Tiamulin

Introduction:Tiamulin is a semisynthetic pleuromutilin diterpene veterinary antibiotic, widely used in farms. We present a case of prolonged QT-interval and ventricular tachyarrhythmia after tiamulin inhalation.Case presentation:A 43-year-old veterinarian without previous medical history was dividing granulated powder of antibiotic gravimetrically without wearing personal protective equipment. Half an hour after exposure, nausea occurred; four hours later he started to vomit and soon after that he experienced syncope. He was unconscious three minutes; afterwards he became somnolent, dizzy and nauseated with sweating and salivation. On admission to hospital five hours after exposure, he was conscious and had heart rate 70 beats/min and blood pressure 140/80 mmHg. Initial laboratory results were normal. Electrocardiography showed a prolonged QTc-interval of 730 ms with numerous polymorphic ventricular extrasystoles and episodes of non-sustained polymorphic ventricular tachycardia that resolved after treatment with lidocaine and magnesium. Subsequent electrocardiography revealed gradual shortening of QTc-interval with QTc-interval normalization (430 ms) between 24 and 32 hours after tiamulin exposure. Laboratory tests, morphologic heart diagnostics and genetic testing excluded other potential causes of QTc-interval prolongation. Subsequent toxicology analysis by LC-MS/MS confirmed tiamulin in his serum samples on admittance (500 ng/mL).Conclusion:Tiamulin inhalation can be associated with prolonged QT-interval and ventricular tachyarrhythmia. QT-interval prolongation could be expected in overdoses of emerging human pleuromutilins.

Mass medication to manage population health can be achieved by providing therapeutics in the drinking water. Young nursery pigs are highly sensitive to the flavor and smell of water. Medications that reduce water palatability often lead to an interruption in water and feed intake. With the availability of several generic water-soluble antimicrobials for pigs, questions have arisen about their palatability compared with the original product. In this study, we compared the intake of water containing tiamulin hydrogen fumarate from two different manufacturers with the intake of unmedicated water. The hypothesis was that the intake of tiamulin-containing water would be similar to unmedicated water. Water intake was monitored upon entry into the nursery and just prior to leaving the nursery. Also, average daily gain (ADG) and feed efficiency (FE) were determined. A total of 300 pigs were individually weighed (4.2-10.9 kg; avg = 6.8 kg) for randomization to pen (n= 30 pens). The experiment had two time points: 1) early nursery (periods 1-3) and 2) late nursery (period 4). Pens were randomly assigned to a sequence (period 1-3) in a crossover experimental design containing three 10-d periods, with 5 d for the resetting of baseline where unmedicated water was provided followed by 5 d on tiamulin source addition [i.e., TriamuloxTM(Zoetis, Parsippany, NJ); Denagard (Elanco Animal Health, Greenfield, IN)] or unmedicated water. After period 3 was concluded, all pens were given unmedicated water (via nipple waterers) and the number of pigs per pen was reduced to six pigs to maintain adequate space per pig. Ten days prior to pigs leaving the nursery, a fourth period was performed. After a 5-d water baseline was achieved, pens were treated with either unmedicated water or Triamulox- or Denagard-containing water. Pigs had ad libitum access to water and feed. During the testing periods, daily water intake was measured by a cup water system in each pen. Feed intake was measured every 5 d. There was no effect of treatment on initial body weights or weights at the beginning or end of each period (P≥ 0.51). Therefore, there was no effect of treatment on ADG (P≥ 0.23). Water intake (P≥ 0.16) and FE (P≥ 0.35) were not affected by treatment. Water consumption was similar among all treatments in each of the four periods. There appears to be no aversion to water intake when tiamulin hydrogen fumarate is added to the drinking water.

The pharmacokinetics of tiamulin were studied in 2 groups of ducks (n= 6) after its oral administration at 2 different doses (30 and 60 mg/kg, respectively). Plasma concentrations of tiamulin were measured by high performance liquid chromatography at different time points up to 24 h post-administration. The maximum plasma concentrations were 0.77 and 2.32 μg/mL attained at 2 h (Tmax) for 30 and 60 mg/kg, respectively. The elimination half-lives for these 2 doses were 3.54 and 6.34 h, respectively. The minimum inhibitory concentration for tiamulin againstMycoplasma anatis(M. anatis) strain 1340 was determined to be 0.06 μg/mL. The proper oral dose of tiamulin againstM. anatisin ducks was calculated to be 35 mg/kg/day using the pharmacokinetic/pharmacodynamic modeling. Tiamulin was administered orally (40 mg/kg/day) to 30 ducks for 3 successive days to determine its residues in edible tissues and its preslaughter withdrawal time. The highest tiamulin residues were detected in the liver, followed by the muscle, whereas lower concentrations were detected in the skin and fat. The estimated withdrawal periods of tiamulin were 6, 5, 3, and 3 days for liver, muscle, skin, and fat, respectively. Therefore, an oral dosage regimen of 35 mg/kg/day should be adequate for tiamulin againstM. anatis. We recommend a preslaughter withdrawal period of 6 days when ducks are treated with 40 mg tiamulin/kg/day, orally, for 3 days.