TETRACYCLINE

Posology Tetracycline should be given one hour before or two hours after meals, since food and some dairy products interfere with absorption. The tablets should be taken with a good drink of water. Therapy should be continued for up to three days after symptoms have subsided.

All infections due to Group A beta-haemolytic streptococci should be treated for at least 10 days.

Adults (including the elderly) and children over 12 years:

The minimum recommended dosage is 250mg every six hours. Therapeutic levels are attained more rapidly by the administration of 500mg initially, followed by 250mg every six hours. For severe infections, the dosage may be increased to 500mg every six hours.

Children under 12 years:

Contraindicated in this age group.

Elderly:

Usual adult dose. Caution should be observed as subclinical renal insufficiency may lead to drug accumulation.

Renal impairment:

In general tetracyclines are contraindicated in renal impairment and the dosing recommendations only apply if use of this class of drug is deemed absolutely essential. Total dosage should be decreased by reduction of recommended individual doses and/or by extending time intervals between doses.

Dosage recommendations in specific infections:

Skin infections: 250-500mg daily in single or divided doses should be administered for at least three months in the treatment of acne vulgaris and severe rosacea.

Streptococcal infections:

A therapeutic dose of tetracycline should be administered for at least 10 days. Brucellosis: 500mg tetracycline four times daily accompanied by streptomycin. Sexually transmitted diseases: 500mg four times daily for seven days is recommended in the following infections: Uncomplicated gonococcal infections (except anorectal infections in man); uncomplicated urethral, endocervical or rectal infection caused by Chlamydia trachomatis; non- gonococcal urethritis caused by Ureaplasma urealyticum.

The following convention has been utilised for the classification of frequency. Very common (≥ 1/10); common( ≥ 1/100 to < 1/10); uncommon (≥ 1/1000 to < 1/100); rare (≥ 1/10,000 to < 1/1000); very rare (< 1/10,000); Not known (frequency cannot be estimated from the available data).

4) Blood and lymphatic system disorders: Rare: haemolytic anaemia, thrombocytopenia, neutropenia, eosinophilia, agranulocytosis, aplastic anaemia. 8), fixed drug eruptions, exfoliative dermatitis.

Endocrine disorders:

Not known: brown-black microscopic discolouration of thyroid tissue. No abnormalities of thyroid function are known to occur.

Nervous system disorders:

Not known: headache.

Eye disorders:

Not known: visual disturbances, permanent visual loss. 3). Presenting features were headache, dizziness, tinnitus and visual disturbances including blurring of vision, scotomata and diplopia. Permanent visual loss has been reported. Treatment should cease if evidence of raised intracranial pressure develops.

6). Tooth discolouration has also been seen in adults. If gastric irritation occurs, tablets should be taken with food.

Hepatobiliary disorders:

Rare: transient increases in liver function tests, hepatitis, jaundice, hepatic failure. Not known: hepatotoxicity associated with fatty liver.

Skin and subcutaneous tissue disorders:

Not known: erythematous and maculo-papular rashes, photosensitivity (Patients exposed to direct sunlight or ultraviolet light should be advised to discontinue treatment if any skin reaction occurs), pruritis, bullous dermatoses, skin discolouration.

Tetracyclines depress plasma prothrombin activity; therefore reduced dosages of concurrent anticoagulants may be required. 8). Enamel hypoplasia has also been reported. This adverse reaction is more common during long-term use of the drug but has been observed following repeated short-term courses.

• The anti-anabolic action of tetracyclines may cause an increase in BUN. While this is not a problem in those with normal renal function, in patients with significantly impaired renal function, higher serum levels of tetracycline may lead to azotaemia, hyperphosphataemia and acidosis.

• When treating venereal disease, where co-existent syphilis is suspected, proper diagnostic procedures should be utilised. In all such cases, monthly serological tests should be made for at least four months. 8). Constant observation of the patients is essential.

If a resistant organism appears, the antibiotic should be discontinued and appropriate therapy instituted. • Diarrhoea, particularly if severe, persistent and/or bloody, during or after treatment (including several weeks after treatment) with Tetracycline tablets, may be symptomatic of Clostridium difficile- associated disease (CDAD).

8). It is therefore important to consider this diagnosis in patients who develop serious diarrhoea during or after treatment with Tetracycline tablets. If CDAD is suspected or confirmed Tetracycline tablets should be stopped immediately and appropriate therapy initiated without delay.

Anti-peristaltic drugs are contraindicated in this clinical situation. • In longterm therapy, periodic laboratory evaluation of organ systems, including haematopoietic, renal and hepatic studies should be performed. • High doses of tetracyclines have been associated with a syndrome involving fatty liver degeneration and pancreatitis.

• The use of tetracycline in general is contraindicated in renal impairment due to excessive systemic accumulation. They should not be used with penicillins and they should not be discontinued if supra-infection occurs. Tetracyclines should also be used with caution in patients with hepatic impairment or those receiving drugs which may have hepatotoxic effects; high doses should be avoided.

1. 8); - Pregnancy and breastfeeding women. 8).