Assessing the safety of an Ephedrae Herba aqueous extract in rats: A repeat dose toxicity study

Highlights

• There is little data in the literature on the toxic effects of Ephedrae Herba.

• Three males and two females in the highest dose group (1000 mg/kg bw/day) were found dead at weeks 1 and 9.

• In macroscopic observation, test article-related changes were observed in the kidneys and salivary glands.

• The no-observed-adverse-effect level was determined as 125 mg/kg bw bw/day for both sexes.

Abstract

Ephedrae Herba (EH) has been used in Asian traditional herbal medicine to cure bronchial asthma, cold, flu, chills, fever, headache, nasal congestion, and cough. In this study, we evaluated the subchronic toxicity of an Ephedrae Herba aqueous extract (EHAE) in male and female F344 rats. The EHAE was administered orally daily at doses of 0, 125, 250, 500, and 1000 mg/kg bw/day for 13 weeks. Toxicological assessment was performed to determine mortality, clinical signs, and changes in body weight, food consumption, ophthalmological, urinary, hematological, and serum biochemical parameters, macroscopic and microscopic evaluations, and organ weights. We found that oral administration of EHAE to F344 rats for 13 weeks resulted in histopathological changes in the kidneys and salivary glands. In the kidneys, increased incidence and severity of tubular basophilia were observed in females administered 1000 mg/kg bw/day of the extract. In the salivary glands, acinar cell hypertrophy was observed in males administered 500 mg/kg bw/day and in both sexes administered 1000 mg/kg bw/day of the extract. All test article-treated groups of males and females administered ≥250 mg/kg bw/day showed increased absolute and relative salivary gland weights. Therefore, the NOAEL (No Observed Adverse Effect Level) was determined as 125 mg/kg bw/day for both sexes of rats under the present experimental conditions.

Introduction

Ephedrae Herba includes the species Ephedra sinica Stapf., E. intermedia Schrenk et Meyer, and E. equisetina Bge., which belong to the family Ephedraceae. They have been used to treat nasal congestion due to hay fever, allergic rhinitis, acute coryza, common cold, and sinusitis in traditional Asian medicine for several thousand years (Soni et al., 2004). Ephedrae Herba (EH) contains two main active constituents, ephedrine and pseudoephedrine, which are potent sympathomimetic drugs that stimulate α-, β₁-, and β₂-adrenoceptors (Vansal and Feller, 1999, Ma et al., 2007). Ephedrine can be primarily isolated from the aerial parts of the Ephedra species or chemically synthesized in a laboratory (Abourashed et al., 2003, Gurley et al., 1998). Ephedrine stimulates heart rate as well as cardiac output and increases peripheral resistance, producing a lasting increase in blood pressure (Abourashed et al., 2003).

A review of 140 case studies reported that dietary supplements containing ephedra alkaloids have been widely consumed in the United States for weight loss and energy enhancement (Haller and Benowitz, 2000). However, their usage may pose a health risk to some people because ephedra and related alkaloids are associated with adverse cardiovascular events. Given the frequency of reports on these effects, including infarction, stroke, and sudden death, the Food and Drug Administration (FDA) has banned the sale of ephedra-containing dietary supplements since 2004 (Haller and Benowitz, 2000, Soni et al., 2004). Intensive studies on ephedrine (a major ingredient of EH) using rats and mice have been published (Dunnick et al., 2007). However, subchronic and chronic animal studies including scientific toxicity analyses of the Ephedra plant are lacking. Therefore, this study elucidated scientific data on the toxicity of EH and its appropriate usage to avoid misuse and prevent unexpected accidents in humans.

As part of the safety assessment, we evaluated the subchronic toxicological effects of EHAE by oral administration to F344 rats for 13 weeks. This study was conducted according to guidelines established by the Organization for Economic Cooperation and Development (OECD) for testing chemicals in accordance with modern Good Laboratory Practice (GLP) regulations. Treatment-related changes developed with respect to mortality, body weight, clinical signs, serum chemistry, organ weight, and histopathology. Thus, we proposed the appropriate use of EHAE with respect to dosage and duration of treatment.