Stability and compatibility of morphine-clonidine admixtures in an implantable infusion system.

Nonopioid analgesics are often coadministered with intrathecal morphine to increase efficacy. The purpose of this study was to evaluate stability and compatibility of morphine-clonidine admixtures with an implantable infusion system that is commonly used to treat pain patients. Infusion systems were filled with admixture and maintained at 37 degrees C for 90 days. Samples were collected monthly. Drug concentrations were determined using stability-indicating, high-performance liquid chromatography. For compatibility testing, individual materials comprising the fluid pathway of the device were immersed in clonidine solution and stored at 37 degrees C for various periods through 64 weeks and mechanical performance evaluated. After 3 months of containment in the infusion system, morphine and clonidine concentrations remained at > or = 94% of the theoretical starting concentrations. All device materials retained acceptable mechanical performance following clonidine exposure. These results demonstrate that morphine and clonidine are stable when combined in aqueous solution maintained at body temperature in an implantable infusion system for at least 3 months.

Chronic, controlled GDNF infusion promotes structural and functional recovery in advanced parkinsonian monkeys.

The powerful trophic effects that glial cell line-derived neurotrophic factor (GDNF) exerts on midbrain dopamine neurones suggest its use in treating Parkinson's disease. However, some important questions remain about the possible therapeutic applications of GDNF. Here we demonstrate that the chronic infusion of 5 or 15 micro g/day GDNF into the lateral ventricle or the striatum, using programmable pumps, promotes restoration of the nigrostriatal dopaminergic system and significantly improves motor functions in rhesus monkeys with neural deficits modelling the terminal stages of Parkinson's disease. The functional improvements were associated with pronounced upregulation and regeneration of nigral dopamine neurones and their processes innervating the striatum. When compared with vehicle recipients, these functional improvements were associated with (i) >30% bilateral increase in nigral dopamine neurone cell size; (ii) >20% bilateral increase in the number of nigral cells expressing the dopamine marker tyrosine hydroxylase; (iii) >70 and >50% bilateral increase in dopamine metabolite levels in the striatum and the pallidum, respectively; (iv) 233 and 155% increase in dopamine levels in the periventricular striatal region and the globus pallidus, respectively, on the lesioned side; and (v) a five-fold increase in tyrosine hydroxylase-positive fibre density in the periventricular striatal region on the lesioned side. In addition, chronic GDNF treatment did not induce the side-effects generally associated with chronic administration of levodopa, the most widely used treatment for Parkinson's disease. Thus, the results suggest that the prolonged and controlled delivery of GDNF into the brain could be used to intervene in long-term neurodegenerative disease processes like Parkinson's disease. Additional studies are required to determine the potential differences between chronic, intraventricular and intraputamenal (or intranigral) delivery of GDNF to maximize the efficacy of infusion treatments.