Brand
Zithromax
Availability
100 mg/5mL oral suspension
200 mg/5mL oral suspension
500 mg powder for injection
250 mg & 600 mg tablets
Pharmacology
Azithromycin is an azolide which is a subclass of the macrolide antibiotics. It is derived from erythromycin, but its chemical structure differs slightly by having a methyl-substituted nitrogen atom in the lactone ring. Azithromycin has the ability to block protein synthesis.
This drug is primarily bacteriostatic, but can be bactericidal depending on the
concentration given. Effective against aerobic gram positive microorganisms, and some gram negative.
Azithromycin is absorbed both widely and rapidly throughout the body. When distributed in the body, concentrations are found to be greater in tissue compared to that of plasma and serum levels.
The drug is metabolized in the liver and excreted in the urine.
Indications
Use for infections brought about by Mycobacterium, Mycoplasma, Chlamydia, and Rickettsia. More effective with acute outbreaks in younger rats.
May require the use of a second antibiotic like doxycycline, when given in older rats, for chronic respiratory infection.
Drug Interactions or Contraindications
Decreased absorption with aluminum and magnesium containing drugs. Increased effect/toxicity levels when used with digoxin, and theophylline.
Do not give when there is impaired liver function.
Adverse Reactions
EENT: ototoxicity
GI: diarrhea, loss of appetite.
GU: nephritis
Other: stroke
Dosage Recommendations
4 mg/lb to 8 mg/lb BID first 14 days then SID for additional 14 days if needed.
4
or
4mg/lb BID for 2 weeks, then SID for 2weeks. 3
Safe for use in pregnant does and rats under 4 months. See Raisin’ Rats Rattery, http://www.raisinrats.com/medicalinfo.html; M.Ruud, Breeder, RMCA Member
Considerations
Drug recommendation is to give on empty stomach(1-2 hours before meal or 2 hours after meals)to prevent interference with absorption of the antibiotic.
Some drugs are known to be better absorbed without food, but unless a rat is in a hospital enviroment we realize that this is impossible for the pet rat owner. It is believed to be far more important to get the medication into the rat, even if you have to mix it in a favorite food, than to worry about whether food will hinder the medications absorption rate.
May cause superinfections when used over long period of time.
Reconstituted solution good for 7 days if refridgerated.
Note:some reports have indicated a limited response in older rats with more chronic or advanced problems. The drug is reported to be more effective when used in young rats.
Recent studies with humans, both adult and pediatric, indicate that single dose, or high dose day one with lower dose day 2-5 appear equally as effective in treating certain disease processes. Side effects were more commonly reported with single and short term dosing.
References
Pediatric Pharmacotherapy
Marcia L. Buck, Pharm. D.; FCCP
http://www.healthsystem.virginia.edu/internet/pediatrics/pharma-news/apr2005.pdf
Zithromax
http://www.pfizer.com/download/uspi_zithromax.pdf
Posted on June 23, 2003, 14:28,
Last updated on March 17, 2008, 16:48
| Antimicrobial Agents
