Piracetam

Absorption

Piracetam displays a linear and time-dependent pharmacokinetic properties with low intersubject variability over a large range of doses. Piracetam is rapidly and extensively absorbed following oral administration with the peak plasma concentration is reached within 1 hour after dosing in fasted subjects. Following a single oral dose of 3.2 g piracetam, the peak plasma concentration (Cmax) was 84 μg/mL. Intake of food may decrease the Cmax by 17% and increase the time to reach Cmax (Tmax) from 1 to 1.5 hours. Tmax in the cerebrospinal fluid is achieved approximately 5 hours post-administration .
The absolute bioavailability of piracetam oral formulations is close to 100% and the steady state plasma concentrations are achieved within 3 days of dosing .

Toxicity

The cases of overdose with piracetam is rare. The highest reported overdose with piracetam was oral intake of 75g which was associated with diarrhea and abdominal pain; the signs were most likely related to the extreme high dose of sorbitol contained in the used formulation. In cases of acute, significant overdosage, stomach emptying by gastric lavage or induced emesis is recommended as there are no known antidotes for piracetam . Management for an overdose will most likely be symptomatic treatment and may include hemodialysis, where the extraction efficacy of the dialyser is 50 to 60% for the drug .
Oral LD50 in a mouse acute toxicity study was 2000 mg/kg .

Description

Piracetam is an unregistered cognition enhancer widely used to treat neurological disorders. It was sold as a dietary supplement until FDA ordered this practice to be discontinued in 2010. It remains available online and in some US stores. H. Morren reported the synthesis of piracetam in 1966. Earlier this year, D. Croker et al. reported?a method to monitor the crystallization of piracetam?to ensure that the desired stable polymorph is formed.

The Uses of Piracetam

Piracetam has been used to study crystal structure and physicochemical properties of six co-crystals of piracetam. It has also been used to study its in vitro antioxidant properties.

Background

Piracetam is a nootropic drug in the racetams group, with chemical name 2-oxo-1-pyrrolidine acetamide. It shares the same 2-oxo-pyrrolidone base structure with pyroglutamic acid and is a cyclic derivative of the neurotransmitter γ-aminobutyric acid (GABA). However its mechanism of action differ from that of endogenous GABA. Piracetam has neuroprotective and anticonvulsant properties and is reported to improve neural plasticity . Its efficacy is documented in cognitive disorders and dementia, vertigo, cortical myoclonus, dyslexia, and sickle cell anemia although the clinical application in these conditions is not yet established. Piracetam has effects on the vascular system by reducing erythrocyte adhesion to the vascular endothelium, hindering vasospasms and facilitating microcirculation .
Originally marketed by UCB Pharma in 1971, piracetam was the first nootropic drug to modulate cognitive function without causing sedation or stimulation . It is not approved for any medical or dietary use by the FDA. In the UK, piracetam is prescribed mainly for myoclonus, but is used off-label for other conditions such as learning difficulties in children, memory loss or other cognitive defects in the elderly, and sickle-cell vaso-occlusive crises . Evidence to support its use for many conditions is unclear.

Indications

Indicated in adult patients suffering from myoclonus of cortical origin, irrespective of aetiology, and should be used in combination with other anti-myoclonic therapies .

What are the applications of Application

Piracetam is a modulator of neurotransmitter-induced ion flux

Pharmacokinetics

Piracetam is known to mediate various pharmacodynamic actions:
Neuronal effects:
Piracetam modulates the cholinergic, serotonergic, noradrenergic, and glutamatergic neurotransmission although the drug does not display high affinity to any of the associated receptors (Ki >10μM). Instead, piracetam increases the density of postsynaptic receptors and/or restore the function of these receptors through stabilizing the membrane fluidity . In the forebrain of aging mice, the density of NMDA receptors was increased by approximately 20% following 14 days of piracetam treatment. Based on the findings of various animal and human studies, the cognitive processses including learning, memory, attention and consciousness were enhanced from piracetam therapy without inducing sedation and psychostimulant effects . Piracetam mediate neuroprotective effects against hypoxia-induced damage, intoxication, and electroconvulsive therapy .
In two studies involving alcohol-treated rats with evidences of withdrawal-related neuronal loss, piracetam was shown to reduce the extent of neuronal loss and increase the numbers of synapses in the hippocampus by up to 20% relative to alcohol-treated or alcohol-withdrawn rats . This suggests that piracetam is capable in promoting neuroplasticity when recoverable neural circuits are present . Although the mechanism of action is not fully understood, administration of piracetam prior to a convulsant stimulus reduces the seizure severity and enhances the anticonvulsant effectiveness of conventional antiepileptics such as carbamazepine and diazepam .
Vascular effects:
Piracetam is shown to increase the deformability of erythrocytes, reduce platelet aggregation in a dose-dependent manner, reduce the adhesion of erythrocytes to vascular endothelium and capillary vasospasm. In healthy volunteers, piracetam mediated a direct stimulant effect on prostacycline synthesis and reduced the plasma levels of fibrinogen and von Willebrand’s factors (VIII: C; VIII R: AG; VIII R: vW) by 30 to 40% . Potentiated microcirculation is thought to arise from a combination of effects on erythrocytes, blood vessels and blood coagulation .

Metabolism

As large proportion of total piracetam administered is excreted as unchanged drug, there is no known major metabolism of piracetam .