Deconstructing tolerance with clobazam: Post hoc analyses from an open-label extension study.
OBJECTIVE
To evaluate potential development of tolerance to adjunctive clobazam in patients with Lennox-Gastaut syndrome.


METHODS
Eligible patients enrolled in open-label extension study OV-1004, which continued until clobazam was commercially available in the United States or for a maximum of 2 years outside the United States. Enrolled patients started at 0.5 mg·kg-1·d-1clobazam, not to exceed 40 mg/d. After 48 hours, dosages could be adjusted up to 2.0 mg·kg-1·d-1(maximum 80 mg/d) on the basis of efficacy and tolerability. Post hoc analyses evaluated mean dosages and drop-seizure rates for the first 2 years of the open-label extension based on responder categories and baseline seizure quartiles in OV-1012. Individual patient listings were reviewed for dosage increases ≥40% and increasing seizure rates.


RESULTS
Data from 200 patients were included. For patients free of drop seizures, there was no notable change in dosage over 24 months. For responder groups still exhibiting drop seizures, dosages were increased. Weekly drop-seizure rates for 100% and ≥75% responders demonstrated a consistent response over time. Few patients had a dosage increase ≥40% associated with an increase in seizure rates.


CONCLUSIONS
Two-year findings suggest that the majority of patients do not develop tolerance to the antiseizure actions of clobazam. Observed dosage increases may reflect best efforts to achieve seizure freedom. It is possible that the clinical development of tolerance to clobazam has been overstated.


BACKGROUND
NCT00518713 and NCT01160770.


METHODS
This study provides Class III evidence that the majority of patients do not develop tolerance to clobazam over 2 years of treatment.
From the School of Pharmacy and Department of Neurology (B.E.G.), University of Wisconsin, Madison; Idaho Comprehensive Epilepsy Center (R.T.W.), Boise; David Geffen School of Medicine at UCLA (R.S.), University of California-Los Angeles; School of Medicine (G.D.M.), Boston University, MA; School of Pharmacy (H.S.W.), University of Washington, Seattle; Center for Orphan Drug Research (J.C.C.), College of Pharmacy, University of Minnesota, Minneapolis; Prescott Medical Communications Group (M.C.K.), Chicago, IL; and Lundbeck LLC (G.P., D.M.T., V.S., J.I.), Deerfield, IL. barry.gidal@wisc.edu.
Barry E
BE
Gidal
From the School of Pharmacy and Department of Neurology (B.E.G.), University of Wisconsin, Madison; Idaho Comprehensive Epilepsy Center (R.T.W.), Boise; David Geffen School of Medicine at UCLA (R.S.), University of California-Los Angeles; School of Medicine (G.D.M.), Boston University, MA; School of Pharmacy (H.S.W.), University of Washington, Seattle; Center for Orphan Drug Research (J.C.C.), College of Pharmacy, University of Minnesota, Minneapolis; Prescott Medical Communications Group (M.C.K.), Chicago, IL; and Lundbeck LLC (G.P., D.M.T., V.S., J.I.), Deerfield, IL.
Robert T
RT
Wechsler
From the School of Pharmacy and Department of Neurology (B.E.G.), University of Wisconsin, Madison; Idaho Comprehensive Epilepsy Center (R.T.W.), Boise; David Geffen School of Medicine at UCLA (R.S.), University of California-Los Angeles; School of Medicine (G.D.M.), Boston University, MA; School of Pharmacy (H.S.W.), University of Washington, Seattle; Center for Orphan Drug Research (J.C.C.), College of Pharmacy, University of Minnesota, Minneapolis; Prescott Medical Communications Group (M.C.K.), Chicago, IL; and Lundbeck LLC (G.P., D.M.T., V.S., J.I.), Deerfield, IL.
Raman
R
Sankar
From the School of Pharmacy and Department of Neurology (B.E.G.), University of Wisconsin, Madison; Idaho Comprehensive Epilepsy Center (R.T.W.), Boise; David Geffen School of Medicine at UCLA (R.S.), University of California-Los Angeles; School of Medicine (G.D.M.), Boston University, MA; School of Pharmacy (H.S.W.), University of Washington, Seattle; Center for Orphan Drug Research (J.C.C.), College of Pharmacy, University of Minnesota, Minneapolis; Prescott Medical Communications Group (M.C.K.), Chicago, IL; and Lundbeck LLC (G.P., D.M.T., V.S., J.I.), Deerfield, IL.
Georgia D
GD
Montouris
From the School of Pharmacy and Department of Neurology (B.E.G.), University of Wisconsin, Madison; Idaho Comprehensive Epilepsy Center (R.T.W.), Boise; David Geffen School of Medicine at UCLA (R.S.), University of California-Los Angeles; School of Medicine (G.D.M.), Boston University, MA; School of Pharmacy (H.S.W.), University of Washington, Seattle; Center for Orphan Drug Research (J.C.C.), College of Pharmacy, University of Minnesota, Minneapolis; Prescott Medical Communications Group (M.C.K.), Chicago, IL; and Lundbeck LLC (G.P., D.M.T., V.S., J.I.), Deerfield, IL.
H Steve
HS
White
From the School of Pharmacy and Department of Neurology (B.E.G.), University of Wisconsin, Madison; Idaho Comprehensive Epilepsy Center (R.T.W.), Boise; David Geffen School of Medicine at UCLA (R.S.), University of California-Los Angeles; School of Medicine (G.D.M.), Boston University, MA; School of Pharmacy (H.S.W.), University of Washington, Seattle; Center for Orphan Drug Research (J.C.C.), College of Pharmacy, University of Minnesota, Minneapolis; Prescott Medical Communications Group (M.C.K.), Chicago, IL; and Lundbeck LLC (G.P., D.M.T., V.S., J.I.), Deerfield, IL.
James C
JC
Cloyd
From the School of Pharmacy and Department of Neurology (B.E.G.), University of Wisconsin, Madison; Idaho Comprehensive Epilepsy Center (R.T.W.), Boise; David Geffen School of Medicine at UCLA (R.S.), University of California-Los Angeles; School of Medicine (G.D.M.), Boston University, MA; School of Pharmacy (H.S.W.), University of Washington, Seattle; Center for Orphan Drug Research (J.C.C.), College of Pharmacy, University of Minnesota, Minneapolis; Prescott Medical Communications Group (M.C.K.), Chicago, IL; and Lundbeck LLC (G.P., D.M.T., V.S., J.I.), Deerfield, IL.
Mary Clare
MC
Kane
From the School of Pharmacy and Department of Neurology (B.E.G.), University of Wisconsin, Madison; Idaho Comprehensive Epilepsy Center (R.T.W.), Boise; David Geffen School of Medicine at UCLA (R.S.), University of California-Los Angeles; School of Medicine (G.D.M.), Boston University, MA; School of Pharmacy (H.S.W.), University of Washington, Seattle; Center for Orphan Drug Research (J.C.C.), College of Pharmacy, University of Minnesota, Minneapolis; Prescott Medical Communications Group (M.C.K.), Chicago, IL; and Lundbeck LLC (G.P., D.M.T., V.S., J.I.), Deerfield, IL.
Guangbin
G
Peng
From the School of Pharmacy and Department of Neurology (B.E.G.), University of Wisconsin, Madison; Idaho Comprehensive Epilepsy Center (R.T.W.), Boise; David Geffen School of Medicine at UCLA (R.S.), University of California-Los Angeles; School of Medicine (G.D.M.), Boston University, MA; School of Pharmacy (H.S.W.), University of Washington, Seattle; Center for Orphan Drug Research (J.C.C.), College of Pharmacy, University of Minnesota, Minneapolis; Prescott Medical Communications Group (M.C.K.), Chicago, IL; and Lundbeck LLC (G.P., D.M.T., V.S., J.I.), Deerfield, IL.
David M
DM
Tworek
From the School of Pharmacy and Department of Neurology (B.E.G.), University of Wisconsin, Madison; Idaho Comprehensive Epilepsy Center (R.T.W.), Boise; David Geffen School of Medicine at UCLA (R.S.), University of California-Los Angeles; School of Medicine (G.D.M.), Boston University, MA; School of Pharmacy (H.S.W.), University of Washington, Seattle; Center for Orphan Drug Research (J.C.C.), College of Pharmacy, University of Minnesota, Minneapolis; Prescott Medical Communications Group (M.C.K.), Chicago, IL; and Lundbeck LLC (G.P., D.M.T., V.S., J.I.), Deerfield, IL.
Vivienne
V
Shen
From the School of Pharmacy and Department of Neurology (B.E.G.), University of Wisconsin, Madison; Idaho Comprehensive Epilepsy Center (R.T.W.), Boise; David Geffen School of Medicine at UCLA (R.S.), University of California-Los Angeles; School of Medicine (G.D.M.), Boston University, MA; School of Pharmacy (H.S.W.), University of Washington, Seattle; Center for Orphan Drug Research (J.C.C.), College of Pharmacy, University of Minnesota, Minneapolis; Prescott Medical Communications Group (M.C.K.), Chicago, IL; and Lundbeck LLC (G.P., D.M.T., V.S., J.I.), Deerfield, IL.
Jouko
J
Isojarvi
D000293:Adolescent; D000328:Adult; D000927:Anticonvulsants / Q000627:therapeutic use*; D001569:Benzodiazepines / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D000078306:Clobazam; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D004361:Drug Tolerance; D005260:Female; D006801:Humans; D007206:Individuality; D065768:Lennox Gastaut Syndrome / Q000188:drug therapy*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome; D014481:United States; D055815:Young Adult
D000927:Anticonvulsants; D001569:Benzodiazepines; D000078306:Clobazam
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