A substance made available throughout the day can produce a different exposure pattern from a scheduled dose. Abraham and colleagues developed a system that allowed mice to consume gelatin containing THC, CBD or morphine voluntarily. They used a real-time measurement system to record intake and tested serum for the administered compounds.
Mice consumed gelatin during both light and dark periods. The mice offered THC gelatin consumed less than the other treatment groups. Tracking the amount consumed therefore added information that the formulation alone could not provide. Serum testing confirmed exposure and addressed a separate question from how much gelatin disappeared from the dispenser.
The researchers used the setup in a mouse model of sciatic nerve injury. Their method illustrates what an exposure study gains by recording when and how much was consumed. The resulting patterns are specific to the animal model and the way the drugs were offered.