A sub-plantar administration of a chemical irritant such as formalin or carrageenan induces pain and inflammation in mice. These tests can be used to determine efficacy of steroidal and non-steroidal anti-inflammatory drugs as well as opiates and novel therapeutics.
Morphine (3 mg/kg) has analgesic effects in a formalin paw test in C3H mice, as determined by descriptive behavioral observations that provide an overall behavioral score. Morphine also significantly attenuates time spent licking the injected paw in both acute- and late-phase.
Pretreatment with the NSAID naproxen (30 mg/kg) decreases mechanical hyperalgesia induced by an intraplantar injection of carrageenan.
Pretreatment with the morphine increased paw withdrawal threshold as assessed by Von Frey Filaments in carrageenan-injected mice.