DOXYCYCLINE-WGR

What it is

DOXYCYCLINE-WGR contains doxycycline hyclate equivalent to either 50 mg or 100 mg of doxycycline in film coated tablet form. Doxycycline is a broad-spectrum antibiotic synthetically derived from oxytetracycline. Doxycycline is primarily bacteriostatic and is active against a wide range of Gram-positive and Gram-negative organisms, exerting its antimicrobial effect by the inhibition of protein synthesis.

Approved indications

— Primary atypical pneumonia caused by Mycoplasma pneumoniae. — Queensland tick typhus, epidemic typhus fever, Q fever, murine endemic typhus fever, and Australo-Pacific endemic scrub typhus caused by Rickettsiae. — Psittacosis caused by Chlamydia psittaci. — Granuloma inguinale caused by Calymmatobacterium (Donovania) granulomatis. — Lymphogranuloma venereum, trachoma and inclusion conjunctivitis caused by Chlamydia trachomatis. — Cholera caused by Vibrio species. — Brucellosis caused by Brucella species (in conjunction with streptomycin). — Plague caused by Yersinia pestis. — Tularaemia caused by Francisella tularensis. — Bartonellosis caused by Bartonella bacilliformis. — Infections caused by Bacteroides species. — Chemoprophylaxis for malaria caused by Plasmodium falciparum in adults and children older than 10 years, and in combination with other antimalarial agents against malaria caused by Plasmodium vivax. — Syphilis caused by Treponema pallidum when penicillin is contraindicated. — Yaws caused by Treponema pertenue when penicillin is contraindicated. — Gonorrhoea caused by Neisseria gonorrhoeae when penicillin is contraindicated. — Acute intestinal amoebiasis as a useful adjunct to amoebicides. — Severe acne as adjunctive therapy.

Dosing overview

For adults and children over 8 years and above 50 kg in weight, the usual dose is 200 mg on the first day of treatment (100 mg every 12 hours) followed by a maintenance dose of 100 mg/day, administered as a single dose or as 50 mg every 12 hours. For more severe infections, particularly chronic infections of the urinary tract, 100 mg every 12 hours is recommended. For acute uncomplicated gonococcal infections, the dose is 100 mg twice daily for 5 to 7 days. For primary and secondary syphilis, the dose is 300 mg a day in divided doses for at least 10 days. For louse-borne typhus, treatment has been successful with a single oral dose of 100 mg or 200 mg according to severity, and for prevention of scrub typhus, 200 mg as a single dose. For severe acne, some efficacy has been demonstrated at a dose of 50 mg/day over a period of 12 weeks. For malaria chemoprophylaxis, the dose is 100 mg once daily commencing two days prior to entering malarious areas, while in the malarious area and for four weeks after leaving the malarious area, with a maximum of 100 mg daily for 8 weeks recommended. For children over 8 years of age and below 50 kg in weight without skeletal growth retardation, the adult dose of 100 mg should be recalculated on a weight basis of 2 mg/kg.

Key safety warnings

Photosensitivity manifested by an exaggerated sunburn reaction has been observed in some individuals taking tetracyclines. Patients taking tetracycline drugs should be advised against exposure to direct sunlight or ultra-violet light, and treatment should be discontinued at the first sign of skin erythema. Severe skin reactions, such as exfoliative dermatitis, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, and drug reaction with eosinophilia and systemic symptoms (DRESS) have been reported in patients receiving doxycycline. Fixed drug eruptions have occurred with doxycycline and have been associated with worsening severity upon subsequent administrations, including generalised bullous fixed drug eruption. If severe skin reactions occur, discontinue DOXYCYCLINE-WGR immediately and institute appropriate therapy. Intracranial hypertension (IH) has been associated with the use of tetracyclines including doxycycline. Women of childbearing age who are overweight or have a history of IH are at greater risk for developing tetracycline associated IH. Clinical manifestations include headache, blurred vision, diplopia and vision loss. Although intracranial hypertension typically resolves after discontinuation of treatment, the possibility for permanent visual loss exists. If visual disturbance occurs during treatment, prompt ophthalmologic evaluation is warranted. Clostridium difficile associated diarrhoea (CDAD) and antibiotic associated pseudomembranous colitis have been reported with doxycycline and may range in severity from mild diarrhoea to fatal colitis. CDAD must be considered in all patients who present with diarrhoea following antibiotic use. Careful medical history is necessary since CDAD has been reported to occur over two months after the administration of antibacterial agents. If doxycycline is ingested in an incorrect manner there is a risk of adhesion of the tablet to the oesophagus. If this happens, oesophageal injury may occur. Dysphagia, retrosternal pain, new or worsening heartburn are possible symptoms of such injury. In order to avoid oesophageal injury, doxycycline must be ingested with at least 100 mL of fluid (half a glass) and the patient must remain upright for at least 30 minutes.

Contraindications

Hypersensitivity to doxycycline, any of the excipients in DOXYCYCLINE-WGR or to any of the tetracyclines. Use in pregnancy (16 weeks post conception) and use in lactation are contraindicated. Rare cases of benign intracranial hypertension have been reported after tetracyclines and oral retinoids, such as isotretinoin or etretinate, and vitamin A. Concomitant treatment is therefore contraindicated. The concurrent use of tetracycline and methoxyflurane has been reported to result in fatal renal toxicity.

Regulatory history

DOXYCYCLINE-WGR was first listed on the Australian Register of Therapeutic Goods on 5 May 2020.