The effect of food deprivation on the rate of sulfamethazine elimination in goats

Effects of starvation on the pharmacokinetics and optimal dosages of florfenicol and associated serum biochemistry in Asian seabass (Lates calcarifer)

Starvation has influence on physiology and pharmacokinetic (PK) characteristics of many drugs in land animals. However, similar PK information in fish is lacking. The current study examined the effects of starvation on fish PK, taking florfenicol (FF) in Asian seabass as an example. FF was orally administered at a single dose of 10 mg/kg into 35-day starved fish reared at 25 and 30°C and the serum FF concentration was analyzed by HPLC-FLD. At 30°C, the absorption and elimination half-lives of the starved fish were increased by 30% (from 0.44 to 0.57 h) and 55% (from 7.2 to 11.18 h), respectively. The volume of distribution, clearance, and area under the curve were changed from 1.25 to 0.71 L/kg, 0.120 to 0.044 L/kg/h, and 88 to 228 h·μg/ml, respectively. Similar starvation-induced PK changes were also observed at 25°C. The serum biochemical parameters, mainly the alanine aminotransferase, aspartate aminotransferase, and glucose levels, were significantly reduced in the starvation group. Overall, FF absorption, distribution, and elimination rates were reduced by starvation, resulting in four to five times lower optimal dosage than the non-starved fish. Drug treatment in starved fish should be treated with caution as overdosing and/or tissue residues could perceivably occur.

Interspecies variations in plasma half-life of ampicillin, amoxycillin, sulphadimidine and sulphacetamide related to variations in body mass

The relationships between the half-lives during the elimination phase (t1/2 minutes) of ampicillin, amoxycillin, sulphadimidine and sulphacetamide and body mass (W, kg) between species of mammals and birds were examined using data from the authors' experiments and collected from the literature. Linear regression of the log half-lives of ampicillin, amoxycillin and sulphadimidine following intravenous injection on the log body mass for a variety of species of mammals and birds revealed significant correlations (r = 0.7709, n = 8, r = 0.7712, n = 8, r = 0.7749, n = 10). The interspecies relationships were described by the allometric equations t1/2 = 31.3 W0.16, t1/2 = 32.7 W0.12 and t1/2 = 129.2 W0.28, respectively. These equations may be of value for estimating dose intervals in species for which no relevant pharmacokinetic data are available.