DOXYCOTEC 100MG CAPSULES

Indications

• Acne vulgaris
• Chlamydia infections
• Community-acquired pneumonia
• Cholera
• Gonorrhea
• Malaria prophylaxis
• Respiratory tract infections
• Urinary tract infections
• Rickettsial infections
• Periodontal disease

Dosage

Children: Refer to the BNF for Children for appropriate dosing guidelines in paediatric patients.

Adults: Refer to the BNF for specific dosing recommendations based on the indication being treated.

Mechanism of action

Doxycycline exerts its antibacterial effect by inhibiting protein synthesis in bacteria. It binds reversibly to the 30S ribosomal subunit, preventing the attachment of aminoacyl-tRNA to the mRNA-ribosome complex, which halts the translation process and ultimately inhibits bacterial growth. This mechanism makes it effective against a variety of microorganisms, including those that are resistant to other antibiotics.

Pharmacodynamics

Doxycycline displays bacteriostatic activity, meaning it inhibits the growth and reproduction of bacteria rather than killing them outright. The drug has a long half-life, allowing for once or twice daily dosing in most cases. Resistance to doxycycline can occur through various mechanisms, including efflux pump activation and ribosomal protection, which may reduce its effectiveness over time.

Pharmacokinetics

Doxycycline is well-absorbed from the gastrointestinal tract, with bioavailability ranging from 90% to 100%. It is distributed widely throughout the body, including penetration into tissues and fluids, such as lung tissue and pleural fluid. The drug is primarily excreted unchanged in the urine, with a half-life of approximately 18 to 22 hours in healthy adults. Adjustments may be necessary in patients with renal impairment, although significant dose modifications are generally not required for patients with mild to moderate renal dysfunction.

Contra-indications

• Hypersensitivity to doxycycline or any of the tetracycline antibiotics
• Severe hepatic impairment
• Pregnancy (especially during the second and third trimesters)
• Children under 8 years of age due to the risk of teeth discoloration

Adverse effects

• Gastrointestinal disturbances (nausea, vomiting, diarrhea)
• Photosensitivity
• Esophageal irritation or ulceration
• Allergic reactions (rash, urticaria)
• Hepatotoxicity
• Intracranial hypertension

Interactions

• Antacids containing aluminum, calcium, or magnesium can reduce absorption
• Iron supplements may interfere with absorption
• Warfarin and other anticoagulants may have increased effects
• Hormonal contraceptives may be less effective

Precautions

• Use with caution in patients with renal impairment
• Monitor for signs of hepatotoxicity
• Consider the potential for photosensitivity and advise patients to avoid excessive sun exposure
• Assess for any history of esophageal disorders

Pregnancy

Doxycycline is generally contraindicated during pregnancy due to the risk of teratogenic effects and potential impact on fetal bone development.

Breast-feeding

Doxycycline is excreted in breast milk and may affect the nursing infant. Caution is advised, and its use should be limited unless deemed necessary.

Storage

Store at room temperature, away from moisture and heat. Protect from light.

Formulations

• Capsules
• Tablets
• Oral suspension
• Injectable solution