Sun City Center, FL, August 01, 2013 --(PR.com
)-- Gabapentin (Neurontin) and pregabalin (Lyrica) are two medications used to treat neuropathic pain and partial seizure. As pain-relieving medications, these two drugs do not belong to the opioid family. Gabapentin was developed as a GABA analogue, and intended to mimic the gamma-Aminobutyric acid (GABA) pharmacological actions. GABA is an inhibitory neurotransmitter and the binding of GABA to its receptors in the central nervous system can lead to an influx of chloride ion to the neurons and hyper polarization of pre- and postsynaptic membranes. Tranquilizers, like benzodiazepines, barbiturates and alcohol, exert their pharmacological actions by working on the GABA receptors and potentiating its neuroinhibitory effects. By mimicking the chemical structure of GABA, gabapentin was originally designed as an anticonvulsant. However, subsequent studies found that neither of the drugs bind to GABA receptors. Instead, their mechanism of action might rely on their binding to the alpha-2 delta subunit of the presynaptic voltage gated-calcium channels responsible for the inhibition of the calcium influx. Gabapentin is not metabolized in the body, while pregabalin undergoes minimal metabolism in the human liver. Both drugs are eliminated predominantly through the urinary route as an unchanged drug. Compared to gabapentin, pregabalin exhibits better pharmacokinetic properties, with oral bioavailability at 90%.
American Clinical Solutions currently provides testing services for gabapentin and pregabalin in urine and oral fluid samples. The detection windows of gabapentin and pregabalin are 1-4 days in urine and 1 day in oral fluid. The average concentrations of gabapentin and pregabalin in urine, based on an internal study from patients with known prescriptions, were 412.6 and 184.6 μg/ml, respectively. The data largely agreed with those reported by other studies. American Clinical Solutions study also supported the notion that gabapentin has been widely prescribed for pain management. Among 15178 urine samples analyzed in the internal study, gabapentin was detected in 2476 urine samples (16.3% prevalence). To put it into perspective, gabapentin was the fifth most commonly detected medication among patients under pain management. More strikingly, a further analysis of urine drug test results and patients’ prescriptions revealed that when it came to the drugs used inconsistently – that is, the drugs were detected in a patient’s urine sample but not listed in his/her prescription – gabapentin was the second most commonly detected drug with regard to inconsistent use, only preceded by marijuana. The use of pregabalin was less prevalent, with a detection rate of 4.5% in the urine samples. The higher prevalence of gabapentin detection may not only attest to its efficacy in the treatment of pain with neuropathic origins, but may also reflect the fact that it has been widely prescribed for other off-label uses. Gabapentin is not a controlled substance, while pregabalin is a Schedule V controlled substance. However, a previous study on impaired driving cases in Washington State indicated that gabapentin was one of the commonly encountered drugs with a capability to impair driving.
Cheng Fang, MD., PH D., DABT | email@example.com
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