Gabapentin is an anticonvulsant GABA analog.

It is indicated for the treatment of the following disorders:

• Symptomatic treatment of postherpetic neuralgia in adults.
• Simple partial seizures or focal seizures with secondary generalisation in adults and children older than three years of age are treated with this medication.
• 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:

• One daily oral dose of 300 mg. Updating the dosage every other day will bring it to a daily maximum of 600 mg. 600 mg three times each day.

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:
• On days 1 through 3, take oral, immediate-release tablets containing 100 to 400 mg three times per day. On day 4, take 300 to 400 mg twice per day, and on day 5 stop.
• Give an extra 100 mg as a single dose up to three times per day if breakthrough symptoms develop.

For chronic unexplained cough:

• Depending on the reaction and tolerance, 300 mg orally once daily up to 900 mg twice daily. (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 normal dosage ranges from 100 to 300 mg once to three times each day. The dosage can be raised up to 1.2 grammes three times per day.
• The target dose for the extended-release version of gabapentin ranges from 300 mg at bedtime to 900–3.6 grammes once daily.

Dose of gabapentin in Postherpetic neuralgia:

Immediate-release oral tablets:

• Start with 300 mg once daily for the first day, then 300 mg twice daily for the second day, and 300 mg three times daily for the third day. If necessary, the dose may be raised to 1.8 - 3.6 grammes administered in divided doses each day.

Extended-release oral tablets:

• Begin by taking 300 mg of gabapentin once daily. Up till 900 mg per day, increase the dosage by 300 mg each day.

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

For the treatment of postoperative pain:

• It ought to be used in conjunction with other therapies. It should be administered in a single dose ranging from 300 mg to 1200 mg one to two hours before surgery or right thereafter.

For chronic refractory body itching or pruritus:

• 300 mg of gabapentin divided into 1 to 3 doses is the typical dosage. Up to 1.8 grammes of the dose can be taken every day. Patients with cancer may need high doses to treat pruritis.
• Patients with chronic renal failure may be given 100 mg of pruritis after dialysis. After dialysis, the dosage can be increased to 300 mg.

Restless legs syndrome:

• 2 hours before game time, take 100 to 300 mg every day. To 2.4 grammes per day, the dose may be raised at weekly intervals.
• If the daily dose is more than 600 mg, one-third should be administered around midday, and the final two-thirds should be administered before bedtime.

Partial (focal) Seizures:

• At first, 300 mg three times a day. Upping the dosage to 3.6 g/day is the maximum. The typical dosage is 300–600 mg three times a day.

Social anxiety disorder:

• Those with social anxiety disorders who don't respond to first-line therapy should take gabapentin.
• A dosage of 300 mg twice daily up to 3.6 gms per day in three divided doses should be used.

Vasomotor symptoms associated with menopause:

• 2.4 g is the daily maximum and is determined on the response and tolerance. 300 to 400 mg daily at bedtime.
• A 600 mg dose of the extended-release medication may be administered before night. If a dosage greater than 600 mg is advised, a third should be administered in the morning and a third 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 Children

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 with a dose at bedtime of 5 mg/kg/dose up to 300 mg. On day 2, double the dosage in two evenly spaced doses. On day three, increase the dosage to three times each day.
  • The American Pain Society (APS) suggests starting with a lower dose of 2 mg/kg/day while taking analgesics at the same time. The typical dosage is divided into three doses of 8 to 35 mg/kg/day.

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 compare the advantages and disadvantages. Pregnant women should not use gabapentin.

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: