Effect of Thermal History on Abuse Deterrence Performance

Nova Southeastern University, Davie, Florida, USA

Objective. This study conducted to determine the effect of thermal treatment on solid methylcellulose (MC), carboxymethylcellulose (CMC), and poly(ethylene oxide) (PEO) polymers on their gel forming properties in solution state. Background. Heating is a common technique employed by abusers to circumvent deterrence mechanisms of abuse deterrent formulations. Heat causes long polymeric chains of PEO to break, resulting in reduced viscosity. Thus, PEO based formulations possess high risk of IV abuse when manipulated by heat such as with microwaving. Methods. PEO, CMC and MC (500 mg) were exposed to different heating temperatures of 80, 110, 150, and 180oC using an air-recirculated oven for 1 hr. An aqueous 2% w/v solution of the samples was prepared. Also, a control solution for each polymer was prepared using a non-heated polymer sample. The viscosities of all solutions (control and heat-treated) were measured using a cone and plate rheometer (Brookfield DV-III Ultra) at a shear rate of 300 sec-1 for 40 sec. Results. The control solutions of MC showed lowest viscosity values. However, the PEO solutions showed lowest viscosity values under all heating treatments. Viscosity values of CMC solutions (>150oC), were higher than maximum detection limit of the experimental set up. The MC solutions showed a gradual drop in viscosity and showed highest viscosity values (194.8 ± 1.8 cP at 180oC). Conclusion. Thermal history severely affects the gel formation, hence IV abuse of PEO. MC and CMC show relatively stable viscosities, as such may prove more beneficial as an abuse deterrent agent than PEO alone.