Pharmacotherapeutic group: antibacterials for systemic use, lincomycin combinations.
ATCvet code: QJ01FF52
Pharmacodynamic properties
The veterinary medicinal product is a combination of two antibiotics, lincomycin and spectinomycin, having a complementary spectrum of activity.
Lincomycin
Lincomycin is active against gram-positive bacteria, some anaerobic gram-negative bacteria and mycoplasmas. It has little or no action against gram-negative bacteria such as Escherichia coli.
Spectinomycin
Spectinomycin is an aminocyclitol antibiotic derived from Streptomyces spectabilis, it has bacteriostatic activity and is active against Mycoplasma spp. and against some gram-negative bacteria such as Escherichia coli.
The mechanism by which spectinomycin administered orally acts on pathogens at the systemic level despite a poor absorption is not fully elucidated, and might rely partly on indirect effects on the gut flora.
In Escherichia coli the MIC distribution appears to be bimodal, with a significant number of strains showing high MIC values; this could partly correspond to natural (intrinsic) resistance.
In vitro studies as well as clinical efficacy data show that the lincomycin-spectinomycin combination is active against Lawsonia intracellularis.
Due to technical constraints the susceptibility of Lawsonia intracellularis is difficult to test in vitro, and data about the resistance status in that species are lacking.
Pharmacokinetic particulars
Lincomycin
In pigs, lincomycin is rapidly absorbed following oral administration. A single oral administration of lincomycin hydrochloride, at dose levels of approximately 22, 55 and 100 mg/kg body weight in pigs, resulted in dose related lincomycin serum levels, detected for 24–36 hours after administration. Peak serum levels were observed at 4 hours after dosing. Similar results were observed following single oral doses of 4.4 and 11.0 mg/kg body weight in pigs. Levels were detectable for 12 to 16 hours, with peak concentrations occurring at 4 hours. A single oral dose of 10 mg/kg body weight was administered to pigs to determine the bioavailability. The oral absorption of lincomycin was found to be 53% ± 19%.
Repeated dosing of pigs with daily oral doses of 22 mg lincomycin/kg body weight for 3 days indicated no accumulation of lincomycin in the species, with no detectable serum levels of antibiotic after 24 hours post administration.
Lincomycin pharmacokinetic studies in pigs show that lincomycin is bioavailable when given intravenously, intramuscularly or orally. The average of the half-lives of elimination of all routes of administration is 2.82 hours in pigs.
In chickens treated with the veterinary medicinal product in drinking water at the target dose of 50 mg/kg body weight of total activity (at a ratio of 1:2 lincomycin:spectinomycin) for seven consecutive days, Cmax after first offering of medicated water was calculated to be 0.0631 µg/ml. Cmax occurred at 4 hours after introduction of the medicated water.
Spectinomycin
Studies performed in various animal species have demonstrated that spectinomycin undergoes limited absorption from the intestine (less than 4–7%) after oral administration. Spectinomycin exhibits little tendency to protein binding and is poorly liposoluble.