Doxycycline dosage

The interaction between doxycycline and rifampicin is established and of clinical importance. Monitor the effects of concurrent use and increase the doxycycline dosage as necessary. No clinically important adverse interaction appears to occur between doxycycline and streptomycin. 

Oral tetracyclines that probably act as anti-inflammatory and marked immunodepressing agents. Dosages currently used are 250 mg twice daily for oxytetracycline 100 mg twice daily for minocycline 100 mg once daily for doxycycline and 400 mg for lymecycline. Therapy should be prolonged for 20 days [9]... 

A further example of the ability of doxycycline to penetrate into secretions is provided by a report [53] of a comparative trial of the drug and ampicillin in acute exacerbations in chronic bronchitis. It was found that 100 mg doxycycline daily and ampicillin 250 mg four times daily were clinically equally effective. Bacterio-logically, however, it was found that H. influenzae re-appeared in sputum more often during ampicillin therapy than y ith doxycycline. This was attributed, following earlier workers, to the failure of ampicillin (in the dose used) to reach adequate levels in sputum. By inference, therefore, doxycycline (at one tenth of the daily dosage) achieves adequate levels more readily. 

Tetracyclines are excreted mainly in bile and urine. Concentrations in bile exceed those in serum tenfold. Some of the drug excreted in bile is reabsorbed from the intestine (enterohepatic circulation) and may contribute to maintenance of serum levels. Ten to 50 percent of various tetracyclines is excreted into the urine, mainly by glomerular filtration. Ten to 40 percent of the drug is excreted in feces. Doxycycline and tigecycline, in contrast to other tetracyclines, are eliminated by nonrenal mechanisms, do not accumulate significantly and require no dosage adjustment in renal failure. 

The oral dosage for rapidly excreted tetracyclines, equivalent to tetracycline hydrochloride, is 0.25-0.5 g four times daily for adults and 20-40 mg/kg/d for children (8 years of age and older). For severe systemic infections, the higher dosage is indicated, at least for the first few days. The daily dose is 600 mg for demeclocycline or methacycline, 100 mg once or twice daily for doxycycline, and 100 mg twice daily for minocycline. Doxycycline is the oral tetracycline of choice because it can be given as a once-daily dose and its absorption is not significantly affected by food. All tetracyclines chelate with metals, and none should be orally administered with milk, antacids, or ferrous sulfate. To avoid deposition in growing bones or teeth, tetracyclines should be avoided in pregnant women and children less than 8 years of age. 

Several tetracyclines are available for intravenous injection in doses of 0.1-0.5 g every 6-12 hours (similar to oral doses) but doxycycline is the usual preferred agent, at a dosage of 100 mg every 12-24 hours. Intramuscular injection is not recommended because of pain and inflammation at the injection site. 

Dizziness, vertigo, nausea, and vomiting have been noted particularly with doxycycline at doses above 100 mg. With dosages of 200-400 mg/d of minocycline, 35-70% of patients will have these reactions. 

For drugs other than primaquine, begin 1-2 weeks before departure (except 2 days before for doxycycline and Malarone) and continue for 4 weeks after leaving the endemic area (except 1 week for Malarone). All dosages refer to salts. 

Residue studies (253) performed on calves after oral administration at a dosage of 10 mg/kg bw/day for 5 days showed that residues of the drug could remain in kidney and liver tissues for more than 14 days after cessation of the medication. Following a single oral or intravenous administration of doxycycline to chickens at dosage rates of 100 mg/kg or 20 mg/kg bw, respectively, residue... 

The three tetracyclines most recently marketed were made by a semisynthetic pathway. The first of these were methacycline (6-methylene oxytetracycline) (5), C22H22N2OS. and its reduction product doxycycline (6). C22H24CIN2O2- The latter compound is a potent antibiotic which is well-absorbed and slowly excreted, thus allowing small and infrequent (once or twice a day) dosage schedules. Finally, the most recent addition to the commercial tetracyclines is minocycline (7). C21H27N3O7. which is also well-absorbed and slowly excreted. 

Standard dosage for tetracycline is 250 mg four times daily for approximately 4 to 6 weeks. Results of the therapy then are assessed, and the medication is tapered over a more extended period. Doxycycline is as effective as tetracycline when used in a dosage of 100 mg twice daily by mouth over a 3- to 6-week period. As with tetracycline, this dose, if effective, may be tapered to as low as 50 mg/day for approximately 1 month and then to 50 mg every other day for several weeks, as long as effectiveness is sustained. When doxycycline is not effective, the recommended therapy is tetracycline, 250 mg four times daily. Erythromycin may be substituted when treating children with dosing based on the child s age and weight. 

Children Preferred choices Streptomycin, 15 mg kg IM twice daily (maximum daily dose, 2g) Gentamicin, 2.5 mg kg IM or IV three times daily Alternative choices Doxycycline If >45kg, give adult dosage If <45kg, give 2.2mg kg twice daily (maximum, 200mg d- ) Ciprofloxacin, 15 mg kg IV twice daily Chloramphenicol, 25 mg kg IV four times daily" ... 

Children Preferred choice Doxycycline If > to 45 kg, give adult dosage If <45 kg, then give 2.2 mg kg orally twice daily Ciprofloxacin, 20 mg kg orally twice daily Alternative choice Chloramphenicol, 25 mg kg orally four times daUy" - ... 

Doxycycline is commonly used in the treatment of moderate to severe acne vulgaris. It is more effective and produces less resistance than tetracycline. The initial dosage is usually 100 or 200 mg daily, followed after improvement by 50 mg/day as a maintenance dose it may be taken with food even thongh it is more effective when taken 30 minutes before meals. Subantimicrobial-dose doxycycline (20 mg) has been investigated in a double-blind, placebo-controlled trial in the treatment of moderate facial acne. Positive ontcomes were achieved with no development of resistant organisms or change in normal skin flora. Adverse effects include resistant bacteria, folliculitis, candidiasis, gastrointestinal upset, and phototoxic effects such as photo-onycholysis. ... 

ROUTES OF ADMINISTRATION AND DOSAGE A variety of tetracyclines are available for oral, parenteral, and topical administration. Tetracycline, oxytetracycline (TERRAMYCIN, others), demeclocycline (declomycin), minocycline (minocin, others), and doxycycline (vibramycin, others) are available in the U.S. 

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