Biodegradable microspheres loaded with an anti-Parkinson prodrug: an in vivo pharmacokinetic study.

During chronic treatment with L-dopa (LD), Parkinsonian patients often experience uncontrolled motor complications due to fluctuations of the plasmatic levels of LD that result in pulsatile dopaminergic stimulation. To overcome these plasmatic fluctuations, a novel prodrug of LD, L-dopa-α-lipoic acid (LD-LA), has been proposed as a tool for achieving continuous dopaminergic stimulation. Due to slower susceptibility toward enzymatic conversion by LD-degrading enzymes (such as catechol-O-methyltransferase and monoamine oxidase), the plasma half-life of this prodrug is longer than that of LD. Moreover, the higher lipophilicity of LD-LA over LD promotes its delivery to the CNS, where the resulting levels of dopamine (DA) are kept high for a longer time than after equimolar administration of LD. To further reduce fluctuations in plasma levels of LD, LD-LA has been entrapped into biodegradable polymeric microspheres to be used as a depot system with the aim to prevent prodrug degradation and to obtain a sustained release of the intact compound. In the present work, a formulation of LD-LA loaded microspheres (characterized for drug loading, size, morphology, thermal properties, and in vitro prodrug release) has been administered subcutaneously to rats, and the resulting levels of LD and DA in plasma and striatal tissue, respectively, have been monitored. A good correlation between the in vitro release kinetics and the time range during which the formulation alters the LD/DA tissue levels in vivo was observed, suggesting that the polymeric microsphere matrix protects the loaded prodrug from chemical and enzymatic degradation and controls its release. Interestingly, LD-LA microspheres provided sustained levels of DA neurotransmitter in the striatum nucleus for up to 4 days after a single administration. In conclusion, a polymeric microsphere formulation of LD-LA is an attractive medicine for treating Parkinson's disease (PD) symptoms, avoiding motor complications.

Ibuprofen and lipoic acid diamide as co-drug with neuroprotective activity: pharmacological properties and effects in beta-amyloid (1-40) infused Alzheimer's disease rat model.

Both oxidative stress and inflammation are elevated in brains of Alzheimer's disease patients, but their pathogenic significance still remains unclear. Current evidence support the hypothesis that non-steroidal anti-inflammatory drugs (NSAIDs) and antioxidant therapy might protect against the development of Alzheimer's disease, and ibuprofen has the strongest epidemiological support. In the present work our attention was focused on (R)-alpha-lipoic acid considered as a potential neuroprotective agent in Alzheimer's disease therapy. In particular, we investigated a new co-drug (1) obtained by joining (R)-alpha-lipoic acid and ibuprofen via a diamide bond, for evaluating its potential to antagonize the deleterious structural and cognitive effects of beta-amyloid (1-40) in an infused Alzheimer's disease rat model. Our results indicated that infusion of beta-amyloid (1-40) impairs memory performance through a progressive cognitive deterioration; however, ibuprofen and co-drug 1 seemed to protect against behavioural detriment induced by simultaneous administration of beta-amyloid (1-40) protein. The obtained data were supported by the histochemical findings of the present study: beta-amyloid protein was less expressed in 1-treated than in ibuprofen and (R)-alpha-lipoic acid alone-treated cerebral cortex. Taken together, the present findings suggest that co-drug 1 treatment may protect against the cognitive dysfunction induced by intracerebroventricular infusion of beta-amyloid (1-40) in rats. Thus, co-drug 1 could prove useful as a tool for controlling Alzheimer's disease-induced cerebral amyloid deposits and behavioural deterioration.