Letter to the Editor Current Reviews in Clinical and Experimental Pharmacology, 2021, Vol. 16, No. 3 1 Letter to the Editor Is it Possible to Estimate the Bioequivalence between Parenteral and En- teral Formulations of Escin? Luca Gallelli 1,2,* , Erika Cione 3 , Leiming Zhang 4,* and Tian Wang 4 1 Department of Health Science, School of Medicine, University Magna Graecia of Catanzaro, Operative Unit of Clini- cal Pharmacology, Mater Domini University Hospital, Catanzaro, Italy; 2 Research Center FAS@UMG, University Magna Graecia of Catanzaro; 3 Department of Pharmacy, Health and Nutritional Sciences, Department of Excellence 2018-2022, University of Calabria, 87036 Rende (CS), Italy; 4 Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, School of Pharmacy, Yantai University, Yantai, 264005, China Abstract: We suggest that enteral formulation of escin could be used instead of enteral formulation if it is not available. A R T I C L E H I S T O R Y Received: December 24, 2020 Revised: December 24, 2020 Accepted: December 28, 2020 DOI: 10.2174/1574884716666210309103109 Keywords: Escin, enteral formulation, parenteral formulation. Dear Editor Escin is a natural mixture of triterpene saponins used in the treatment of both edema (e.g., after trauma or surgery) and vascular damage [1-3]. To date, 13 clinical studies have been published concerning the effect of escin (beta-escin, amorphous formulation or crystalline formulation for oral or topical administration, respectively) in several clinical conditions. Of these, 4 studies evaluated the role of topical administration (gel formulation), while 9 assessed the role of systemic administration (Ta- ble 1). Concerning the systemic use of escin, 1 of 9 manuscripts described the effect of escin IV alone [4], while 8 reported the effect of IV plus/and oral administration. In Table 1, the studies referring to the sequential combination of IV and oral formu- lation have been reported. In particular, escin is usually used at the defined daily dosage of 10 mg intravenous for 1-3 days and then at 120 mg for 5-7 days as oral formulation. Since the intravenous formulation is not easily available now, we suggest that the initial treatment with the enteral formu- lation at 120 mg/daily could provide a comparable clinical effect. This is related to 2 different points: 1) As described in Table 1, the enteral formulation used after the intravenous treatment is able to improve the clinical out- come in all enrolled patients. 2) In agreement with the literature data, after oral administration of marked amorphous aescin, the amount absorbed from the gastrointestinal tract averaged 12-16% of the administered dose [2, 5]; therefore, for a daily dosage of 120 mg, we may esti- mate that the escin bioavailability corresponds to approximately 14 mg. This quantity is similar to the quantity of 10 mg relat- ed to the use of parenteral administration (10 mg directly administered intravenously, thus with 100% bioavailability) [6-10]. Therefore, it is possible to affirm that the oral formulations are expected to achieve a similar clinical efficacy with respect to the parenteral administration [11-13]. ________________________________________ *Address correspondence to these authors at the Department of Health Science, School of Medicine, University of Catanzaro, Clinical Pharmacology and Pharmacovigilance Unit, Mater Domini University Hospital, Catanzaro, Italy; Tel: +390961712322; E-mail: gallelli@unicz.it and Key Laboratory of Molecu- lar Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, School of Pharmacy, Yantai University, Yantai, 264005, China; E-mail: zhangleiming2009@126.com 1574-8847/21 $65.00+.00 ©2021 Bentham Science Publishers