Peer-reviewed veterinary case report
Doxycycline levels in compounded pet medicine after 28 days storage
By Papich, Mark G et al.·Published in Journal of the American Veterinary Medical Association·2013·Department of Molecular Biomedical Sciences, United States·View original on PubMed →
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Original publication title: Doxycycline concentration over time after storage in a compounded veterinary preparation.
Plain-English summary
A study found that a liquid form of doxycycline, a common antibiotic for pets, loses its effectiveness after about a week. The researchers prepared this medication from crushed tablets and stored it at room temperature and in the refrigerator. While the concentration of doxycycline was acceptable for the first week, it dropped significantly by day 14 and remained low afterward. This means that if your veterinarian prescribes a compounded doxycycline liquid for your pet, it’s best to use it within a week for it to be effective.
People also search for: doxycycline for dogs · how long is compounded doxycycline good for · pet antibiotic storage guidelines
Abstract
OBJECTIVE: To determine the concentration of doxycycline compounded from doxycycline hyclate tablets into liquid formulations for oral administration in veterinary species and stored for 28 days. DESIGN: Evaluation study. SAMPLE: Doxycycline hyclate tablets (100 mg) crushed and mixed with a 50:50 mixture of syrup and suspension vehicles for oral administration to produce 3 batches each of 2 doxycycline formulations: 33.3 and 166.7 mg/mL. PROCEDURES: Formulations were stored, protected from light, at room temperature (22° to 26°C [71.6° to 78.8°F]) and at a controlled cold temperature (refrigerated 2° to 8°C [35.6° to 46.4°F]). Doxycycline was extracted from the formulations, and concentration was measured by high-pressure liquid chromatography on days 0 (date of preparation), 1, 4, 7, 14, 21, and 28. Concentrations were compared with those of a US Pharmacopeial Convention reference standard. Formulation quality at each point was also assessed through color change, formulation consistency, and suspension uniformity. RESULTS: On days 0, 1, 4, and 7, the concentration of each formulation was within 90% to 110% of the reference standard (range, 93% to 109%), which was deemed acceptable. However, doxycycline concentrations had decreased dramatically by day 14 and remained low for the duration of the study period. Doxycycline concentrations on days 14, 21, and 28 were all < 20% (range, 14% to 18%) of the reference standard, and the quality of the formulations decreased as well. No effect of storage temperatures on doxycycline concentration was identified. CONCLUSIONS AND CLINICAL RELEVANCE: The concentration of doxycycline, compounded from commercial tablets in the vehicles evaluated to yield doses of 33.3 and 166.7 mg/mL, cannot be assured beyond 7 days.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/23725430/