Pharmacokinetics of propentofylline and the quantitation of its metabolite hydroxypropentofylline in human volunteers

Chronic administration of the methylxanthine propentofylline impairs reinstatement to cocaine by a GLT-1-dependent mechanism

In recent years, interactions between neurons and glia have been evaluated as mediators of neuropsychiatric diseases, including drug addiction. In particular, compounds that increase expression of the astroglial glutamate transporter GLT-1 (N-acetylcysteine and ceftriaxone) can decrease measures of drug seeking. However, it is unknown whether the compounds that influence broad measures of glial physiology can influence behavioral measures of drug relapse, nor is it clear whether the upregulated GLT-1 is functionally important for suppressing of drug seeking. To address these questions, we sought to determine whether the glial modulator and neuroprotective agent propentofylline (PPF) modifies drug seeking in rats using a reinstatement model of cocaine relapse. We found that 7 days of chronic (but not acute) administration of PPF significantly decreased both cue- and cocaine-induced reinstatement of cocaine seeking. We next determined whether the effect of systemic PPF on reinstatement depended upon its ability to restore expression of GLT-1 in the nucleus accumbens. PPF restored the cocaine-induced decrease in GLT-1 in the accumbens core; then, using an antisense strategy against glutamate transporter GLT-1, we found that restored transporter expression was necessary for PPF to inhibit cue-primed cocaine seeking. These findings indicate that modulating glial physiology with atypical xanthine derivatives like PPF is a potential avenue for developing new medications for cocaine abuse, and support the hypothesis that neuron-glial interactions contribute to mechanisms of psychostimulant addiction, particularly via expression and function of astroglial glutamate transporters.

Systemic administration of propentofylline does not attenuate morphine tolerance in non-injured rodents

Propentofylline is a phosphodiesterase inhibitor that has been shown to attenuate the onset of morphine tolerance when administered intrathecally to rats. The present studies examined whether systemic administration could be effective in attenuating morphine tolerance in non-injured rodents using a similar dosing paradigm. Propentofylline at 10, 30, or 50 mg/kg, administered intraperitoneally once daily for 5 days, was unable to attenuate morphine tolerance established by twice daily administration of 10 mg/kg morphine. These results suggest that direct delivery of propentofylline to the central nervous system (CNS) may be required in order to attenuate morphine tolerance.

Alzheimer's disease and the basal forebrain cholinergic system: relations to beta-amyloid peptides, cognition, and treatment strategies

Alzheimer's disease (AD) is the most common form of degenerative dementia and is characterized by progressive impairment in cognitive function during mid- to late-adult life. Brains from AD patients show several distinct neuropathological features, including extracellular beta-amyloid-containing plaques, intracellular neurofibrillary tangles composed of abnormally phosphorylated tau, and degeneration of cholinergic neurons of the basal forebrain. In this review, we will present evidence implicating involvement of the basal forebrain cholinergic system in AD pathogenesis and its accompanying cognitive deficits. We will initially discuss recent results indicating a link between cholinergic mechanisms and the pathogenic events that characterize AD, notably amyloid-beta peptides. Following this, animal models of dementia will be discussed in light of the relationship between basal forebrain cholinergic hypofunction and cognitive impairments in AD. Finally, past, present, and future treatment strategies aimed at alleviating the cognitive symptomatology of AD by improving basal forebrain cholinergic function will be addressed.

Mild cognitive impairment: emerging therapeutics

OBJECTIVE

To present a general overview of the etiology, definition, and prevalence of mild cognitive impairment (MCI), as well as outline possible treatment strategies.

DATA SOURCES

A MEDLINE search was conducted for relevant references generated from 1990 to 2000 concerning MCI, mild to moderate Alzheimer disease (AD), and therapeutic strategies. Several books were also used in the compilation of data for this review, as well as the authors' experience in designing and conducting MCI trials.

DATA EXTRACTION

All of the references listed were assessed, and all relevant information was included in this review.

DATA SYNTHESIS

Forgetful individuals most likely to develop AD have a condition known as MCI previous to their development of dementia. This condition is hallmarked by memory impairment that is abnormal for the individual's age and educational level. While not all individuals with MCI develop AD, it is apparent that the condition can serve as a potential marker for early onset of AD.

CONCLUSIONS

As many clinicians can attest, occasional forgetfulness is a common aspect of the aging process. Eventually, however, a large portion of forgetful individuals, especially those with MCI, will be diagnosed with AD or some other form of dementia. Indeed, many researchers have suggested that MCI should be regarded as incipient AD and that these individuals would benefit from drug therapy. Thus, MCI screening may be beneficial in terms of both early AD intervention and perhaps even AD prevention.

Effect of propentofylline (HWA 285) on focal ischemia in rats: effect of treatment and posttreatment duration on infarct size

BACKGROUND AND PUROSEe: in this study we tested the potentially neuroprotective properties of propentofylline in a model of focal ischemia with long-term, repeated treatment.

METHODS

37 male Wistar rats (280-300 g) underwent permanent occlusion of the middle cerebral artery (MCA). Infusion was started 30 min after occlusion of the MCA over a period of 2 h with a dosage of 0.01 mg/kg body weight. Immediately after the termination of infusion repetitive intraperitoneal injections were started. Animals were assigned to four groups: continuous treatment for a period of 12 h with 24-h survival (group A, n=9) or 48-h survival (group B, n=10), continuous treatment for a period of 48 h with 48-h survival (group C, n=9) and placebo (group D, n=9). Infarct size was calculated from brain slices stained with 2,3,5-triphenyltetrazolium chloride.

RESULTS

the infarct size was significantly reduced in group C (treatment for 48 h) (163.9+/-30.5 mm(3)) compared to the placebo group (297.4+/-17. 7 mm(3)). No effect on infarct size was observed in group A (196. 8+/-37.3 mm(3)) and group B (239.6+/-42.9 mm(3)) compared to placebo.

CONCLUSION

continuous i.p. injections of propentofylline over a period of 48 h significantly reduces infarct size in an animal model of focal cerebral ischemia. With shorter periods of continuous administration of the drug and delayed postmortem analysis, reductions in the infarct size did not reach a level of significance. These data show the importance of continuous long-term administration after ischemic stroke in clinical trials to achieve the beneficial effects of neuroprotection by propentofylline.