Pregabalin (Lyrica)

A CNS active compound analog of the neurotransmitter gamma-aminobutyric acid (GABA).

An anticonvulsive agent with a analgesic mechanism of action that involves binding to the alpha-2-delta subunit of calcium channels in hyperexcited afferent neurons, which reduces the release of glutamate, norepinephrine, and substance P, reducing pain signals transmitted from the periphery to the brain.

Bioavailability is 90% or greater, with no protein binding, and neglible metabolism.

Half-life 5–6.5 hours

Excretion via kidneys.

An anticonvulsant drug used for neuropathic pain and as an adjunct therapy for partial seizures with or without secondary generalization in adults.

Effective for generalized anxiety disorder.

Can be used to treat epilepsy, post-herpetic neuralgia and diabetic peripheral neuropathy, and chronic pain from fibromyalgia and spinal cord injury.

Has a low potential for abuse, and a limited dependence liability if misused.

Classified as a Schedule V drug.

Available in 25, 50, 75, 100, 150, 200, 225, and 300 mg capsules, and an oral solution containing 20 mg/mL.

Maximum daily recommended dose is 600mg.

Approval for use in treating epilepsy, diabetic neuropathic pain, fibromyalgia, and post-herpetic neuralgia.

Approved for neuropathic pain and pain from fibromyalgia, but the evidence of its effect on pain from other conditions is lacking.

Treatment begins with low dose and is increased gradually.

Therapeutic effect appears after 1 week.

Tolerance does not develop, and it does not disrupt sleep patterns and produces less severe cognitive and psychomotor impairment of comparable agents.

Commonly associated with dizziness, and drowsiness.

May be associated with blurred vision, diplopia, increased appetite, euphoria, confusion, extremely vivid dreams, changes in libido, irritability, ataxia, attention changes, abnormal coordination, memory impairment, tremors, dysarthria, parasthesia, vertigo, dry mouth and constipation, vomiting and flatulence, erectile dysfunction, fatigue, peripheral edema, drunkenness, abnormal walking, and weight gain.

Infrequently associated with depression, lethargy, agitation, hallucinations, myoclonus, hypoaesthesia, hyperaesthesia, tachycardia, excessive salivation, sweating, flushing, rash, muscle cramp, myalgia, arthralgia, urinary incontinence, dysuria, thrombocytopenia, kidney calculus.

May cause withdrawal effects after long-term use if discontinued abruptly, and symptoms include restlessness, insomnia, and anxiety.

Dosage should be reduced gradually.

When prescribed for seizures, rapid discontinuation may increase the intensity of the seizures and possibly cause the seizures to reoccur.

The drug may accumulate in patients with renal insufficiency and patients may experience myoclonus.

Acute overdosage may be manifested by somnolence, tachycardia and hypertonicity.

Plasma concentrations of pregabalin may be measured to monitor therapy.

Pregabalin binds to the alpha2delta subunit of the voltage-dependent calcium channel in the central nervous system.

Decreases the release of neurotransmitters such as glutamate, noradrenaline, and substance P.

Increases neuronal GABA levels by producing a dose-dependent increase in glutamic acid decarboxylase activity.

Glutamic acid decarboxylase (GAD) is the enzyme that converts the excitatory neurotransmitter glutamate into the inhibitory GABA in a single step.

Potentiates benzodiazepines, barbiturates and other central nervous system depressants.

Rapidly absorbed when administered on an empty stomach, with peak plasma concentrations occurring within one hour.

Oral bioavailability is estimated to be greater than or equal to 90%.

Rate of absorption is decreased with food intake, but has no clinically significant effect on the extent of absorption.

Volume of distribution of pregabalin for an orally administered dose is approximately 0.56 L/kg and is not bound to plasma proteins.

Undergoes negligible metabolism.

Eliminated from the systemic circulation primarily by renal excretion as unchanged drug.

Administered twice a day.

Effective in alleviating hot flashes.

For diabetic neuropathy.

The anti-epileptic drugs gabapentin and pregabalin are ligands of the subunits of neuronal voltage gated calcium channels which reduce neuronal excitability.
Gabapentin and pregabalin are recommended for the treatment of neuropathic pain.
Pregabalin is effective in demonstrated in trials of pain from fibromyalgia.
Trials of in neuropathic pain conditions the number of patients needed to be treated to achieve 50% reduction was  7.7 for pregabalin and 7.2 patients for gabapentin.
A trial failed to show in improvement with its use with sciatica.


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