Liposome-Encapsulated Oxymorphone Hydrochloride Provides Prolonged Relief of Postsurgical Visceral Pain in Rats

摘要

Adequatepaincontrolisnecessaryforoptimalpostsurgicalrecoveryandhumanetreatmentoflaboratoryandcompanionanimals.Opioiddrugsarecurrentlythemostpotentanalgesicagentsavailableinhumanandveterinarymedicine.Long-actingformulationsofopioiddrugsconferseveralimportantadvantagesoverstandardpharmaceuticalpreparations,especiallyforuseinanimals.Along-actingformulationofoxymorphonehydrochloridewasproducedbyencapsulationintoliposomes.Liposome-encapsulated(LE)oxymorphonewastestedinaratmodelofvisceralpostoperativepain.RatsweregivenonesubcutaneousinjectionofLEoxymorphone(1.2or1.6mg/kgofbodyweight)orstandardoxymorphone(0.3mg/kg)atthetimeofintestinaltransectionorresection.AsingleadministrationofLEoxymorphonehydrochloridewasaseffectiveforreliefofpostoperativepaininrats(P=0.18),asweremultiple(q4horq8h)injectionsof0.3mg/kgofthestandardpharmaceuticalpreparation.TheratsgivenLEoxymorphonepriortointestinalresectionalsohadsignificantlyhigherbodyweightatthreeandsevendaysaftersurgerythandidratsthatweregivenstandardoxymorphone.Inconclusion,LEoxymorphonewaseffectiveintreatingvisceralpainassociatedwithintestinalsurgeryinrats.Onthebasisofbodyweightgain,ratstreatedwithLEoxymorphonehadimprovedrecoveryoutcome,comparedwithratstreatedwithrepeatedinjectionsofstandardoxymorphone.