Tm

Uses

Acne vulgaris, Gluten enteropathy or sprue, Gnathostomiasis, Gonorrhoea, Superficial ophthalmic infections, Susceptible infections, Uncomplicated gonorrhoea

Tm is also used to associated treatment for these conditions: Localized Infection, Skin Infections, Superficial ocular infections, Susceptible bacteria

How Tm works

Tm inhibits cell growth by inhibiting translation. It binds to the 30S ribosomal subunit and prevents the amino-acyl tRNA from binding to the A site of the ribosome. The binding is reversible in nature. Tm is lipophilic and can easily pass through the cell membrane or passively diffuses through porin channels in the bacterial membrane.

Dosage

Tm dosage

Intramuscular:

Susceptible infections:

• Adult: 250 mg once daily or 300 mg daily in 2-3 divided doses.
• Child: >8 yr: 15-25 mg/kg (max 250 mg) daily in 2-3 divided doses.

Oral:

Susceptible infections:

• Adult: 250-500 mg 4 times daily. Max 4 g daily.
• Child: >8 yr: 25-50 mg/kg daily in 4 divided doses.

Acne:

• Adult: 250-500 mg bid.

Unco-mplicated gonorrhoea:

• Adult: 1.5 g initially, followed by 0.5 g four times daily up to a total of 9 g per treatment course.

Should be taken on an empty stomach. Take 1 hr before or 2 hr after meals.

Side Effects

Anorexia, nausea, vomiting,diarrhoea, glossitis, dysphagia, photosensitivity, oesphageal irritation and ulceration, nephrotoxicity, enterocolitis, rash (rare), blood dyscrasias. Headache, visual disturbances; intracranial hypertension; bulging fontanelles (infants).

Toxicity

Adverse effects may include stomach or bowel upsets and rarely allergic reactions. Very rarely severe headache and vision problems may be signs of dangerous intracranial hypertenion.

Precaution

Elderly, renal or hepatic impairment; myasthenia gravis; lupus erythematosus, children <12 yr.

Interaction

Antacids, iron, aluminum, calcium, magnesium, zinc salts reduce absorption. Concurrent use may cause increased levels of lithium, digoxin, halofantrine and theophylline; decreased concentrations of atovaquone. Increased risk of ergotism with ergot alkaloids. May cause failure of oral contraception

Food Interaction

• Avoid milk and dairy products. Take at least 1 hour before or two hours after consuming dairy products.
• Take separate from meals. Take at least one hour before or two hours after a meal.

[Moderate] ADJUST DOSING INTERVAL: Administration with food, particularly dairy products, significantly reduces tetracycline absorption.

The calcium content of these foods forms nonabsorbable chelates with tetracycline.

MANAGEMENT: Tetracycline should be administered one hour before or two hours after meals.

Tm multivitamins interaction

[Moderate] GENERALLY AVOID: The bioavailability of oral tetracyclines and iron salts may be significantly decreased during concurrent administration.

Therapeutic failure may result.

The proposed mechanism is chelation of tetracyclines by the iron cation, forming an insoluble complex that is poorly absorbed from the gastrointestinal tract.

In ten healthy volunteers, simultaneous oral administration of ferrous sulfate 200 mg and single doses of various tetracyclines (200 mg to 500 mg) resulted in reductions in the serum levels of methacycline and doxycycline by 80% to 90%, oxytetracycline by 50% to 60%, and tetracycline by 40% to 50%.

In another study, 300 mg of ferrous sulfate reduced the absorption of tetracycline by 81% and that of minocycline by 77%.

Conversely, the absorption of iron has been shown to be decreased by up to 78% in healthy subjects and up to 65% in patients with iron depletion when ferrous sulfate 250 mg was administered with tetracycline 500 mg.

Available data suggest that administration of iron 3 hours before or 2 hours after a tetracycline largely prevents the interaction with most tetracyclines except doxycycline.

Due to extensive enterohepatic cycling, iron binding may occur with doxycycline even when it is given parenterally.

It has also been shown that when iron is administered up to 11 hours after doxycycline, serum concentrations of doxycycline may still be reduced by 20% to 45%.

Coadministration of a tetracycline with any iron-containing product should be avoided if possible.

Otherwise, patients should be advised to stagger the times of administration by at least three to four hours, although separating the doses may not prevent the interaction with doxycycline.

Tm Drug Interaction

Moderate: charcoal, penicillin v potassiumUnknown: aspirin, amphetamine / dextroamphetamine, phentermine, hydroxyzine, Allergy , ciprofloxacin, loratadine, sulfamethoxazole / trimethoprim, fentanyl, cyclobenzaprine, atorvastatin, morphine, acetaminophen, famotidine, omeprazole, multivitamin, pyridoxine, cholecalciferol

Tm Disease Interaction

Major: colitisModerate: hemodialysis, hepatotoxicity, renal dysfunction, esophageal irritation

Elimination Route

Readily absorbed following oral administration.

Pregnancy & Breastfeeding use

Pregnancy Category D. There is positive evidence of human foetal risk, but the benefits from use in pregnant women may be acceptable despite the risk (e.g., if the drug is needed in a life-threatening situation or for a serious disease for which safer drugs cannot be used or are ineffective).

Contraindication

Hypersensitivity to tetracyclines, children <8 yr, renal damage. Pregnancy, lactation.

Special Warning

Renal Impairment-

• Intramuscular: Dosage may need to be reduced.
• Oral: Dosage may need to be reduced.

Innovators Monograph

You find simplified version here Tm