Doxycycline – A Broad-Spectrum Antibiotic with Diverse Clinical Uses

 

Discover the complete medical profile of Doxycycline, a broad-spectrum tetracycline antibiotic. Learn about its mechanism of action, indications, dosage, side effects, brand names, and price in this comprehensive guide.

Table of Contents:

1. Introduction  

2. Mechanism of Action  

3. Pharmacokinetics and Pharmacodynamics  

4. Indications  

5. Drug of Choice  

6. Contraindications  

7. Side Effects  

8. Drug Interactions  

9. Dosage  

10. Brand Names and Price  

11. Conclusion

1. Introduction:

Doxycycline is a long-acting tetracycline antibiotic used to treat a wide variety of bacterial infections, including respiratory, urinary, and sexually transmitted infections. It is also used for acne and as prophylaxis against malaria.

2. Mechanism of Action:

Doxycycline inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit, preventing the addition of amino acids to growing peptide chains. It is bacteriostatic in nature.

3. Pharmacokinetics and Pharmacodynamics:

- *Bioavailability:* ~90–100% (oral)  

- *Half-life:* ~18–22 hours  

- *Protein binding:* 80–90%  

- *Metabolism:* Minimal hepatic metabolism  

- *Excretion:* Primarily in feces and urine  

- *Onset of action:* 2–4 hours (oral)

4. Indications:

- Respiratory tract infections (pneumonia, bronchitis)  

- Acne vulgaris  

- Chlamydia and gonorrhea  

- Malaria prophylaxis  

- Rickettsial infections (e.g., Rocky Mountain spotted fever)  

- Lyme disease  

- Anthrax (including post-exposure prophylaxis)  

- Periodontitis

5. Drug of Choice: 

Doxycycline is the drug of choice for:  

- Rickettsial infections  

- Lyme disease (early stages)  

- Malaria prophylaxis  

- Acne in adolescents and adults  

- Chlamydia infections

6. Contraindications:

- Hypersensitivity to tetracyclines  

- Pregnancy (especially 2nd and 3rd trimesters)  

- Children under 8 years (risk of teeth discoloration)  

- Severe hepatic impairment (use with caution)

7. Side Effects:

 

- Gastrointestinal upset (nausea, vomiting, diarrhea)

- Photosensitivity  

- Esophageal irritation  

- Tooth discoloration (in children)  

- Superinfections (e.g., candidiasis)  

- Rare: Intracranial hypertension

8. Drug Interactions:

- *Antacids/calcium/iron:* Decrease absorption  

- *Oral contraceptives:* Reduced efficacy  

- *Warfarin:* Enhanced anticoagulant effect  

- *Penicillin:* Antagonistic effect when used together

9. Dosage:

Adults (oral):

  - Initial: 100 mg twice on day 1  

  - Maintenance: 100 mg once daily or 50 mg twice daily  

Malaria prophylaxis:

100 mg daily, starting 1–2 days before travel and continued for 4 weeks after

10. Brand Names and Price:

Brand Names:

Doryx®️

Vibramycin®️

Doxy-1®️

Doxicip®️

Monodox®️  

Vibramycin

Price:

  - Tablets (100 mg, 10–20 tablets): 8–40 depending on brand and region  

  - Capsules also available in similar dosage forms

11. Conclusion:

Doxycycline remains a versatile and widely used antibiotic due to its broad-spectrum efficacy, high oral bioavailability, and affordability. From infectious diseases to acne treatment and malaria prevention, its clinical utility is vast. However, appropriate dosing and monitoring for side effects are essential, especially in long-term use.