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Endocrine System Rare: hyperthyroid, hypothyroid, goiter, hypoestrogen, ovarian failure, epididymitis, swollen testicle, cushingoid appearance. Hematologic and Lymphatic System Text Continues Below
Frequent: purpura most often described as bruises resulting from physical trauma; Infrequent: anemia, thrombocytopenia, lymphadenopathy; Rare: WBC count increased, lymphocytosis, non-Hodgkin's lymphoma, bleeding time increased. Musculoskeletal System Frequent: arthralgia; Infrequent: tendinitis, arthritis, joint stiffness, joint swelling, positive Romberg test; Rare: costochondritis, osteoporosis, bursitis, contracture. Nervous System Frequent: vertigo, hyperkinesia, paresthesia, decreased or absent reflexes, increased reflexes, anxiety, hostility; Infrequent: CNS tumors, syncope, dreaming abnormal, aphasia, hypesthesia, intracranial hemorrhage, hypotonia, dysesthesia, paresis, dystonia, hemiplegia, facial paralysis, stupor, cerebellar dysfunction, positive Babinski sign, decreased
position sense, subdural hematoma, apathy, hallucination, decrease or loss of libido, agitation, paranoia, depersonalization, euphoria, feeling high, doped-up sensation, suicidal, psychosis;
Rare: choreoathetosis, orofacial dyskinesia, encephalopathy, nerve palsy, personality disorder, increased libido, subdued temperament, apraxia, fine motor control disorder, meningismus, local myoclonus, hyperesthesia, hypokinesia, mania, neurosis, hysteria, antisocial reaction, suicide gesture. Respiratory System Frequent: pneumonia; Infrequent: epistaxis, dyspnea, apnea; Rare: mucositis, aspiration pneumonia, hyperventilation, hiccup, laryngitis, nasal obstruction, snoring, bronchospasm, hypoventilation, lung edema. Dermatological Infrequent: alopecia, eczema, dry skin, increased sweating, urticaria, hirsutism, seborrhea, cyst, herpes simplex; Rare: herpes zoster, skin discolor, skin papules, photosensitive reaction, leg ulcer, scalp seborrhea, psoriasis, desquamation, maceration, skin nodules, subcutaneous nodule, melanosis, skin necrosis, local swelling. Urogenital System Infrequent: hematuria, dysuria, urination frequency, cystitis, urinary retention, urinary incontinence, vaginal hemorrhage, amenorrhea, dysmenorrhea, menorrhagia, breast cancer, unable to climax, ejaculation abnormal; Rare: kidney pain, leukorrhea, pruritus genital, renal stone, acute renal failure, anuria, glycosuria, nephrosis, nocturia, pyuria, urination urgency, vaginal pain, breast pain, testicle pain. Special Senses Frequent: abnormal vision; Infrequent: cataract, conjunctivitis, eyes dry, eye pain, visual field defect, photophobia, bilateral or unilateral ptosis, eye hemorrhage, hordeolum, hearing loss, earache, tinnitus, inner ear infection, otitis, taste loss, unusual taste, eye twitching, ear fullness; Rare: eye itching, abnormal accommodation, perforated ear drum, sensitivity to noise, eye focusing problem, watery eyes, retinopathy, glaucoma, iritis, corneal disorders, lacrimal dysfunction, degenerative eye changes, blindness, retinal degeneration, miosis, chorioretinitis, strabismus, eustachian tube dysfunction, labyrinthitis, otitis externa, odd smell. Clinical trials in Pediatric Patients With Epilepsy Adverse events occurring during epilepsy clinical trials in 449 pediatric patients 3 to 12 years of age treated with gabapentin that were not reported in adjunctive trials in adults are: Body as a Whole dehydration, infectious mononucleosis Digestive System hepatitis Hemic and Lymphatic System coagulation defect Nervous System aura disappeared, occipital neuralgia Psychobiologic Function sleepwalking Respiratory System pseudocroup, hoarseness Clinical Trials in Adults With Neuropathic Pain of Various Etiologies
Safety information was obtained in 1173 patients during double-blind and open-label clinical trials including neuropathic pain conditions for which efficacy has not been demonstrated. Adverse events reported by investigators were grouped into standardized categories using modified COSTART IV terminology. Listed below are all reported events except those already listed in Table 2 and those not reasonably associated with the use of the drug. Events are further classified within body system categories and enumerated in order of decreasing frequency using the following definitions: frequent adverse events are defined as those occurring in at least 1/ 100 patients; infrequent adverse events are those occurring in 1/ 100 to 1/ 1000 patients; rare events are those occurring in fewer than 1/ 1000 patients. Body as a Whole Infrequent: chest pain, cellulitis, malaise, neck pain, face edema, allergic reaction, abscess, chills, chills and fever, mucous membrane disorder; Rare: body odor, cyst, fever, hernia, abnormal BUN value, lump in neck, pelvic pain, sepsis, viral infection. Cardiovascular System Infrequent: hypertension, syncope, palpitation, migraine, hypotension, peripheral vascular disorder, cardiovascular disorder, cerebrovascular accident, congestive heart failure, myocardial infarction, vasodilatation; Rare: angina pectoris, heart failure, increased capillary fragility, phlebitis, thrombophlebitis, varicose vein. Digestive System Infrequent: gastroenteritis, increased appetite, gastrointestinal disorder, oral moniliasis, gastritis, tongue disorder, thirst, tooth disorder, abnormal stools, anorexia, liver function tests abnormal, periodontal abscess; Rare: cholecystitis, cholelithiasis, duodenal ulcer, fecal incontinence, gamma glutamyl transpeptidase increased, gingivitis, intestinal obstruction, intestinal ulcer, melena, mouth ulceration, rectal disorder, rectal hemorrhage, stomatitis. Endocrine System Infrequent: diabetes mellitus. Hemic and Lymphatic System Infrequent: ecchymosis, anemia; Rare: lymphadenopathy, lymphoma-like reaction, prothrombin decreased. Metabolic and Nutritional Infrequent: edema, gout, hypoglycemia, weight loss; Rare: alkaline phosphatase increased, diabetic ketoacidosis, lactic dehydrogenase increased. Musculoskeletal Infrequent: arthritis, arthralgia, myalgia, arthrosis, leg cramps, myasthenia; Rare: shin bone pain, joint disorder, tendon disorder.
Nervous System: Frequent: confusion, depression; Infrequent: vertigo, nervousness, paresthesia, insomnia, neuropathy, libido decreased, anxiety, depersonalization, reflexes decreased, speech disorder, abnormal dreams, dysarthria, emotional lability, nystagmus, stupor, circumoral paresthesia, euphoria, hyperesthesia, hypokinesia; Rare: agitation, hypertonia, libido increased, movement disorder, myoclonus, vestibular disorder. Respiratory System Infrequent: cough increased, bronchitis, rhinitis, sinusitis, pneumonia, asthma, lung disorder, epistaxis; Rare: hemoptysis, voice alteration. Skin and Appendages Infrequent: pruritus, skin ulcer, dry skin, herpes zoster, skin disorder, fungal dermatitis, furunculosis, herpes simplex, psoriasis, sweating, urticaria, vesiculobullous rash; Rare: acne, hair disorder, maculopapular rash, nail disorder, skin carcinoma, skin discoloration, skin hypertrophy. Special Senses Infrequent: abnormal vision, ear pain, eye disorder, taste perversion, deafness; Rare: conjunctival hyperemia, diabetic retinopathy, eye pain, fundi with microhemorrhage, retinal vein thrombosis, taste loss. Urogenital System Infrequent: urinary tract infection, dysuria, impotence, urinary incontinence, vaginal moniliasis, breast pain, menstrual disorder, polyuria, urinary retention; Rare: cystitis, ejaculation abnormal, swollen penis, gynecomastia, nocturia, pyelonephritis, swollen scrotum, urinary frequency, urinary urgency, urine abnormality. Postmarketing and Other Experience
In addition to the adverse experiences reported during clinical testing of Neurontin ® , the following adverse experiences have been reported in patients receiving marketed Neurontin ® . These adverse experiences have not been listed above and data are insufficient to support an estimate of their incidence or to establish causation. The listing is alphabetized: angioedema, blood glucose fluctuation, erythema multiforme, elevated liver function tests, fever, hyponatremia, jaundice, movement disorder such as dyskinesia, Stevens-Johnson syndrome. Adverse events following the abrupt discontinuation of gabapentin have also been reported. The most frequently reported events were anxiety, insomnia, nausea, pain and sweating. Drug Interactions In vitro studies were conducted to investigate the potential of gabapentin to inhibit the major cytochrome P450 enzymes (CYP1A2, CYP2A6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4) that mediate drug and xenobiotic metabolism using isoform selective marker substrates and human liver microsomal preparations. Only at the highest concentration tested (171 µ g/ mL; 1 mM) was a slight degree of inhibition (14%-30%) of isoform CYP2A6 observed. No inhibition of any of the other isoforms tested was observed at gabapentin concentrations up to 171 µ g/ mL (approximately 15 times the Cmax at 3600 mg/ day). Gabapentin is not appreciably metabolized nor does it interfere with the metabolism of commonly coadministered antiepileptic drugs. The drug interaction data described in this section were obtained from studies involving healthy adults and adult patients with epilepsy.
Phenytoin: In a single (400 mg) and multiple dose (400 mg TID) study of Neurontin ® in epileptic patients (N= 8) maintained on phenytoin monotherapy for at least 2 months, gabapentin had no effect on the steady-state trough plasma concentrations of phenytoin and phenytoin had no effect on gabapentin pharmacokinetics. Carbamazepine: Steady-state trough plasma carbamazepine and carbamazepine 10, 11 epoxide concentrations were not affected by concomitant gabapentin (400 mg TID; N= 12) administration. Likewise, gabapentin pharmacokinetics were unaltered by carbamazepine administration. Valproic Acid: The mean steady-state trough serum valproic acid concentrations prior to and during concomitant gabapentin administration (400 mg TID; N= 17) were not different and neither were gabapentin pharmacokinetic parameters affected by valproic acid. Phenobarbital: Estimates of steady-state pharmacokinetic parameters for phenobarbital or gabapentin (300 mg TID; N= 12) are identical whether the drugs are administered alone or together. Naproxen: Coadministration (N= 18) of naproxen sodium capsules (250 mg) with Neurontin ® (125 mg) appears to increase the amount of gabapentin absorbed by 12% to 15%. Gabapentin had no effect on naproxen pharmacokinetic parameters. These doses are lower than the therapeutic doses for both drugs. The magnitude of interaction within the recommended dose ranges of either drug is not known. Hydrocodone: Coadministration of Neurontin ® (125 to 500 mg; N= 48) decreases hydrocodone (10 mg; N= 50) Cmax and AUC values in a dose-dependent manner relative to administration of hydrocodone alone; Cmax and AUC values are 3% to 4% lower, respectively, after administration of 125 mg Neurontin ® and 21% to 22% lower, respectively, after administration of 500 mg Neurontin ® . The mechanism for this interaction is unknown. Hydrocodone increases gabapentin AUC values by 14%. The magnitude of interaction at other doses is not known. Morphine: A literature article reported that when a 60-mg controlled-release morphine capsule was administered 2 hours prior to a 600-mg Neurontin ® capsule (N= 12), mean gabapentin AUC increased by 44% compared to gabapentin administered without morphine (see PRECAUTIONS). Morphine pharmacokinetic parameter values were not affected by administration of Neurontin ® 2 hours after morphine. The magnitude of interaction at other doses is not known. Cimetidine: In the presence of cimetidine at 300 mg QID (N= 12) the mean apparent oral clearance of gabapentin fell by 14% and creatinine clearance fell by 10%. Thus cimetidine appeared to alter the renal excretion of both gabapentin and creatinine, an endogenous marker of renal function. This small decrease in excretion of gabapentin by cimetidine is not expected to be of clinical importance. The effect of gabapentin on cimetidine was not evaluated. Oral Contraceptive: Based on AUC and half-life, multiple-dose pharmacokinetic profiles of norethindrone and ethinyl estradiol following administration of tablets containing 2.5 mg of norethindrone acetate and 50 mcg of ethinyl estradiol were similar with and without coadministration of gabapentin (400 mg TID; N= 13). The Cmax of norethindrone was 13% higher when it was coadministered with gabapentin; this interaction is not expected to be of clinical importance. Antacid (Maalox ® ): Maalox reduced the bioavailability of gabapentin (N= 16) by about 20%. This decrease in bioavailability was about 5% when gabapentin was administered 2 hours after Maalox. It is recommended that gabapentin be taken at least 2 hours following Maalox administration. Effect of Probenecid: Probenecid is a blocker of renal tubular secretion. Gabapentin pharmacokinetic parameters without and with probenecid were comparable. This indicates that gabapentin does not undergo renal tubular secretion by the pathway that is blocked by probenecid. Drug/ Laboratory Tests Interactions
Because false positive readings were reported with the Ames N-Multistix SG ® dipstick test for urinary protein when gabapentin was added to other antiepileptic drugs, the more specific sulfosalicylic acid precipitation procedure is recommended to determine the presence of urine protein. Page: << Prev | 1 | 2 | 3 | 4 | 5
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