Description

Simple

A medication used to treat Restless Legs Syndrome (RLS) and to treat pain associated with the shingles virus that persists even once the rash associated with the virus has healed (postherpetic neuralgia).

Clinical

A gabapentin prodrug used to treat Restless Legs Syndrome (RLS) and postherpetic neuralgia (PHN).

Overview

Gabapentin enacarbil is marketed under the name Horizant. It is a prodrug of gabapentin, and indicated in adults for the treatment of Restless Legs Syndrome (RLS) and postherpetic neuralgia (PHN).

Pharmacology

Indication

For the treatment of adult Restless Legs Syndrome (RLS) and postherpetic neuralgia (PHN).

Pharmacodynamic

Since gabapentin enacarbil is a prodrug of gabapentin, it's physiological effects are the same as gabapentin. Concerning PHN, gabapentin prevents allodynia and hyperalgesia.

Mechanism of action

Although the exact mechanism of action of gabapentin in RLS and PHN is unknown, it is presumed to involve the descending noradrenergic system, resulting in the activation of spinal alpha2-adrenergic receptors.

Absorption

Gabapentin enacarbil is absorbed in the intestines by active transport through the proton-linked monocarboxylate transporter, MCT-1.

Protein binding

Gabapentin plasma protein binding is less than 3%.

Volume of distribution

The volume of distribution is 76L.

Clearance

Renal clearance of gabapentin is 5 to 7 L/hr.

Half life

The elimination half-life of gabapentin is 5.1 to 6.0 hours.

Route of elimination

Gabapentin enacarbil is eliminated primarily in the urine (94%) and to a lesser extent in the feces (5%).

Toxicity

Most common adverse reactions are headache, dizziness, and somnolence.

Adverse Effects

Effect Regions Age Groups Incidences Evidence Type
Dizziness US
  • adult
  • Kind: experimental
    • Percent: 17-30%
  • Kind: placebo
    • Percent: 15%
  • Clinical Trial
    Somnolence US
    • adult
  • Kind: experimental
    • Percent: 20-27%
  • Kind: placebo
    • Percent: 6%
  • Clinical Trial
    Sedation US
    • adult
  • Kind: experimental
    • Percent: 20-27%
  • Kind: placebo
    • Percent: 6%
  • Clinical Trial
    Dizziness US
    • adult
  • Kind: experimental
    • Percent: 13-22%
  • Kind: placebo
    • Percent: 4%
  • Clinical Trial
    Headache US
    • adult
  • Kind: experimental
    • Percent: 12-15%
  • Kind: placebo
    • Percent: 11%
  • Clinical Trial
    Somnolence US
    • adult
  • Kind: experimental
    • Percent: 10-14%
  • Kind: placebo
    • Percent: 8%
  • Clinical Trial
    Asthenia US
    • adult
  • Kind: experimental
    • Percent: 4-10%
  • Kind: placebo
    • Percent: 1%
  • Clinical Trial
    Fatigue US
    • adult
  • Kind: experimental
    • Percent: 4-10%
  • Kind: placebo
    • Percent: 1%
  • Clinical Trial
    Headache US
    • adult
  • Kind: experimental
    • Percent: 7-10%
  • Kind: placebo
    • Percent: 9%
  • Clinical Trial
    Nausea US
    • adult
  • Kind: experimental
    • Percent: 4-9%
  • Kind: placebo
    • Percent: 5%
  • Clinical Trial
    Insomnia US
    • adult
  • Kind: experimental
    • Percent: 3-7%
  • Kind: placebo
    • Percent: 2%
  • Clinical Trial
    Peripheral Edema US
    • adult
  • Kind: experimental
    • Percent: 6-7%
  • Kind: placebo
    • Percent: 0%
  • Clinical Trial
    Fatigue US
    • adult
  • Kind: experimental
    • Percent: 6-7%
  • Kind: placebo
    • Percent: 4%
  • Clinical Trial
    Nausea US
    • adult
  • Kind: experimental
    • Percent: 6-7%
  • Kind: placebo
    • Percent: 5%
  • Clinical Trial
    Blurred vision US
    • adult
  • Kind: experimental
    • Percent: 2-5%
  • Kind: placebo
    • Percent: 0%
  • Clinical Trial
    Weight increased US
    • adult
  • Kind: experimental
    • Percent: 3-5%
  • Kind: placebo
    • Percent: 1%
  • Clinical Trial
    Irritability US
    • adult
  • Kind: experimental
    • Percent: 4%
  • Kind: placebo
    • Percent: 1%
  • Clinical Trial
    Dry Mouth US
    • adult
  • Kind: experimental
    • Percent: 3-4%
  • Kind: placebo
    • Percent: 2%
  • Clinical Trial
    Depression US
    • adult
  • Kind: experimental
    • Percent: 0-3%
  • Kind: placebo
    • Percent: <1%
  • Clinical Trial
    Vertigo US
    • adult
  • Kind: experimental
    • Percent: 1-3%
  • Kind: placebo
    • Percent: 0%
  • Clinical Trial
    Weight increased US
    • adult
  • Kind: experimental
    • Percent: 2-3%
  • Kind: placebo
    • Percent: 2%
  • Clinical Trial
    Peripheral Edema US
    • adult
  • Kind: experimental
    • Percent: 0-3%
  • Kind: placebo
    • Percent: 1%
  • Clinical Trial
    Feeling abnormal US
    • adult
  • Kind: experimental
    • Percent: 0-3%
  • Kind: placebo
    • Percent: <1%
  • Clinical Trial
    Flatulence US
    • adult
  • Kind: experimental
    • Percent: 2-3%
  • Kind: placebo
    • Percent: <1%
  • Clinical Trial
    Feeling drunk US
    • adult
  • Kind: experimental
    • Percent: 1-3%
  • Kind: placebo
    • Percent: 0%
  • Clinical Trial
    Vertigo US
    • adult
  • Kind: experimental
    • Percent: <2%
  • Clinical Trial
    Irritability US
    • adult
  • Kind: experimental
    • Percent: <2%
  • Clinical Trial
    Vertigo US
    • adult
  • Kind: experimental
    • Percent: ≥2%
  • Clinical Trial
    Irritability US
    • adult
  • Kind: experimental
    • Percent: ≥2%
  • Clinical Trial
    Confusional state US
    • adult
  • Kind: experimental
    • Percent: <2%
  • Clinical Trial
    Balance disorder US
    • adult
  • Kind: experimental
    • Percent: <2%
  • Clinical Trial
    Dry Mouth US
    • adult
  • Kind: experimental
    • Percent: <2%
  • Clinical Trial
    Depression US
    • adult
  • Kind: experimental
    • Percent: <2%
  • Clinical Trial
    Increased appetite US
    • adult
  • Kind: experimental
    • Percent: <2%
  • Clinical Trial
    Flatulence US
    • adult
  • Kind: experimental
    • Percent: <2%
  • Clinical Trial
    Lethargy US
    • adult
  • Kind: experimental
    • Percent: <2%
  • Clinical Trial
    Disorientation US
    • adult
  • Kind: experimental
    • Percent: <2%
  • Clinical Trial
    Blurred vision US
    • adult
  • Kind: experimental
    • Percent: <2%
  • Clinical Trial
    Balance disorder US
    • adult
  • Kind: experimental
    • Percent: <2%
  • Clinical Trial
    Libido decreased US
    • adult
  • Kind: experimental
    • Percent: 0-2%
  • Kind: placebo
    • Percent: <1%
  • Clinical Trial
    Increased appetite US
    • adult
  • Kind: experimental
    • Percent: 2%
  • Kind: placebo
    • Percent: <1%
  • Clinical Trial
    Flatulence US
    • adult
  • Kind: experimental
    • Percent: ≥2%
  • Clinical Trial
    Increased appetite US
    • adult
  • Kind: experimental
    • Percent: ≥2%
  • Clinical Trial
    Depression US
    • adult
  • Kind: experimental
    • Percent: ≥2%
  • Clinical Trial
    Dry Mouth US
    • adult
  • Kind: experimental
    • Percent: ≥2%
  • Clinical Trial
    Balance disorder US
    • adult
  • Kind: experimental
    • Percent: ≥2%
  • Clinical Trial
    Confusional state US
    • adult
  • Kind: experimental
    • Percent: ≥2%
  • Clinical Trial
    Elevated creatine kinase US
    Clinical Trial Post Marketing
    Gynecomastia US
    Clinical Trial Post Marketing
    Breast enlargement US
    Clinical Trial Post Marketing

    Contraindications

    • Hypersensitivity:
      • false
    • Regions: US

    Food Interactions

    Take with or without food.