Shear-Thinning Rheology of the Abuse-Deterrent Dosage Form Extracts

Prescription drug abuse has become a worldwide public health issue. Of particular concern is the dose-dumping effect caused by co-ingestion of ethanol which leads to premature rapid release of the drug load. Also, medications can be crushed and dissolved in ethanol for extraction to allow for parenteral routes of administration. To combat this abuse, the pharmaceutical industry has begun to develop dosage forms that are abuse deterrent. In this study, we investigated the use of a cone-and-plate rheometer to evaluate the rheological properties of polyethylene oxide (a common excipient in abuse deterrent dosage forms) in water-alcohol mixtures. This polymer prevents rapid drug dissolution in alcohol by forming a viscous gel in the presence of solvents to discourage intravenous abuse. Our results showed that 2% w/v polyethylene oxide in hydro-alcoholic solvents behaved non-Newtonian. Rheograms showed a non-linear profile where apparent viscosity was decreased as a function of increasing shear rate, and was fit to a Herschel-Bulkley fluid model.

The greater viscosities seen in test solutions at low shear rates may prevent rapid ethanol dissolution of drug, and provide difficulty when dissolving a product in hydro-alcoholic solutions. However, high shear rates such as that seen in rapid mixing or in a needle and syringe are likely to adversely affect the deterrence capacity of polyethylene oxide in solutions.

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