Gaita F, Bocchiardo M, Brossa C, Molinatti G M, Rosettani E, Brusca A
G Ital Cardiol. 1980;10(7):836-42.
The mechanism of reduced sensitivity to digitalis in patients with hyperthyroidism has been attributed to a change of intrinsic myocardial function and/or to altered pharmacokinetics of cardiac glycosides. Digoxin kinetics have been studied in hyperthyroid and 8 euthyroid patients after a single oral and i.v. dose at steady-state. Plasma and urinary digoxin concentrations were determined by radioimmunoassay. A significantly mean lower serum digoxin concentration was found in hyperthyroid patients, both after a single oral drug administration and at the steady-stage. A decreased digoxin absorption could not account for this finding, since both the percentage of gastrointestinal uptake of the drug and maximal serum concentration did not differ in hyperthyroid patients as compared to controls. Hyperthyroid subjects showed, on the contrary, an expended distribution volume and a significantly higher excretion, as documented by a lower drug half-life, by the increase of the elimination constant and urinary digoxin output.
甲状腺功能亢进患者对洋地黄敏感性降低的机制被认为是由于心肌内在功能的改变和/或强心苷药代动力学的改变。对甲状腺功能亢进患者和8名甲状腺功能正常的患者在单次口服和静脉注射达到稳态剂量后进行了地高辛动力学研究。通过放射免疫测定法测定血浆和尿液中的地高辛浓度。在单次口服给药后和稳态期，甲状腺功能亢进患者的血清地高辛浓度均显著低于正常水平。地高辛吸收减少并不能解释这一发现，因为与对照组相比，甲状腺功能亢进患者的药物胃肠道摄取百分比和最大血清浓度并无差异。相反，甲状腺功能亢进患者表现为分布容积增大和排泄显著增加，这表现为药物半衰期缩短、消除常数增加和尿地高辛排出量增加。
