Effect of other drugs on riluzole metabolism- In vitro studies using human liver microsomal preparations suggests that CYP1A2 is the principal isoenzyme involved in the initial oxidative metabolism of riluzole and therefore potential interaction may occur when riluzole is given concurrently with agents that affect CYP 1A2 activity.

The potenrial inhibitors (eg. caffeine, theophylline, amitriptylene, quinolones) could decrease the rate of riluzole elimination. whereas, inducers of CYP 1A2 (eg. cigerettes, smoke, charcoal- boiled food, rifampin, omeprazole)could increase the rate of riluzole elimination.

Amyotrophic lateral scelerosis

Approved by FDA on December 12, 1995

Asthenia, nausea, diziness, diarrhea, anorexia, vertigo, somnolence, circumoral parasthesia, decreased lung function, abdominal pain, pneumonia, vomiting.

Severe hypersenstiviity reactions to riluzole or any the tablet components

Special precautions:

Monitoring serum aminotransferases including SGPT levels before and during therapy.

Approved by FDA on December 12, 1995

Amyotrophic lateral scelerosis

Dosage:

Recemmended dose is 50mg evry 12 hrs. NO increased benefit can be expected from higher daily doses, bur adverse events are increased.

Take at least 1 hr before or 2 hours after a meal to avoid decreased bioavailability.

1. Advise patients to report any febrile illness to their physicians.

2. Advise patients to take riluzole at the same time of the day)eg morning and evening ) each day. If the dose is missed, take the next tablet as originally planned.

3. Warn patients of the potential for dizziness, vertigo, or somnolence and advise them not to drive or operate machinery until they have gained sufficient experience on riluzole to gauge whether or not it affects the mental or motor peformance adversely.

4. Discourage riluzole treated patients from drinking alcohol.

Pharmacology:

The etiology and pathogenesis of amyptrophic sclerosis(ALS ; Lou Gehrig's disease ) are not known. Its pharmacological activity is unknown, but could be related to its effect

1. an inihibitory effect on glutamate release;

2. inactivation of voltage dependent sodium channels and

3. ability to interfere with intracellular events that follow transmiter binding

Pharmacokinetics:

Riluzole is well absorbed with average absolute bioavailability of about 50%. Pharmacokinetics are linear over a a dose range of 25 to 100mg every 12 hrs. A high fat meal decreases absorption, reducing AUC about 20% and peak blood levels by about 485%. The mean elimination half-life of riiluzole is 12 hrs after repeated doses.

Pregnancy:

Use during pregnancy only if the potential benefits outweigh the potential risks.

Lactation:

Advise women not to breast feed during treatment with riluzole.