Tiagabine Hcl (tiagabine HCl)

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Tiagabine hydrochloride is administered orally with food. Food delays, but does not decrease the extent of tiagabine absorption. The initial tiagabine dosage is given once daily; following dosage increases after the initial period, the dosage should be administered in 2-4 divided doses daily.

Patients currently receiving or beginning therapy with tiagabine and/or any other anticonvulsant should be closely monitored for notable changes in behavior that could indicate the emergence or worsening of suicidal thoughts or behavior or depression. (See Suicidality Risk under Warnings/Precautions: Warnings, in Cautions.)

The manufacturer states that a therapeutic range of plasma tiagabine concentrations has not been established; however, because of the potential for altered tiagabine clearance during concurrent administration of hepatic microsomal enzyme-inducing or -inhibiting drugs, it may be useful to determine plasma tiagabine concentrations before and after changes are made to the patient's drug regimen.

Because of the possibility of increasing seizure frequency, anticonvulsant drugs, including tiagabine, should not be discontinued abruptly. (See Discontinuance of Therapy under Warnings/Precautions: Warnings, in Cautions.)

There is no enhanced messaging for this drug.

There are no contraindication interactions for this drug.

There are no severe interactions for this drug.

Moderate Interaction: Assess the risk to the patient and take action as needed.

Tiagabine/Selected Anticonvulsants; Barbiturates

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Barbiturates, carbamazepine, phenobarbital, phenytoin, and primidone may induce the metabolism of tiagabine by CYP3A4.(1)

CLINICAL EFFECTS: Concurrent use of barbiturates, carbamazepine, phenobarbital, phenytoin, or primidone with tiagabine may result in decreased levels and clinical effectiveness of tiagabine.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Patients receiving concurrent therapy with tiagabine and barbiturates, carbamazepine, phenobarbital, phenytoin, or primidone should be observed for decreased tiagabine levels and clinical effectiveness. The dose of tiagabine should be adjusted accordingly when coadministered with enzyme-inducing antiepileptic drugs. The US manufacturer of tiagabine provides dosing titration recommendations for tiagabine when used concurrently with enzyme-inducing antiepileptic drugs. In patients 12-18 years old, tiagabine should be initiated at 4 mg daily and increased by 4 mg weekly until clinical response is achieved, to a maximum of 32 mg/day. In adults, tiagabine should be initiated at 4 mg daily and increased by 4-8 mg weekly until clinical response is achieved, to a maximum of 56 mg/day. The dose of tiagabine may need to be adjusted if these agents are added to or removed from tiagabine therapy. It may be useful to obtain plasma levels of tiagabine before and after changes are made in the therapeutic regimen.(1)

DISCUSSION: Population pharmacokinetic studies have shown that tiagabine clearance is 60% greater in patients taking carbamazepine, phenytoin, phenobarbital, or primidone than in patients not on an enzyme inducer.(1)

Known hypersensitivity to tiagabine or any ingredient in the formulation.

There are no contraindication contraindications for this drug.

• Disease of liver
• Suicidal ideation

• Depression

Adverse effects occurring in 5% or more of patients receiving tiagabine in combination with other anticonvulsant drugs and more frequently than with placebo in clinical trials include dizziness/lightheadedness, asthenia/lack of energy, somnolence, nausea, vomiting, diarrhea, nervousness/irritability, tremor, abdominal pain, generalized pain, insomnia, ataxia, confusion, rash, pharyngitis, and difficulty with concentration or attention.

More Frequent

• Concentration difficulty
• Ecchymosis

Less Frequent

• Acute cognitive impairment
• Ataxia
• Depression
• Dysarthria
• Dyspnea
• Paresthesia
• Pneumonia
• Pruritus of skin

Rare or Very Rare

• Gait abnormality
• Gastrointestinal hemorrhage
• Hemorrhage
• Hostility
• Maculopapular rash
• Memory impairment
• Mood changes
• Neuropsychiatric disorder
• Nystagmus
• Skin rash
• Stevens-johnson syndrome
• Suicidal ideation
• Thrombocytopenic disorder
• Urinary tract infection

More Frequent

• Acute abdominal pain
• Chills
• Dizziness
• Drowsy
• Fever
• Flu-like symptoms
• General weakness
• Headache disorder
• Irritability
• Nausea
• Nervousness
• Pharyngitis
• Tremor
• Vomiting

Less Frequent

• Abnormal vaginal bleeding
• Acute bacterial otitis media
• Agitation
• Alopecia
• Aphthous stomatitis
• Arthralgia
• Back pain
• Bronchitis
• Chest pain
• Cough
• Depersonalization
• Diarrhea
• Dry skin
• Dysmenorrhea
• Dysuria
• Earache
• Edema
• Epistaxis
• Euphoria
• Fatigue
• Gingivitis
• Hallucinations
• Hyperhidrosis
• Hyperkinesis
• Hypertension
• Hypokinesia
• Hyporeflexia
• Hypotonia
• Increased appetite
• Insomnia
• Lymphadenopathy
• Malaise
• Migraine
• Muscle fasciculation
• Muscle weakness
• Myalgia
• Myoclonus
• Neck pain
• Pain
• Palpitations
• Paranoid disorder
• Peripheral edema
• Stupor
• Syncope
• Tachycardia
• Tinnitus
• Toxic amblyopia
• Urinary incontinence
• Vaginitis
• Vasodilation of blood vessels
• Vertigo
• Visual changes
• Weight gain
• Weight loss

Rare or Very Rare

• Accidental fall
• Behavioral disorders
• Blurred vision
• Bullous dermatitis
• Petechiae
• Rectal bleeding

No enhanced messaging available.

Safety and efficacy of tiagabine in children younger than 12 years of age have not been established.

Pharmacokinetic analysis indicates that clearance and volume of distribution of tiagabine are similar in pediatric patients (3-10 years of age) and adults receiving concomitant enzyme-inducing anticonvulsant drugs; however, in the non-induced population (e.g., those receiving non-inducing anticonvulsants such as valproate), clearance is increased in pediatric patients compared with adults.

There are no adequate and well-controlled studies of tiagabine in pregnant women; adverse effects on embryofetal development, including teratogenic effects, have been observed in animals. Tiagabine should be used during pregnancy only if clearly indicated.

Women who are pregnant while receiving tiagabine should be encouraged to enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry at 888-233-2334 (for patients); registry information also is available on the website http://www.aedpregnancyregistry.org.

Tiagabine and/or its metabolites are distributed into milk in rats; it is not known whether the drug is distributed into human milk. The effects of tiagabine on the nursing infant also are unknown. Tiagabine should be used in nursing women only if the benefits clearly outweigh the risks.

Clinical trials have not included sufficient numbers of patients older than 65 years of age to determine whether they respond differently than younger patients; safety and efficacy of tiagabine in geriatric patients have not been established. However, the pharmacokinetic profile of tiagabine in healthy geriatric adults was similar to that in younger adults.