Karan S M, Lojeski E W, Haynes D H, Bina S, Wesche D L, Boedeker B H, Muldoon S M
Department of Anesthesiology, F. Edward Herbert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA.
Anesth Analg. 1996 Apr;82(4):796-802. doi: 10.1097/00000539-199604000-00021.
Dantrolene effectively treats malignant hyperthermia (MH) hut the current form, Dantrium, must be dissolved to a 0.33 mg/mL, pH 9.5 solution. This study describes lecithin-coated microcrystal formulations of sodium dantrolene (MC-NaD) and neutral dantrolene (MC-D) which reconstitute to 200 mg/mL within 1 min. In rats, the pharmacokinetics and pharmacodynamics of MC-NaD and Dantrium were similar: half-lives of 3.1 h, volume distributions of 0.54 and 0.59 L/kg, and 95% effective dose (ED95) values for depression of skeletal muscle twitch height (ED95T) of 2.6 +/- 0.7 and 2.8 +/- 0.5 mg/kg. In swine, the ED95T values for MC-NaD and Dantrium were also similar (2.8 +/- 0.4 vs 2.7 +/- 0.6 mg/kg), but MC-D and Dantrium were only similar at doses more than 2.5 mg/kg (ED95T: 3.5 +/- 0.4 vs 2.7 +/- 0.5 mg/kg). In susceptible swine, MC-NaD successfully treated five of six MH episodes and prevented MH in three of four swine. However, MC-NaD caused marked pulmonary hypertension in swine, while MC-D caused only a mild response that was eliminated by filtration. Likewise, MC-D caused no pulmonary response in dogs. These observations suggest that MC-D has potential to improve the treatment of MH.
