Gabapentin is an anticonvulsant GABA analog.

It is indicated for the treatment of the following disorders:

• Symptomatic treatment of postherpetic neuralgia in adults.
• For the treatment of simple partial seizures or focal seizures with secondary generalization in adults and children more than three years of age.
• For Alcoholism and alcohol withdrawal
• For chronic refractory cough
• Fibromyalgia
• Hiccups or singultus
• Neuropathic pains
• Pruritis or itching resistant to the first line therapy
• Restless legs syndrome
• Vasomotor symptoms of menopause, and
• Social anxiety disorder

Gabapentin Dose in Adults

For the management of moderate to severe Alcohol use disorder:

• 300 mg orally once daily. Increase the dose every other day to a maximum of 600 mg thrice daily.e of 600 mg 3 times daily.

Gabapentin for Alcohol withdrawal:

• The dose of gabapentin should be individualized based on the symptoms and rates of alcohol withdrawal. One double-blind study suggested the following regimen:
• Oral immediate-release tablets of 100 to 400 mg thrice daily on days 1 through 3, then 300 to 400 mg twice daily on day 4, and then discontinue.
• If breakthrough symptoms occur, give an additional 100 mg as a single dose up to three times a day.

For chronic unexplained cough:

• 300 mg orally once daily to a maximum of 900 mg twice daily based on the response and tolerability (Chest guidelines & expert panel report).
• The patient should be evaluated after six months to assess for further continuation of the medicine.

Gabapentin for Fibromyalgia (alternative treatment):

• Initiate at a dose of 100 mg at bed-time. Gradually increase the dose weekly to a maximum of 1.2 to 2.4 grams per day in divided doses based on the clinical response and tolerability.

Hiccups (singultus):

• 300 to 1.2 grams per day in three or four divided doses. Discontinue if hiccups subside. It may be used for the long term management of chronic persistent hiccups. Other drugs like omeprazole, metoclopramide, and baclofen may be used along with gabapentin.

Neuropathic pain:

• Gabapentin should be used in conjunction with other modalities of pain. Adequate treatment response requires a time period of at least two months before labeling treatment failure.
• The usual dose is 100 to 300 mg once daily to thrice daily. The dose may be increased to a maximum of 1.2 grams three times a day.
• The extended-release formulation of gabapentin may be administered at a dose of 300 mg at bed-time to a target dose of 900 - 3.6 grams once daily.

Dose of gabapentin in Postherpetic neuralgia:

Immediate-release oral tablets:

• Start with 300 mg once daily on day 1, then 300 mg twice daily on day 2, and 300 mg thrice daily on day 3. The dose may be increased to 1.8 - 3.6 grams per day in divided doses if needed.

Extended-release oral tablets:

• Start with gabapentin in a dose of 300 mg once daily. Increase the dose by 300 mg daily up to 900 mg daily.

(The efficacy of gabapentin in doses of more than 1.8 grams has not been established).

For the treatment of postoperative pain:

• It should be used as an adjunct to other treatments. It should be given in a dose of 300 mg to 1200 mg as a single dose 1 to 2 hours prior to surgery or immediately following the surgery.

For chronic refractory body itching or pruritus:

• The usual dose is 300 mg of gabapentin divided in 1 - 3 doses. The dose may be increased up to 1.8 grams per day. Pruritis in cancer patients may require high doses.
• Pruritis in patients with chronic renal failure may be prescribed 100 mg after dialysis. The dose may be increased to 300 mg after dialysis.

Restless legs syndrome:

• 100 to 300 mg daily 2 hours before bet-time. The dose may be increased at weekly intervals to 2.4 grams per day.
• If the total dose is greater than 600 mg per day, one-third should be given at mid-day and the remaining 2/3 rd should be given at bed-time.

Partial (focal) Seizures:

• 300 mg thrice daily initially. Increase the dose to a maximum of 3.6 g/day. The usual dose is 300 to 600 mg thrice daily.

Social anxiety disorder:

• Gabapentin should be used in patients with a social anxiety disorder who fail first-line therapy.
• It should be given at a dose of 300 mg twice daily to a maximum of 3.6 gms per day in 3 divided doses.

Vasomotor symptoms associated with menopause:

• 300 to 400 mg daily at bedtime to a maximum of 2.4 grams per day based on the response and tolerability.
• The extended-release formulation may be given at a dose of 600 mg at bed-time. If more than 600 mg is recommended, 1/3rd should be given in the morning and 2/3rd in the evening.

How to discontinue gabapentin therapy?

• Gabapentin should be tapered gradually over more than a week to reduce the risk of rebound symptoms, withdrawal symptoms like confusion, irritability, sweating, and palpitations, and reduce the risks of seizures (in patients with epilepsy).

Gabapentin Dose in Childrens

Partial Onset Seizures:

• Children 3 - 12 years:
  • Start at a dose of 10 - 15 mg/kg/day in three divided doses. Increase the dose over a period of 3 days to a maximum of 40 mg/kg/day in three divided doses.
• Children greater than 12 years of age and Adolescents:
  • Start at a dose of 300 mg thrice daily to a maximum of 1800 mg in three divided doses. Doses up to 3600 mg have been used and well tolerated.

Neuropathic pain:

• Adolescents:
  • Start at a dose of 5 mg/kg/dose up to 300 mg at bedtime. Double the dose on day 2 in two divided doses. Increase the dose to thrice daily on day three.
  • The American Pain society (APS) recommends initiating a lower dose of 2 mg/kg/day with concurrent analgesics. The usual dosage ranges between 8 - 35 mg/kg/day in three divided doses.

Pregnancy Risk Factor C

• Gabapentin crosses over the placenta.
• Although adverse effects were observed in animal studies and in animals, there are not many data from pregnant women in humans. 
• You should weigh the benefits and the risks. Gabapentin should be avoided in pregnant women.

Gabapentin is used in breastfeeding

• Gabapentin use during breastfeeding is not well documented. 
• Gabapentin is generally considered safe while breastfeeding.
• Monitoring infants for weight gain/weight loss, developmental milestones and drowsiness should be done.

Gabapentin Dose in Renal Disease:

Immediate release Gabapentin:

• CrCl 60 mL/minute (or more): 300 mg to 1200m thrice daily
• CrCl >30 - 59 mg/minute: 200 - 700 mg twice daily.
• CrCl >15 to29 mL/minute: 200-700 mg once daily
• CrCl 15 mg/minute: 100-300 mg once daily
• ESRD requiring hemodialysis. Give a supplementary dose of 125-350 mg after hemodialysis.

Extended-release

• CrCl 60mL/minute and more1800 mg daily
• CrCl >30 - 59 mL/minute600 mg to 1800mg once daily
• CrCl 30mL/minute for patients on hemodialysisNot recommended.

Gabapentin Dose in Liver Disease:

• Gabapentin is not metabolized by the liver.
• No adjustment in dose has been provided by the manufacturer.

How to Administer Gabapentin?

Release immediately:

• Gabapentin can be taken with or without meals.
• However, if you are concerned about side effects, it is best to take Gabapentin with meals. 
• To avoid side effects such as drowsiness, the first dose should be taken at night.

Extended-release

• Extended-release should be taken at night before bed. 
• It is important to swallow the capsules whole.
• It should be taken at least 2 hours after administration of magnesium-containing antibiotics or aluminium.
• You can divide the tablets into two halves. However, you should not take them after 28 days.

Common Side effects of Gabapentin:

• CNS effects: Drowsiness, dizziness, ataxia, and fatigue
• Infections: Viral infections

Uncommon side effects:

• Cardiac: Edema, hypertension, and vasodilation.
• CNS: aggression, abnormal thinking, gait disturbances, lethargy, impaired concentration, and status epilepticus.
• Endocrine: Weight gain and increased blood sugars.
• GIT: nausea, vomiting, dyspepsia, and diarrhea.
• Genitourinary: Infections and infertility.
• Musculoskeletal: Tremors, fatigue, joint pains, and back pain
• Eye: nystagmus, diplopia, and conjunctivitis
• Respiratory: Otitis, bronchitis, pharyngitis, and cough
• Miscellaneous: Fever, anorgasmia, impotence, decreased libido, DRESS syndrome, skin rash, steven johnson syndrome, rhabdomyolysis, jaundice, and raised liver enzymes.

Contraindications to Gabapentin:

• Gabapentin allergy or any other component of the formulation are contraindications to its use.

Warnings and Precautions

• Angioedema and Anaphylaxis can occur following the first dose, or anytime during treatment. You should stop immediately and seek medical advice.
• Gabapentin can cause dizziness, drowsiness, and mental impairments. Take caution when operating heavy machinery or driving.
• Gabapentin may cause DRESS syndrome. Multiorgan involvement, eosinophilia and other symptoms may all be signs of DRESS syndrome.
• School performance may be affected by psychiatric symptoms such as volatile behavior, aggressive attitude and hyperkinesia.
• Suicidal thoughts should be monitored closely
• Gabapentin should not be taken with sedative drugs such as benzodiazepines, alcohol, or narcotic painkillers.
• It is not a good idea to use the same extended-release or immediate-release formulations interchangeably. Extended-release formulations have not been shown to be effective.
• Studies on animals have revealed an increase in pancreatic adenocarcinoma.
• You should not abruptly stop taking the drug as you may experience withdrawal symptoms such as confusion, irritability and palpitations. The seizure threshold can be decreased.

Monitoring Parameters:

Monitor renal functions periodically. Also assess the patient for suicidal tendency, thoughts, depression and behavioral changes.

Mechanism of action of Gabapentin:

Gabapentin modulates the release of excitatory neurotransmitters that are involved in the perception of pain and seizure activity.

Absorption occurs in the small bowel

Protein binding of gabapentin is less than 3% and it is not metabolized.

Bioavailability is inversely proportional to the dose.

Half-life elimination is 4 to 7 hours

Time to peak plasma levels is 2 - 4 hours for the immediate-release drug and 8 hours for the extended-release.

International Brands of Gabapentin:

Brand Names: US

• Gralise
• Gralise Starter
• Neurontin

Brand Names: Canada

• ACT Gabapentin [DSC]
• AG-Gabapentin
• APO-Gabapentin
• Auro-Gabapentin
• BCI Gabapentin [DSC]
• BIO-Gabapentin
• DOM-Gabapentin
• GD-Gabapentin
• GLN-Gabapentin
• JAMP-Gabapentin
• Mar-Gabapentin
• MYLAN-Gabapentin [DSC]
• Neurontin
• PHL-Gabapentin [DSC]
• PMS-Gabapentin
• Priva-Gabapentin
• PRO-Gabapentin
• RAN-Gabapentin
• RIVA-Gabapentin
• TARO-Gabapentin
• TEVA-Gabapentin
• VAN-Gabapentin

International Brands:

• Alpentin
• Anatin
• Bapex
• Barontin
• Bineurox
• Blugat
• Calmpent
• Carbatin
• Conventin
• Die Li
• Dineurin
• Dineurol
• Engaba
• Epiven
• Epleptin
• Etoclon
• G-Pentin
• Gabadin
• Gabagamma
• Gabalept
• Gabamax
• Gabanet
• Gabantin
• Gabapen
• Gabapenin
• Gabaran
• Gabaron
• Gabasant
• Gabatin
• Gabator
• Gabatrex
• Gabavex
• Gabenil
• Gabictal
• Gabix
• Gabon
• Gabutin
• Gantin
• Gapatin
• Gapridol
• Gaptin
• Gaty
• Gonnaz
• Gordius
• Mirgy
• Nepatic
• Nepsy
• Neuleptol
• Neupentin
• Neuran
• Neuril
• Neurontin
• Neuropen
• Neuroplex
• Neurostil
• New-GABA
• Nopatic
• Nupentin
• Nurona
• Opipentin
• Pendine
• Pengatine
• Penral
• Pentalipsy
• Reinin
• Remaltin
• Rontin
• Sipentin
• Tebantin
• Volar
• Vultin
• Vultin 600

Gabapentin Brands in Pakistan: