Year of Publication

2018

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Pharmacy

Department

Pharmaceutical Sciences

First Advisor

Dr. Chang-Guo Zhan

Abstract

Cocaine is a plant-based illicit drug commonly involved in substance use disorder. Although cocaine overdose and cocaine use disorders cause adverse health consequences to individuals and the economic burden on their family and society, there are no FDA (Food and Drug Administration) approved medications for treatment. Recently, it has been recognized that delivery of cocaine hydrolase (CocH) is a promising therapeutic strategy. Human butyrylcholinesterase (hBChE), the primary enzyme involved in cocaine metabolism in human, have advantages over other candidates for the development of CocH. Previous studies in our laboratory have designed and characterized hBChE mutants that have ~4,000-fold improved catalytic efficiency against naturally occurring (-)-cocaine as compared to the wild-type hBChE. Besides the catalytic efficiency, the biological half-life is another essential factor that influences the desired therapeutic value in the long-term treatment of cocaine use disorder. In order to provide prolonged effects to reduce administration frequency in clinical use, efforts have been made to increase the retention time of CocHs in blood circulation by fusing CocHs with other thermostable proteins or their mutants, including human serum albumin (Albu) or the Fc region of the human IgG (Fc).

In this dissertation, we demonstrated the clinical potential and the benefits of long-lasting CocHs for cocaine overdose treatment. We used rodent models to show the ability of AlbuCocH1 to block or reverse manifestations of toxic effects of cocaine. In addition, a concomitant LC-MS/MS-based analysis was conducted to investigate the pharmacokinetic profile of a lethal dose of cocaine with the presence of AlbuCocH1. These experimental data demonstrated AlbuCocH1 as an effective cocaine detoxification agent by accelerating the metabolism of cocaine.

In order to examine the potential therapeutic value of Fc-fused CocHs in the treatment of cocaine use disorder, we conducted a series of behavioral experiments in rats to evaluate the effectiveness and duration of Fc-fused CocHs in blocking or attenuating cocaine-induced psychostimulant and discriminative stimulus effects. In addition, the intravenous self-administration model was used to investigate the long-term effectiveness of Fc-fused CocHs in blocking or attenuating the reinforcing effects of cocaine. It has been shown that a single dose of E30-6-Fc (3 mg/kg) was able to effectively alter the cocaine dose-response curve and attenuate the reinforcing efficacy of cocaine for at least a month in both male and female rats.

In summary, AlbuCocH1 (TV-1380), which failed to meet the primary efficacy endpoint in clinical trials for facilitating abstinence in cocaine-dependent subjects with a weekly dosing schedule (due to the short biological half-life), is more suitable to be developed as a cocaine detoxification agent. On the contrary, the newly designed Fc-fused CocH (e.g. CocH3-Fc, E30-6-Fc) with higher catalytic efficiency and longer biological half-life will be beneficial for long-term abstinence management in cocaine-dependent individuals.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2018.368

Available for download on Friday, September 11, 2020

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