Doxycycline Hydrochloride is indicated in the following infections caused by susceptible microorganisms:

• Respiratory tract infections: Pneumonia, influenza, sinusitis, bronchitis, tonsillitis, tracheitis.

• Gastrointestinal tract infections: Cholera, traveler's diarrhea, shigella dysentery, acute intestinal amebiasis.

• Chlamydial infections: Lymphogranuloma venereum, psittacosis, trachoma.

• Sexually transmitted diseases: Non-gonococcal urethritis, acute pelvic inflammatory disease, uncomplicated urethral and endocervical or rectal infections, gonorrhea, syphilis, pyelonephritis, cystitis.

• Other infections: Impetigo, furunculosis, inclusion conjunctivitis, brucellosis, tularemia, cellulitis, acne, and Q-fever.

Doxycycline is a highly active broad-spectrum antibiotic of the tetracycline group. It is effective against a wide range of Gram-positive and Gram-negative bacteria, spirochetes, mycoplasma, rickettsia, and mycobacteria. Doxycycline is used as an alternative to penicillin in the treatment of gonorrhea and syphilis. Doxycycline has its main mechanism of action on protein synthesis. Inside the bacterial cell, it inhibits protein synthesis.

Doxycycline Hydrochloride is a semisynthetic tetracycline antibiotic with broad-spectrum activity. It is primarily a bacteriostatic antibiotic. It has a similar spectrum of activity to other tetracyclines but, in particular, is more active against Staphylococcus aureus and Nocardia. The drug is often active against penicillin-resistant strains of Staphylococcus aureus and against strains of those organisms that are resistant to other tetracyclines. Certain Gram-negative strains of E. coli, Proteus mirabilis, and Klebsiella, which are often resistant to tetracycline, may be sensitive to doxycycline. In addition, 70–90% of the various anaerobes are sensitive to doxycycline, and Bacteroides fragilis is more likely to be sensitive to doxycycline than to other tetracyclines.

Doxycycline is active against most strains of Haemophilus influenzae and is particularly useful for infections with H. ducreyi, Actinomyces, Brucella, and Vibrio cholerae. It is also active against Nocardia, Chlamydia, Mycoplasma, and a wide range of Rickettsiae. Doxycycline is active against spirochetes such as Borrelia recurrentis, Treponema pallidum, and Treponema pertenue. It is also active against Plasmodium falciparum.

Usual dose: 200 mg on the first day, then 100 mg daily for 7–10 days.

Severe infections (including refractory urinary tract infections): 200 mg daily for 10 days.

Acne: 100 mg daily.

Uncomplicated genital chlamydia, non-gonococcal urethritis: 100 mg twice daily for 7–21 days (14–21 days in pelvic inflammatory disease).

Administration

Capsules should be swallowed whole with plenty of fluid during meals while sitting or standing.

Absorption of tetracyclines is impaired by antacids containing aluminium, calcium, or magnesium, and iron-containing preparations. Absorption of tetracyclines is also impaired by bismuth salicylate. Barbiturates, carbamazepine and phenytoin decrease the half-life of doxycycline. Concurrent use of tetracyclines may render oral contraceptives less effective. Patients who are on anticoagulant therapy may require downward adjustment of their anticoagulant dosages. It is advisable to avoid giving tetracyclines in conjunction with penicillin.

Doxycycline is contraindicated in patients who have shown hypersensitivity to any of the tetracyclines. Doxycycline is contraindicated in children under 8 years of age. It is also contraindicated in pregnant women and in lactating mothers.

Nausea, vomiting, diarrhoea, skin rashes, haemolytic anaemia, and eosinophilia may be reported.

Doxycycline should be avoided in pregnant women because of the risk of both staining and effect on bone growth in the foetus. Doxycyclines enter breast milk, and mothers taking these drugs should not breastfeed their child.

The use of drugs of the tetracycline class during tooth development (last half of pregnancy, infancy, and childhood up to the age of 8 years) may cause permanent discoloration of teeth. Tetracycline drugs, therefore, should not be used in this age group.

Tetracycline group of drugs

Keep all medicines out of reach of children. Store in a cool and dry place, protected from light.