methoxyflurane: Concomitant use may cause fatal renal toxicity.
• Retinoids: Increased risk of pseudotumor cerebri.

Missed dose

If a dose is missed, take it as soon as remembered. If it is almost time for the next dose, skip the missed dose and resume the regular schedule. Do not double the dose to catch up.

Overdose

Symptoms may include nausea, vomiting, and diarrhea. In severe cases, pancreatitis and hepatotoxicity can occur. Management is supportive; dialysis is not effective due to high protein binding. Seek immediate medical attention.

Storage

Store at room temperature (15–30°C), in a tightly closed container, protected from light and moisture. Keep out of reach of children. Do not use after expiration date.

Disclaimer

This information is for educational purposes and does not replace professional medical advice. Tetracycline is a prescription medication and should only be used under the supervision of a qualified healthcare provider. Always follow the prescribed dosage and report any adverse effects promptly.

Reviews

“Tetracycline remains a reliable option for managing atypical pneumonia in adults. Its broad spectrum and oral bioavailability are advantageous in outpatient settings.” – Infectious Disease Specialist
“Effective for moderate to severe inflammatory acne, though gastrointestinal side effects can be limiting for some patients.” – Dermatologist
“Cost-effective and widely available, but requires careful patient education on administration and sun exposure.” – General Practitioner