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Old 05-17-2002, 05:19 AM   #1
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Join Date: May 2002
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stanislava HB User
Question Why Neurontin(Gabapentin) for a broken arm?

Hello
My arm was broken very bad and there is something wrong with the radial nerv. I have problems with the sensitivity and movement of my fingers. The doctors gave me a prescription for Neurontin(Gabapentin). Why do I need a medicine for epileptics and psychiatric conditions?
Thanks
S-a

 
Old 05-17-2002, 08:29 AM   #2
Zafu
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Hi,

Neurontin is often used in small doses because it has a side effect of greatly reducing nerve pain. My Mother takes it for Diabetic Peripheral Neuropathy which is a nerve related disorder.....

Hope this helps

Zafu

 
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Old 05-17-2002, 08:47 AM   #3
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Join Date: Dec 2001
Posts: 808
Jaytor HB User
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Hi:

No idea why you would prescribed this med unless your doctor feels that your nerve injury can somehow be controlled this way. This drug seems to have many potentially serious side-effects. Below is a cut & paste of a pharmacology article on this drug.

Gabapentin Systemic

Common Names:
Another commonly used name is GBP .
Category: Anticonvulsant

Indications
Accepted Epilepsy (treatment adjunct) Gabapentin is indicated as an adjunct to other anticonvulsant medications (in the treatment of partial seizures with or without secondary generalization in adults and adolescents )1 with epilepsy. Gabapentin is also indicated as adjunctive therapy for the treatment of partial seizures in pediatric patients 3 years of age and older with epilepsy.1

Pharmacology/Pharmacokinetics
Physicochemical characteristics:
Chemical group -
Cyclohexane-acetic acid derivative. Structural analog to gamma-aminobutyric acid (GABA) .

Mechanism of action/Effect:
The mechanism of action is unknown. Gabapentin does not interact with GABA receptors , is not metabolized to a GABA agonist or to GABA , and does not inhibit GABA uptake or degradation. In rats, gabapentin interacts with a novel binding site on cortical neurons that may be associated with the L-system amino acid transporter of brain cell membranes.

Absorption:
Rapid. Gabapentin is absorbed in part by the L-amino acid transport system , which is a carrier-mediated , saturable transport system ;
as the dose increases, bioavailability decreases. Bioavailability ranges from approximately 60% for a 300-mg dose to approximately 35% for a 1600-mg dose.

Absorption is unaffected by food.

Distribution:
Volume of distribution (Vol D ) is approximately 50 to 60 L . Gabapentin penetrates the blood - brain barrier, yielding cerebrospinal fluid (CSF) concentrations approximately equal to 20% of corresponding steady-state plasma trough concentrations in patients with epilepsy . Brain tissue concentrations in one patient undergoing temporal lobectomy were approximately 80% of corresponding plasma concentrations.

Protein binding:
Very low (<5%).

Biotransformation:
Gabapentin is not metabolized.

Half-life:
Elimination
Normal renal function: 5 to 7 hours.

Impaired renal function (creatinine clearance <
30 mL/minute): 52 hours.

In hemodialysis: In 11 anuric patients, a single 400-mg oral dose of gabapentin had an elimination half-life of 132 hours on days when patients did not receive dialysis, and 3.8 hours during dialysis.

Time to peak concentration:
2 to 4 hours.

Therapeutic serum concentration
The therapeutic serum concentration range for gabapentin is not well defined. However, in one study it was noted that seizure frequency decreased significantly only in patients with gabapentin serum concentrations >
2 mg/L (11.7 micromoles/L). After receiving gabapentin 400 mg three times per day for one week, patients maintained on phenytoin had minimum gabapentin plasma concentrations of 2 to 4.8 mg/L (11.7 to 28 micromoles/L) and maximum gabapentin plasma concentrations of 3.6 to 8.6 mg/L (21 to 50.2 micromoles/L). Titration of dosage is based on clinical response.

Note:
Steady-state pharmacokinetics of gabapentin in patients with epilepsy were similar to those in healthy subjects .

Elimination:
Renal - Entire absorbed dose , as unchanged drug. Gabapentin clearance is directly proportional to creatinine clearance.

In dialysis - Gabapentin can be removed from plasma by hemodialysis.

Precautions to Consider
Carcinogenicity/Tumorigenicity
In two-year carcinogenicity studies, a statistically significant increase in the incidence of pancreatic acinar cell adenomas and carcinomas was found in male rats receiving doses of gabapentin that produced plasma concentrations 10 times higher than those seen in humans receiving 3600 mg per day. Tumors were noninvasive, did not metastasize, did not affect survival, and did not occur in female rats or in mice. The significance to humans is unknown.

Mutagenicity
No evidence of mutagenicity was found in appropriate and testing. Gabapentin was negative in the Ames test, and negative in the HGPRT forward mutation assay in Chinese hamster lung cells;
it did not produce significant increases in chromosomal aberrations in the Chinese hamster lung cell assay; it was negative in the chromosomal aberration assay and in the micronucleus test in Chinese hamster bone marrow.

Pregnancy/Reproduction
Fertility -
No adverse effect on fertility was seen in rats given up to 5 times an equivalent human dose of 3600 mg on a mg per square meter of body surface area (mg/m 2 ) basis.

Pregnancy -
Gabapentin should be used during pregnancy only if the benefit justifies the potential risk to the fetus.

Adequate and well-controlled studies have not been done in humans.

Gabapentin has been shown to be fetotoxic in rodents . Pregnant mice given 1 to 4 times an equivalent human dose of 3600 mg on a mg/m 2 basis during organogenesis produced offspring with delayed ossification of several bones in the skull, vertebrae, and limbs. Rats given approximately 1 to 5 times an equivalent human dose of 3600 mg on a mg/m 2 basis produced offspring with an increased incidence of hydroureter and hydronephrosis. In rabbits given <
¼ to 8 times an equivalent human dose of 3600 mg on a mg/m 2 basis, an increased incidence of postimplantation fetal loss occurred.

Breast-feeding
It is not known whether gabapentin is distributed into breast milk.

Pediatrics
Appropriate studies performed to date have not demonstrated pediatrics specific problems that would limit the usefulness of gabapentin in children ages 3 - 12.

Geriatrics
Plasma clearance of gabapentin is reduced in the elderly , probably due to age-related renal function decline. Dosage reduction based on creatinine clearance is recommended. Further dosage adjustments should be based on clinical response.

Drug interactions and/or related problems
The following drug interactions and/or related problems have been selected on the basis of their potential clinical significance (possible mechanism in parentheses where appropriate) - not necessarily inclusive ( » = major clinical significance):

Note:
Gabapentin does not induce or inhibit the hepatic mixed oxidase enzymes responsible for drug metabolism . Also, it does not interfere with the metabolism of commonly coadministered antiepileptic agents .

Combinations containing any of the following medications, depending on the amount present, may also interact with this medication.
Alcohol or Central nervous system (CNS) depression-producing medications, other (see Appendix II )
(increased CNS depression may occur)
»Antacids, especially aluminum- and magnesium-containing (antacid taken with or within 2 hours after gabapentin reduces gabapentin"s bioavailability by 20% ; gabapentin should be taken at least 2 hours after antacid )

Laboratory value alterations
The following have been selected on the basis of their potential clinical significance (possible effect in parentheses where appropriate) - not necessarily inclusive ( » = major clinical significance):

With diagnostic test results Dipstick tests for urinary protein (e.g., Ames N-Multistix SG, Chemstrip 3) (gabapentin causes a false positive result;
the sulfosalicylic acid precipitation procedure should be used to detect urinary protein in patients taking gabapentin )

With physiology/laboratory test values White blood cell counts (may be decreased)

Medical considerations/Contraindications
The medical considerations/contraindications included have been selected on the basis of their potential clinical significance (reasons given in parentheses where appropriate) - not necessarily inclusive ( » = major clinical significance).

Risk-benefit should be considered when the following medical problems exist »Renal function impairment
(elimination may be prolonged in patients not receiving hemodialysis, and shortened in patients during hemodialysis ; dosage adjustment based on creatinine clearance is recommended )
Sensitivity to gabapentin or any ingredients in the formulation

Side/Adverse Effects
The following side/adverse effects have been selected on the basis of their potential clinical significance (possible signs and symptoms in parentheses where appropriate) - not necessarily inclusive:

Note:
Adverse effects from gabapentin therapy are generally mild to moderate in severity, and tend to diminish with continued use .

Those indicating need for medical attention
Incidence more frequent Ataxia (clumsiness or unsteadiness) - may be dose-related nystagmus (continuous, uncontrolled, back-and-forth and/or rolling eye movements )
In pediatric patients 3 to 12 years of age Neuropsychiatric problems, including emotional lability (anxiety behavior problems crying false sense of well-being mental depression reacting too quickly, too emotionally, or overreacting rapidly changing moods) hostility (aggressive behavior suspiciousness or distrust ) hyperkinesia (hyperactivity or increase in body movements restlessness) and thought disorders (concentration problems and change in school performance)

Incidence less frequent Amnesia (loss of memory) depression, irritability, or other mood or mental changes

Incidence rare Leukopenia (usually asymptomatic rarely, fever or chills cough or hoarseness lower back or side pain painful or difficult urination)
Those indicating need for medical attention only if they continue or are bothersome

Incidence more frequent Dizziness fatigue (unusual tiredness or weakness) myalgia (muscle ache or pain) peripheral edema (swelling of hands, feet, or lower legs) somnolence (drowsiness) - may be dose-related tremor (trembling or shaking) vision abnormalities, including blurred vision and diplopia (double vision)

Incidence less frequent or rare Asthenia (weakness or loss of strength) back pain dryness of mouth or throat dysarthria (slurred speech) frequent urination gastrointestinal effects, including constipation , diarrhea , dyspepsia (indigestion) nausea , and vomiting headache hypotension (low blood pressure) impotence (decrease in sexual desire or ability) insomnia (trouble in sleeping) rhinitis (runny nose) tinnitus (noise in ears ) trouble in thinking twitching weight gain

Overdose
For more information on the management of overdose or unintentional ingestion, contact a Poison Control Center (see Poison Control Center Listing ).

Clinical effects of overdose
Note:
Some of the effects of gabapentin overdose may be similar to adverse effects seen at therapeutic doses;
they may be more severe, or several adverse effects may occur together. Saturation of the carrier-mediated absorption pathway at higher gabapentin doses may limit drug absorption at the time of overdose and subsequently reduce the toxicity from overdose .

The following effects have been selected on the basis of their potential clinical significance (possible signs and symptoms in parentheses where appropriate) - not necessarily inclusive:

Diarrhea diplopia (double vision) dysarthria (slurred speech) lethargy (sluggishness) somnolence (drowsiness)

Treatment of overdose
Note:
There is no specific antidote for gabapentin overdose.

Specific treatment - Hemodialysis (may be indicated by clinical state or in patients with significant renal impairment)

Supportive care - Patients in whom intentional overdose is confirmed or suspected should be referred for psychiatric consultation.

Patient Consultation
As an aid to patient consultation, refer to .

In providing consultation, consider emphasizing the following selected information ( » = major clinical significance):

Before using this medication
»Conditions affecting use, especially:
Sensitivity to gabapentin

Use in the elderly -
Elderly patients may excrete gabapentin more slowly;
dosage reduction based on creatinine clearance and dosage adjustment based on clinical response are recommended

Other medications, especially antacids

Other medical problems, especially renal function impairment

Proper use of this medication
Compliance with therapy;
not taking more or less medicine than prescribed;
not missing any doses

Importance of not exceeding 12-hour interval between any 2 doses while on 3-times-a-day dosing schedule

Importance of dissolving each dose as needed when a liquid dosage form is required;
not dissolving any doses to save for later use

Missed dose: Taking as soon as possible;
if less than 2 hours until next dose, taking missed dose immediately and taking next dose 1 to 2 hours later, then resuming regular dosing schedule;
not doubling doses

»Proper storage
Precautions while using this medication
Importance of regular visits to physician to check progress of therapy

Discussing alcohol use or use of other CNS depressants with physician

Possible blurred or double vision, dizziness, drowsiness, impairment of thinking or motor skills;
caution when driving or doing jobs requiring alertness

Possible false positive results with dipstick tests for urinary protein; using the sulfosalicylic acid precipitation procedure to determine presence of urinary protein

Not discontinuing gabapentin abruptly;
consulting physician about gradually reducing dosage

Side/adverse effects
Ataxia;
nystagmus;
amnesia;
depression, irritability, or other mood or mental changes;
leukopenia

General Dosing Information
Gabapentin dosage is titrated to clinical effect , not to plasma concentration.

Adverse effects are generally mild to moderate in severity, and tend to diminish with continued use of gabapentin.

Anticonvulsant medications should not be discontinued abruptly because of the possibility of increased seizure frequency. If gabapentin is to be discontinued, or if another anticonvulsant medication is to be added to the patient's therapy, the change should be made gradually, over a minimum period of one week, to avoid loss of seizure control.

Oral Dosage Forms GABAPENTIN CAPSULES
Usual adult and adolescent dose
Anticonvulsant

Oral, initially 300 mg three times a day . The dosage may be gradually increased based on clinical response. Dosages of 900 to 1800 mg per day are effective for most patients . However, dosages as high as 2400 to 3600 mg per day have been well tolerated.

Note:
Dosage may be increased more slowly to avoid CNS adverse effects.

When taking gabapentin three times a day, the maximum time between doses should not exceed twelve hours.

For patients with renal function impairment: See Usual geriatric dose .

For patients undergoing hemodialysis: Oral, 300 to 400 mg initially for patients who have never received gabapentin , then 200 to 300 mg following each four hours of hemodialysis.

Usual adult and adolescent prescribing limits
3600 mg per day.

Usual pediatric dose
Anticonvulsant

Children 3 years to 12 years - The starting dose should range from 10 to 15 mg per kg per day, divided into three doses. The effective dose should be reached by upward titration over a period of approximately 3 days.

Ages 5 years and older - The effective dose is 25 to 35 mg per kg per day given in divided doses (three times a day)
Ages 3 years and 4 years - The effective dose is 40 mg per kg per day given in divided doses (three times a day)

Children 12 years of age and over: See Usual adult and adolescent dose.

Usual geriatric dose
Anticonvulsant

Oral, initial dosage recommendations, based on creatinine clearance, are as follows. Dosage adjustments may be made based on clinical response.

Creatinine Clearance (mL per minute) Total Daily Dose (mg per day) Dosage Regimen (mg)
>
60 1200 400 three times a day
30 to 60 600 300 two times a day
15 to 30 300 300 once a day
<
15 150 300 once every other day

Strength(s) usually available
U.S. - 100 mg (Rx) Neurontin lactose 300 mg (Rx) Neurontin lactose 400 mg (Rx) Neurontin lactose
Canada - 100 mg (Rx) Neurontin lactose 300 mg (Rx) Neurontin lactose 400 mg (Rx) Neurontin lactose
Note:
Capsule shells may contain gelatin, titanium dioxide, silicon dioxide, sodium lauryl sulfate, yellow iron oxide, red iron oxide, and FD&
C Blue No. 2.

Packaging and storage:
Store below 40 ° C (104 ° F), preferably between 15 and 30 ° C (59 and 86 ° F), in a well-closed container, unless otherwise specified by manufacturer.

Preparation of dosage form:
For patients who cannot take oral solids - Individual doses may be dissolved in juice or sprinkled over soft foods, such as applesauce, immediately before use. However, gabapentin solutions degrade over time and should be freshly prepared and taken immediately after preparation.

Auxiliary labeling:
May cause blurred vision.
May cause dizziness.
May cause drowsiness. Alcohol may intensify this effect.
GABAPENTIN ORAL SOLUTION
Usual adult and adolescent dose
See Gabapentin Capsules

Usual adult and adolescent prescribing limits
See Gabapentin Capsules

Usual pediatric dose
See Gabapentin Capsules

Children 12 years of age and over: See Usual adult and adolescent dose.

Usual geriatric dose
See Gabapentin Capsules

Strength(s) usually available
U.S. - 50 mg per mL (Rx) Neurontin glycerin xylitol purified water artificial cool strawberry anise flavor
Canada -
Not commercially available.

Packaging and storage:
Store refrigerated, 2 ° - 8 ° C (36 ° -46 ° F)

Auxiliary labeling:
May cause blurred vision.
May cause dizziness.
May cause drowsiness. Alcohol may intensify this effect.
GABAPENTIN TABLETS
Usual adult and adolescent dose
See Gabapentin Capsules

Usual adult and adolescent prescribing limits
See Gabapentin Capsules

Usual pediatric dose
See Gabapentin Capsules

Children 12 years of age and over: See Usual adult and adolescent dose.

Usual geriatric dose
See Gabapentin Capsules

Strength(s) usually available
U.S. - 600 mg (Rx) Neurontin poloxamer 407 copolyvidonum cornstarch magnesium stearate hydroxypropyl cellulose talc candellila wax purified water synthetic black iron oxide pharmaceutical shellac pharmaceutical glaze propylene glycol ammonium hydroxide isopropyl alcohol n-butyl alcohol 800 mg (Rx) Neurontin poloxamer 407 copolyvidonum cornstarch magnesium stearate hydroxypropyl cellulose talc candellila wax purified water synthetic yellow iron oxide synthetic red iron oxide hydroxypropyl methylcellulose propylene glycol methanol isopropyl alcohol deionized water
Canada -
Not commercially available.

Packaging and storage:
Store at 25 ° C (77 ° F);
excursions permitted to 15 ° and 30 ° C (59 ° and 86 ° F)

Auxiliary labeling:
May cause blurred vision.
May cause dizziness.
May cause drowsiness. Alcohol may intensify this effect.


 
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