The pharmacokinetics of cefadroxil in the foal

Duffee, Nicole; Christensen, J. Mark; Craig, A. Morrie

doi:10.1111/j.1365-2885.1989.tb00678.x

Cited by 16 publications

(6 citation statements)

References 7 publications

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“…Even though poor bioavailability was apparent in the adult horses of this study, orally administered acyclovir has been used with apparent success in the management of the neonatal form of the disease according to one report 14 . There is a possibility that neonates absorb the drug better than adults, which has been shown for other orally administered antimicrobials in horses 29 …”

Section: Discussionmentioning

confidence: 73%

Pharmacokinetics of acyclovir in adult horses

Wilkins¹,

Papich²,

Sweeney³

2005

J Vet Emergen Crit Care

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Objective: To determine the pharmacokinetics of acyclovir administered intravenously (IV) and orally to healthy adult horses. Design: Random cross-over with an approximate 1-week washout period between trials. Setting: University veterinary medical teaching hospital. Animals: Six healthy adult research herd horses. Interventions and main results: Acyclovir was administered IV (10 mg/kg in 1 L isotonic crystalloid solution over 60 minutes) and orally (20 mg/kg) to healthy adult horses. Plasma samples were obtained and acyclovir concentrations were determined by high-pressure liquid chromatography. Peak concentration (mean AE SD) for IV acyclovir was 13.74 AE 5.88 mg/mL at the completion of the 1-hour infusion. The half-life of the distribution phase (a) was 0.16 hours while the half-life of the elimination phase (b) was 9.6 hours. The steadystate volume of distribution was 3.93 AE 1.21 L/kg. We were unable to measure pharmacokinetics after PO acyclovir as plasma concentrations were below the lower limits of detection in all 6 horses. Conclusions: IV administration of acyclovir to healthy adult horses achieves concentrations within the sensitivity range described for equine herpes virus-type 1. The oral bioavailability of acyclovir in horses is low and additional studies are required. (J Vet Emerg Crit Care 2005; 15(3): 174-178)

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Section: Discussionmentioning

confidence: 73%

Pharmacokinetics of acyclovir in adult horses

Wilkins¹,

Papich²,

Sweeney³

2005

J Vet Emergen Crit Care

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“…Dosage regimens for oral cefadroxil in foals have been published, however, absorption in the adult horse was both poor and inconsistent (Wilson et al. , 1985; Duffee et al. , 1989).…”

Section: Introductionmentioning

confidence: 99%

“…The administration of oral cephalosporin antibiotics in the adult horse has received little attention. Dosage regimens for oral cefadroxil in foals have been published, however, absorption in the adult horse was both poor and inconsistent (Wilson et al, 1985;Duffee et al, 1989). Similarly, cephadrine has been studied in neonatal foals for oral dosing, but no data exists on the drug in adult horses and cephradine is currently unavailable (Henry et al, 1992).…”

Section: Introductionmentioning

confidence: 99%

Pharmacokinetics and tissue fluid distribution of cephalexin in the horse after oral and i.v. administration

Davis¹,

Salmon

Papich³

2005

Vet Pharm & Therapeutics

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The purpose of this study was to determine the pharmacokinetics and tissue fluid distribution of cephalexin in the adult horse following oral and i.v. administration. Cephalexin hydrate (10 mg/kg) was administered to horses i.v. and plasma samples were collected. Following a washout period, cephalexin (30 mg/kg) was administered intragastrically. Plasma, interstitial fluid (ISF) aqueous humor, and urine samples were collected. All samples were analyzed by high-pressure liquid chromatography (HPLC). Following i.v. administration, cephalexin had a plasma half-life (t(1/2)) of 2.02 h and volume of distribution [V(d(ss))] of 0.25 L/kg. Following oral administration, the average maximum plasma concentration (C(max)) was 3.47 mug/mL and an apparent half-life (t(1/2)) of 1.64 h. Bioavailability was approximately 5.0%. The AUC(ISF):AUC(plasma) ratio was 80.55% which corresponded to the percentage protein-unbound drug in the plasma (77.07%). The t(1/2) in the ISF was 2.49 h. Cephalexin was not detected in the aqueous humor. The octanol:water partition coefficient was 0.076 +/- 0.025. Cephalexin was concentrated in the urine with an average concentration of 47.59 microg/mL. No adverse events were noted during this study. This study showed that cephalexin at a dose of 30 mg/kg administered orally at 8 h dosage intervals in horses can produce plasma and interstitial fluid drug concentrations that are in a range recommended to treat susceptible gram-positive bacteria (MIC < or = 0.5 microg/mL). Because of the low oral bioavailability of cephalexin in the horse, the effect of chronic dosing on the normal intestinal bacterial flora requires further investigation.

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“…Pro-drug formations of such drugs enhance oral bioavailability. Cefadroxil is absorbed better in the foal than adult horses (Dufee et al, 1989). Most of the other cephalosporins are either administered IV or IM.…”

Section: Cephalosporinsmentioning

confidence: 99%