Gantin

Gantin - Precautions | Dosage | Effects

This article was medically reviewed by M.Pharm, Marko Tanaskovic on August 12, 2018. To read more about an author, click here.

Gantin is a medicine that is produced by Pfizer Australia Pty Ltd and contains an active substance called gabapentin. The mechanism of action of this drug is not fully known, although it is thought that Gantin reduces the secretion of excitatory neurotransmitters because it binds to the alpha-2-delta subunit of the voltage-dependent calcium channels in the brain.

In addition to anti-epileptic, Gantin also exhibits analgesic effect (relieves pain). Because of these effects, Gantin is used in the treatment of neuropathy and generalized and partial tonic-clonic seizures.

Precautions

Gantin is absolutely contraindicated in patients who are allergic to the active substance gabapentin.

Drug reaction with eosinophilia and systemic symptoms (DRESS) has been reported with Gantin use. DRESS is an adverse reaction that usually starts with fever, rash and enlargement of the lymph nodes. Afterwards, DRESS may cause complications, such as: hepatitis, nephritis and myocarditis. The mortality of patients who developed DRESS is as much as 10%. Therefore, patients should be aware that they must immediately inform their doctor if any of the symptoms of DRESS occur.

The FDA has issued a warning that anti-epileptic drugs, including Gantin, may cause suicidal thoughts. It is therefore recommended that patients and their families be aware of warning signs that may indicate the occurrence of suicidal thoughts and that they should report to the doctor immediately if they notice these signs. Warning signs of suicide include anxiety, excessive and inappropriate feelings of guilt, aggressive behavior or talking about suicide (or, for instance, google-ing about suicide).

An epidemiological study involving more than 100,000 patients demonstrated that Gantin reduces the risk of suicidality in psychiatric patients and has no effects in patients who have no psychiatric disorders. However, due to the warning issued by the FDA, caution is advised and monitoring for warning signs recommended.

Gantin is reported to cause acute pancreatitis. If you notice symptoms, such as: abdominal pain that can spread to the back and may worsen after meals, nausea, vomiting, fever and tachycardia, you should contact your doctor immediately.

An abrupt discontinuation of the Gantin may cause status epilepticus, which can endanger the patient's life. Never discontinue Gantin unless your doctor has advised you.

Patients who are using opioid analgesics must use Gantin very carefully, because taking these drugs concomitantly increases the risk of respiratory depression, which leads to difficulty breathing and coma. Always inform your doctor about all the medicines you are taking.

There is not much data on the use of Gantin in patients above the age of 65. Increased incidence of peripheral edema and chronic fatigue in these patients has been reported.

Rare cases of abuse and dependence have been reported. Patients who have a history of addiction or drug abuse must use Gantin with extra precautions.

Interactions

Clinically significant interactions have been reported when Gantin is administered concomitantly with opioid analgesics and sodium oxybate (used to treat narcolepsy), and concomitant administration with these drugs should be avoided.

Dosage

Gantin can be found in the form of capsules (at a dose of 300 mg and 400 mg) and in the form of tablets at a dose of 800 mg.

The initial dose in patients over 12 years of age in the treatment of epilepsy and neuropathy is 300 mg once a day on the first day of treatment, 600 mg a day on the second day of treatment and 900 mg a day on the third day of treatment. After that, the dose can be gradually increased until an adequate antiepileptic or analgesic effect is achieved.

It is not recommended to use doses greater than 1800 mg daily in the treatment of epilepsy in patients over 12 years of age.

It is not recommended to use doses greater than 3600 mg daily in the treatment of neuropathy in patients over 12 years of age.

In children under 12 years of age, the dose should be calculated based on body weight.

Gantin, Pregnancy and Breastfeeding

According to the FDA, Gantin is classified in pregnancy category C. This means that studies on animals have demonstrated Gantin's toxicity to the fetus, but there are no well-controlled studies on humans. For this reason, Gantin should be used during pregnancy only if your doctor considers that the benefit of using the medicine is greater than the risk.

Gantin is excreted in breast milk, and breastfeeding must be discontinued while you are taking this medicine.

Side Effects

Gantin can cause the following side effects:

  • DRESS, which can be manifested by the following symptoms:
    • Enlargement of the lymph nodes.
    • Fever.
    • Rash.
    • Swelling of the spleen.
    • Hepatitis.
    • Nephritis.
    • Myocarditis.
  • Reduction in the number of blood platelets and consequently easy bruising.
  • Reduction in the number of white blood cells.
  • Changed blood sugar levels in diabetics.
  • Dizziness.
  • Ataxia.
  • Hypoesthesia.
  • Paresthesia.
  • Speech disorder.
  • Insomnia.
  • Tremor.
  • Tinnitus.
  • Vertigo.
  • Bronchitis.
  • Pneumonia.
  • Pharyngitis.
  • Cough.
  • Hair loss.
  • Pain in the chest.
  • Visual disturbances.
  • Vasodilation.
  • Myoclonus.
  • Allergic reactions.

Tell your doctor if you are experiencing any side effects.

References

  1. FDA
  2. Aranda C, Costa M, Meireles P, et all. Dress syndrome, gabapentin (GB) and autografts. World Allergy Organ J. 2015. 8: 166.
  3. Ragucci MV, COhen JM. Gabapentin-induced hypersensitivity syndrome. Clin Neuropharmacol. 2001. 24(2): 103-105.
  4. Pereira A, Gitlin M, Gross R, et all. Suicidality associated with anti-epileptic drugs: implications for the treatment of neuropathic pain and fibromyalgia. Pain. 2013. 154(3): 345-349.
  5. Kaurich T. Drug-induced acute pancreatitis. Proc (Bayl Univ Med Cent.). 2008. 21(1): 77-81.

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