Bajwa N S, Bansal B K, Srivastava A K, Ranjan R
Department of Clinical Veterinary Medicine, Ethics and Jurisprudence, College of Veterinary Sciences, Punjab Agricultural University, Ludhiana, Punjab, India.
Vet Res Commun. 2007 Jul;31(5):603-10. doi: 10.1007/s11259-007-3505-7. Epub 2007 Jan 15.
The pharmacokinetics of erythromycin was studied in five lactating dairy cows following single intramammary infusion of 300 mg erythromycin in each of two quarters per cow with specific mastitis. Levels of erythromycin in plasma and quarter milk samples were measured by agar plate diffusion assay using Micrococcus luteus (ATCC 9341) as the test organism. Erythromycin level in plasma reached a peak concentration value (C(max)) of 0.07 +/- 0.01 microg/ml at 30 min; thereafter, levels declined gradually to reach 0.05 +/- 0.00 microg/ml 12 h post drug administration. The pharmacokinetic profile of the drug revealed mean absorption half life (t(1/2 ka)) as 0.26 +/- 0.05 h. The drug was eliminated slowly with elimination half-life (t(1/2 beta)) of 13.75 +/- 0.35 h and elimination rate constant (k(el)) of 0.04 +/- 0.00 h(-1). The volume of distribution based on the zero-time plasma concentration intercept of the least-squares regression line of the elimination phase (V(d(B))) was 0.032 L/kg. The drug crossed to untreated quarters also; mean drug levels of 0.20 +/- 0.07, 0.23 +/- 0.07, 0.17 +/- 0.04, and 0.17 +/- 0.04 microg/ml were found at 3, 6, 8 and 12 h, respectively. The mean drug concentration for treated quarters was measured as 22.97 +/- 2.31 microg/ml milk at first milking (12 h) following drug infusion. No apparent adverse reaction was seen in cows administered erythromycin. It is concluded that following intramammary infusion erythromycin diffuses readily and extensively in various body fluids and tissues and adequate concentration is maintained in udder tissues for at least 12 h post intramammary administration. Thus, erythromycin may be recommended for local therapy of acute mastitis caused by Gram-positive bacteria in lactating dairy cows.
在五头患有特定乳腺炎的泌乳奶牛中，每头牛的两个乳腺区各单次乳房内注入300毫克红霉素后，对红霉素的药代动力学进行了研究。血浆和乳腺区乳样中的红霉素水平通过琼脂平板扩散法测定，使用藤黄微球菌（ATCC 9341）作为测试微生物。血浆中的红霉素水平在30分钟时达到峰值浓度值（C(max)）0.07±0.01微克/毫升；此后，水平逐渐下降，给药后12小时降至0.05±0.00微克/毫升。该药物的药代动力学特征显示平均吸收半衰期（t(1/2 ka)）为0.26±0.05小时。药物消除缓慢，消除半衰期（t(1/2 beta)）为13.75±0.35小时，消除速率常数（k(el)）为0.04±0.00小时⁻¹。基于消除相最小二乘回归线的零时间血浆浓度截距的分布容积（V(d(B))）为0.032升/千克。药物也会扩散到未处理的乳腺区；在3、6、8和12小时分别发现平均药物水平为0.20±0.07、0.23±0.07、0.17±0.04和0.17±0.04微克/毫升。在药物注入后的首次挤奶（12小时）时，处理过的乳腺区的平均药物浓度测定为22.97±2.31微克/毫升乳。给奶牛施用红霉素后未观察到明显的不良反应。得出的结论是，乳房内注入红霉素后，它很容易且广泛地在各种体液和组织中扩散，并且在乳房内给药后至少12小时内乳房组织中维持足够的浓度。因此，红霉素可推荐用于泌乳奶牛由革兰氏阳性菌引起的急性乳腺炎的局部治疗。
