Data Sheet
DOXINE
Doxycycline 100 mg Tablets
Presentation
DOXINE 100mg Tablets
Yellow film coated, biconvex tablets, 8.7 mm diameter, blank on both
sides.
Each tablet contains doxycycline hyclate equivalent to 100mg doxycycline.
Uses
Actions
Doxycycline is a broad spectrum antibiotic that is primarily bacteriostatic. It is thought to exert its antimicrobial effect by inhibition of protein synthesis. It prevents the binding of amino-acyl-tRNA to the messenger RNA-30S ribosomal subunit. The binding of fMet-tRNA is especially sensitive. As a result, initiation and therefore polyribosome formation, are blocked. Doxycycline inhibits only rapidly multiplying organisms.
Doxycycline is active against the following organisms:
- Rickettsiae: rocky mountain spotted fever, typhus fever and the typhus group, Q fever, rickettsial pox, and tick fevers.
- Mycoplasma pneumoniae.
- Agents of lymphogranuloma venereum and granuloma inguinale.
- The spirochetal agent of relapsing fever (Borrelia recurrentis).
- Chlamydia trachomatis.
- Haemophilus ducreyi (chancroid).
- Pasteurella pestis, and Pasteurella tularensis, Bartonella bacilliformis, Bacteroids species, Vibriocomma and Vibrio fetus and Brucella species (in conjunction with an aminoglycoside).
Doxycycline may be active against the following organisms although this should be confirmed by culture and sensitivity testing since many strains are resistant.
- Neisseria gonorrhoeae, Escherichia coli, Enterobacter aerogenes, Shigella species, Mima species and Herellea species, Haemophilis influenzae, Klebsiella species, Streptococcus species, Streptococcus pneumoniae, Staphylococcus aureus in respiratory, skin or soft tissue infection.
When penicillin is contraindicated, doxycycline is an alternative medicine in the treatment of infections due to:
- Treponema pallidum and Treponema pertenue (syphilus and yaws), Listeria monocytogenes, Clostridium species, Bacillus anthracis, Fusobacterium fusiforme (Vincent's infection), Actinomyces species.
Pharmacokinetics
Doxycycline is virtually completely absorbed after oral administration of tablets and the absorption is not notably influenced by the ingestion of food or milk. Peak serum levels of approximately 2.6 mcg/mL are achieved at 2 hours following a 200mg dose. Doxycycline diffuses readily into most body tissues, fluid and/or cavities and the volume of distribution has been measured as 0.7L/kg.
Plasma protein binding is variable. Doxycycline is concentrated by the liver in the bile. It is also excreted in the urine as the unchanged medicine in high concentration. The serum half-life of doxycycline ranges from 18-22 hours and this is not altered by severe renal failure, haemodialysis, age or hepatic failure.
Indications
Doxycycline is indicated in the treatment of uncomplicated chest, urethral, endocervical or rectal infections in adults caused by susceptible organisms (see Actions) as shown by culture and sensitivity testing. It may also be a useful adjunct to amoebicides in acute intestinal amoebiasis and has a place as adjunctive therapy in severe acne.
Dosage and Administration
The usual dose in adults is 200mg on the first day of treatment followed by a maintenance dose of 100mg/day. This may be given as either a single dose or divided doses administered every 12 hours.
In the management of more severe infections, 200mg daily should be given throughout the treatment period. Therapy should be continued at least 24-48 hours after symptoms and fever has subsided. If used in streptococcal infections, therapy should be continued for 10 days to prevent the development of rheumatic fever or glomerulonephritis.
For children over 12 years of age, the recommended dosage schedule for those under 50kg is 4 mg/kg on the first day and 2 mg/kg daily subsequently. For children over 50kg the usual adult dose is used.
In the treatment of acute gonococcal anterior urethreitus in males, administer either: 200mg stat and 100mg at bedtime on the first day followed by 100mg twice daily for 3-7 days, or 300mg stat followed by 300mg one hour later. For acute gonococcal infections in females use 200mg twice daily until cure is effected. When treating uncomplicated urethral, endocervical or rectal infection in adults caused by chlamydia trachomatis, give 100mg twice daily for at least 7 days. The treatment of primary or secondary syphilis requires 300mg daily in divided doses for at least 10 days.
In all cases doxycycline should be administered with adequate amounts of fluid or food and the patient should remain sitting or standing for up to 2 hours afterwards to prevent the possible development of oesophageal irritation.
Contraindications
- Hypersensitivity to doxycycline or any of the tetracyclines.
- It is contraindicated in children under the age of 12 years and in pregnancy.
Warnings and Precautions
The use of tetracyclines during tooth development (last half of pregnancy, infancy and in childhood to the age of 12 years) may cause permanent teeth discolouration. Enamel hypoplasia has also been reported. Doxycycline should not be used, therefore, unless other medicines are not available, are not likely to be effective, or are contraindicated.
As with other tetracyclines, doxycycline forms a stable calcium complex in any bone-forming tissue. A decrease in fibula growth rate has been observed in prematures given oral tetracycline. This reaction was shown to be reversible when the medicine was discontinued.
Photosensitivity manifested by an exaggerated sunburn reaction has been observed in some individuals taking tetracyclines. Treatment should be discontinued at the first evidence of skin erythema.
The use of doxycycline may occasionally result in over-growth of nonsusceptible organisms. If a resistant organism appears, the antibiotic should be discontinued and appropriate therapy instituted. In long term therapy, because tetracyclines have been shown to depress plasma prothrombin activity, patients who are on anti-coagulant therapy may require downward adjustment of their anti-coagulant dosage.
Use in Pregnancy
Results of animal studies indicate that tetracyclines cross the placenta, are found in foetal tissues and have toxic effects on the developing foetus manifested by retardation of skeletal development. The importance of this in humans is not known, however, doxycycline should not be used in pregnant women unless the benefit outweighs the risk.
Similarly, since doxycycline has been found in the milk of lactating women it should not be used in nursing mothers.
Carcinogenesis, Mutagenesis, Impairment of Fertility
Animal studies conducted in rats and mice have not provided conclusive evidence that tetracyclines may be carcinogenic or that they impair fertility.
In two mammalian cell lines, positive responses for mutagenicity occurred at concentrations of 60 and 10 mcg/mL respectively. In humans no association between tetracyclines and these effects have been made.
Adverse Effects
Gastrointestinal effects are common especially with high doses and are attributed to irritation of the mucosa. Such effects include anorexia, nausea, diarrhoea, glossitis, dysphagia, enterocolitis and inflammatory lesions (with monilial overgrowth) in the anogenital region.
Instances of oesophagitis and oesophageal ulceration have been reported. It appears that most of these patients took the medication immediately before going to bed.
Other reactions include: skin reactions such as maculopapular and erythematous rashes, exfoliative dermatitis, photosensitivity, hypersensitivity reactions such as urticaria, angioneurotic oedema, anaphylaxis, anaphylactoid purpura, pericarditis, and exacerbation of systemic lupus erythematosus, benign intracranial hypertension in adults disappearing on discontinuation of the medicine, haematologic abnormalities such as haemolytic anaemia, thrombocytopenia, neutropenia, and eosinophilia.
Interactions
Doxycycline may interfere with the bactericidal effect of penicillins and vice versa. Barbiturates and phenytoin may reduce the half-life of doxycycline. Administration of iron preparations may reduce the absorption of doxycycline after oral administration.
Overdosage
No reports of overdosage have been received. If such a case occurs, treatment requires discontinuation of the medicine and use of symptomatic treatment measures.
Pharmaceutical Precautions
Protect from light and moisture. Store below 25°C.
Medicine Classification
Prescription Medicine.
Package Quantities
DOXINE 100mg Tablet
Bottles of 250 tablets.
Further Information
Nil.
Name and Address
Mylan New Zealand Ltd
PO Box 11-183
Ellerslie
AUCKLAND
Telephone: 09-579-2792
Date of Preparation
2 February 2009