Pharmacokinetics of Oral and Subcutaneous Carprofen in Common Marmosets (Callithrix jacchus)
The common marmoset (Callithrix jacchus) is an increasingly popular animal model, and while carprofen is a frequently used NSAID in this species, there are no published studies evaluating dosage needs to achieve appropriate analgesia. The aim of this study was to determine the pharmacokinetics of low-dose (2 mg/kg) and high-dose (4 mg/kg) carprofen following oral and subcutaneous routes of administration in marmosets. Three (2 females, 1 male) adult (3.1 ± 1.6 y old [mean ± SD]) common marmosets were used for this study. Blood was collected at 0, 1, 2, 4, 6, 12, and 24 h after administration. The plasma concentrations of carprofen were determined using HPLC and pharmacokinetic parameters. The 4 mg/kg carprofen yielded a significantly higher plasma concentration than did 2 mg/kg carprofen. However, our data show that neither administration route, nor dose, result in plasma concentrations at or above the desired therapeutic threshold. The poor pharmacokinetic properties suggest that these doses of carprofen are not adequate and that either higher doses should be considered or carprofen should not be used as the NSAID of choice in the common marmoset.
Representative skin lesions with mild superficial localized erythema after subcutaneous carprofen injections. Four out of 6 instances when marmosets received subcutaneous carprofen injections, minor lesions developed within 12 h. No swelling was noted at the injection sites, and animals were not observed to experience pain. Lesions were attributed to nonspecific dermatitis.
Plasma concentration–time curve showing mean plasma concentration (error bar, SD) after 2 mg/kg PO (n = 3), 2 mg/kg SC (n = 3), 4 mg/kg PO (n = 3), or 4 mg/kg SC (n = 3) administration in marmosets. The dashed line indicates minimal therapeutic range to reach based on the canine determined therapeutic plasma concentration (10,000 ng/mL = 10 μg/mL).46
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