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RULID

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Roxithromycin(e)

Excipients
Polioxyethylene-polioxypropylene co-polymer, polyvinyl pyrrolidone, hydroxypropyl cellulose, precipitate silica, corn starch, magnesium stearate, talc, propylene glycol, anhydrous glucose, methylhydroxypropyl cellulose, titanium dioxide.

Adverse Effects and Precautions

Gastro-intestinal disturbances are the most frequent adverse effect, but are less frequent than with erythromycin. A case of cholestatic hepatitis has been reported. Rashes, headache, dizziness, weakness and changes in blood cell counts have also occurred. Acute pancreatitis, with duodenal inflammation, pain, pancreatic enlargement and raised serum-amylase developed within 24 hours of substitution of roxithromycin for erythromycin ethyl succinate in a patient being treated for respiratory tract infection. Symptoms resolved rapidly once roxithromycin was withdrawn. Souweine B, et al. Acute pancreatitis associated with roxithromycin therapy. DICP Ann Pharmacother 1991- 25: 1137.

Antimicrobial Action and Resistance

It is reported to be as active or slightly less active than erythromycin. MICs for the most sensitive strains range from about 0.03 to 1 mcg per ml but organisms with MICs up to about 2 mcg per ml are generally considered sensitive.

Pharmacokinetics

Following oral administration roxithromycin is well absorbed, with peak concentrations of about 6 to 8 mcg per ml occurring around 2 hours after a single dose of 150 mg. Absorption is reduced when taken after, but not before, a meal. It is widely distributed in tissues and body fluids. It is reported to be about 96% bound to plasma protein (mainly alpha (1)-acid glycoprotein) at trough concentrations, but binding is saturable, and only about 86% is bound at usual peak concentrations.

Small amounts of roxithromycin are metabolized in the liver, and the majority of a dose is excreted in the faeces as unchanged drug and metabolites- about 7 to 12% is excreted in urine, and up to 15% via the lungs. The elimination half-life is reported to range between about 8 and 13 hours, but may be more prolonged in children.

References

1. Puri SK, Lassman HB. Roxithromycin: a pharmacokinetic review of a macrolide. J Antimicrob Chemother 1987- 20 (suppl B): 89-100. 

2. Periti P, et al. clinical pharmacokinetic properties of the macrolide antibiotics: effects of age and various pathophysiological states (part II). Clin Pharmacokinet 1989- 16: 261-82.

Uses and Administration

Roxithromycin is a macrolide antibiotic with actions and uses similar to those of erythromycin. It is given by mouth in a dose of 150 mg twice daily before meals, in the treatment of susceptible infections. 
1. Phillips I, et al., (eds). Roxithromycin: a new macrolide. J Antimicrob Chemother 1987- 20 (suppl B): 1-187. 

2. Young RA, et al. Roxithromycin: a review of its antibacterial activity, pharmacokinetic properties and clinical efficacy. Drugs 1989- 37: 8-41. Correction. ibid.

3. Bahal N, Nahata MC. The new macrolide antibiotics: azithromycin, clarithromycin, dirithromycin, and roxithromycin. Ann Pharmacother 1992- 26: 46-55.

Lyme Disease

Roxithromycin has been reported to be of benefit in patients with late-stage symptoms (neuroborreliosis, (1) arthritis (2)) of Lyme disease, given in combination with co-trimoxazole, although the contribution of the latter is uncertain. (3)

1. Gasser R, Dusleag J. Oral treatment of late borreliosis with roxithromycin plus co-trimoxazole. Lancet 1990- 336: 1189-90. 

2. Pedersen LM, Friis-Moller A. Late treatment of chronic Lyme arthritis. Lancet 1991- 337: 241. 

3. Bowman CA. Oral treatment of late borreliosis with roxithromycin plus co-trimoxazole. Lancet 1990- 336: 1514.

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