Br J clin Pharmac 1995; 39: 449-451
`Absorption of clonazepam afterintranasal and buccal
`administration
`
`M. W. G. SCHOLS-HENDRIKS', J. J. H. M. LOHMAN', R. JANKNEGT1, J. J. KORTEN2, F. W. H. M. MERKUS3
`& P. M. HOOYMANS1
`'Department of Clinical Pharmacy and Toxicology, 2Department of Neurology, Maasland Hospital, Sittard and
`3the Center for Bio-Pharmaceutical Sciences, University of Leiden, Leiden, The Netherlands
`
`Serum concentrations of clonazepam after intranasal, buccal and intravenous admini-
`stration were compared in a cross-over study in seven healthy male volunteers. Each
`subject received a 1.0 mg dose of clonazepam intranasally and buccally and 0.5 mg
`intravenously. A Cmax of 6.3 ± 1.0 ng ml-' (mean; ± s.d.) was measured 17.5 min
`(median) (range 15-20 min) after intranasal administration. A second peak (4.6 ± 1.3
`ng ml-') caused by oral absorption was seen after 1.7 h (range 0.7-3.0 h). After
`buccal administration a Cmax of 6.0 ± 3.0 ng ml-' was measured after 50 min (range
`30-90 min) with a second peak of 6.5 ± 2.5 ng ml-' after 3.0 h (range 2.0-4.0 h).
`Two minutes after i.v. injection of 0.5 mg clonazepam the serum concentration was
`27 ± 18 ng ml-'. It is concluded that intranasal clonazepam is an alternative to buccal
`administration. However, the Cmax of clonazepam after intranasal administration is
`not high enough to recommend the intranasal route as an alternative to intravenous
`injection.
`Keywords
`
`clonazepam
`
`absorption
`
`intranasal
`
`buccal
`
`pharmacokinetics
`
`Introduction
`For adequate treatment of status epilepticus or serial
`clonazepam,
`rapid
`the
`seizures
`with
`attainment
`of effective concentrations is necessary and, con-
`sequently, intravenous injection is generally the route
`of choice.
`In several institutions in The Netherlands buccal
`administration of clonazepam is used in mentally
`retarded children with serial seizures [1]. However,
`accurate buccal clonazepam dosing is
`difficult in
`patients
`hypersalivation.
`convulsions
`with
`and
`In these situations intranasal administration may be
`an alternative. Intranasal administration is also more
`convenient
`administration. We have
`than
`rectal
`a clonazepam solution
`developed
`for
`intranasal
`administration. The nasal formulation for clonazepam
`dimethyl-,-cyclodextrin (DM3CD) as
`contains
`a
`solubilizer and absorption enhancer. Cyclodextrins
`are biocompatible polymers, able to form inclusion
`complexes with drugs. Clonazepam is virtually water
`insoluble. However, stable aqueous solutions can be
`prepared with DMiCD [2]. The aim of this study was
`to compare serum concentrations of clonazepam after
`intranasal, buccal and intravenous administration.
`
`Methods
`Subjects and protocol
`The study involved seven healthy male volunteers
`aged 26 to 58 years, weighing from 69 to 82 kg. All
`were healthy and took no other medication. The
`protocol was approved by the local Ethics Committee
`and all volunteers gave written informed consent.
`Intranasal clonazepam (5 mg ml-) was prepared
`by dissolving clonazepam (Bufa, The Netherlands)
`together with dimethyl-,3-cyclodextrin (Avebe, The
`Netherlands) in a molar ratio of 1:8 in 96% v/v
`ethanol. The solvent was evaporated and the residue
`redissolved in 0.9% w/v saline. The pH was adjusted
`to 3.0. The intranasal spray device was a unit-dose
`pump (Pfeiffer GmbH, Germany).
`The subjects participated in three test sessions at
`2 week intervals. During the sessions they received a
`1.0 mg dose of intranasal or buccal clonazepam or
`0.5 mg clonazepam intravenously. Each intranasal
`dose was administered in one spray of 0.1 ml in both
`nostrils. Clonazepam was administered buccally b
`rubbing 0.4 ml of a 2.5 mg ml-' solution (Rivotril
`solution, Roche, The Netherlands) into
`the
`oral
`
`Correspondence: Dr M. W. G. Schols-Hendriks, Department of Clinical Pharmacy, Maasland Hospital, P.O. Box 5500, 6130 MB
`Sittard, The Netherlands
`449
`
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`

`

`M. W G. Schols-Hendriks et al.
`450
`buccal mucous membrane. After administration the
`volunteer was instructed not to swallow the solution
`for as long as possible and not to speak for 1
`h.
`Clonazepam (Rivotril® injection, Roche, The Nether-
`lands) was injected into a forearm vein at a dose of
`0.5 mg over 2 min. The medication was given after
`an overnight fast. Two hours after administration a
`normal diet was resumed.
`Venous blood samples were taken at 0, 2, 5, 10, 15,
`20, 30, 40, 60, 90 min, 2, 3, 4, 6, 8 and 24 h after
`dosing. The serum samples were stored at -20° C
`until analysis.
`
`Drug analysis
`To 0.5 ml serum were added 100 gl water, 50 pl
`desmethyldiazepam in ethanol 96% (2.5 gg ml-',
`internal standard) and 200 pl borax buffer solution
`0.04 mol 1-l (pH 9.0), and the mixture was extracted
`with dichloromethane. The organic phase was sepa-
`rated and evaporated to dryness. The residue was
`dissolved in mobile phase and injected onto the
`column.
`The h.p.l.c. system consisted of a Waters-Millipore
`486 tunable absorbance detector, a 510 injector, a
`U6K pump and a Spectra Physics Data jet integrator
`for determination of peak heights. The column (30
`cm x 3.9 mm i.d.) was packed with ,u-Bondapak C18
`(Waters-Millipore, The Netherlands). The mobile
`phase (pH 3.6) consisted of a mixture of acetonitrile,
`methanol and phosphate buffer solution 6 mmol 1-l
`(180 + 200 + 500). The flow rate was 2.0 ml min-'.
`U.v. detection was at 210 nm. Calibration curves
`were linear (r > 0.999) up to 50 ng ml-'. The limit of
`determination was 2 ng ml-' at which concentration
`the intra-run coefficient of variation was 16%. The
`inter-run coefficient of variation was 10% for a 4 ng
`ml-' solution.
`
`Data analysis
`Values of AUC(0,2 h) were calculated using a com-
`bination of the linear- and log-trapezoidal methods.
`The highest observed concentration and the corre-
`
`sponding sampling time were defined as Cmax and
`tmax, respectively.
`Differences
`in pharmacokinetic
`variables were
`examined using the Student's t-test for paired data.
`Data are reported as mean ± s.d. To assess the stati-
`stical
`significance of the difference between the
`administration routes the 95% CI for the mean differ-
`ence was calculated.
`
`Results
`Mean serum concentrations of clonazepam after intra-
`venous, intranasal and buccal administration
`are
`shown in Figure 1. After intravenous administration
`the concentrations declined over the first 10-15 min
`such that after 20 to 40 min they were similar to the
`peak values after buccal and intranasal administra-
`tion. After 2 h no significant differences in serum
`drug concentrations were observed between the
`different routes of administration. All participants
`completed the study. Intravenous data for one subject
`were excluded from analysis because of extravasation
`during the injection. Serum drug concentrations after
`buccal administration to another subject could not be
`measured because of chromatographic interference.
`Values of Cmax and tmax are shown in Table 1.
`
`.E
`wO.O
`Time lmn)
`CO)
`Figure 1 Mean (+ s.d.) serum clonazepam concentrations
`after intravenous (0.5 mg, A), buccal (1.0 mg, V) and
`intranasal (1.0 mg, *) administration of clonazepam.
`
`90
`
`.1:20
`
`Cmax and tmax values following the administration of 0.5 mg clonazepam intravenously and 1.0 mg bucally and
`Table 1
`intranasally to seven healthy male volunteers
`Intranasal
`tmaxJ
`Cmax 2
`(ng ml')
`(min)
`5.5
`4.5
`3.0
`3.5
`5.0
`7.0
`4.0
`4.6
`1.3
`
`Cmax I
`(ng mbl')
`6.0
`4.5
`7.0
`6.5
`7.5
`6.5
`6.3
`1.0
`
`Subject
`1
`20
`2
`20
`3
`20
`4
`5
`15
`6
`15
`7
`15
`Mean
`17.5
`± s.d.
`Range
`15-20
`*No data because of extravasation.
`tNo data because of analytical interference.
`
`tmax,2
`(h)
`2.0
`2.0
`1.0
`3.0
`1.5
`0.7
`2.0
`1.7
`0.7-3.0
`
`Cmax I
`(ng ml-)
`4
`3
`9
`9
`7
`3
`t
`6.0
`3.0
`
`Buccal
`tmax,
`Cmax 2
`(ng mh-,)
`(min)
`9
`40
`6
`30
`40
`40
`4
`60
`90
`t
`50
`30-90
`
`t
`6.5
`2.5
`
`Intravenous
`t
`C
`(ng ml-')
`(min)
`5
`2
`*
`*
`50
`2
`15
`2
`20
`2
`45
`2
`25
`2
`27
`2.0
`18
`
`tmax,2
`(h)
`3.0
`2.0
`4.0
`
`t
`3.0
`2.0-4.0
`
`AQUESTIVE EXHIBIT 1131 Page 0002
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`

`

`reached
`peak
`drug
`concentrations
`Initial
`were
`significantly faster after intranasal compared with
`buccal administration (P < 0.05; 95% CI for the mean
`difference: 1.3 to 66.7 min). The differences in these
`maximum concentrations after intranasal (6.3 ± 1.0
`ng ml-) and buccal (6.0 ± 3.0 ng ml-') admini-
`stration did not reach statistical significance (P > 0.5;
`95% CI for the mean difference : -4.4 to +4.6
`ng ml-').
`After intravenous administration of 0.5 mg drug
`the mean AUC(0,2 h) was 11 ± 3 ng ml-' h.
`Relative, dose-normalised AUC(0,2 h) values after
`buccal and intranasal administration were 0.41 and
`0.45, respectively.
`
`Discussion
`After both intranasal and buccal administration of
`clonazepam two peak serum drug concentrations were
`
`References
`1 Overweg J, Binnie CD. Benzodiazepines in neurlogical
`In The benzodiazepines: From molecular
`disorders.
`biology to clinical practice, ed Costa E. New York:
`Raven Press, 1983: 339-347.
`2 Hermens WA, Deurloo MJ, Romeijn SG, Verhoef J,
`Merkus FW. Nasal absorption enhancement of 17,B-
`estradiol by dimethyl-p-cyclodextrin in rabbits and rats.
`Pharm Res 1990; 7: 500-503.
`3 Pinder RM, Brogden RN, Speight TM, Avery GS.
`
`Short report
`451
`obtained in six of seven and three of six subjects,
`respectively. The first peak was presumed to reflect
`initial rapid mucosal absorption and the second was a
`consequence of oral absorption.
`The usual intravenous administered dose of clon-
`azepam is at least 1.0 mg. However, a dose of 0.5 mg
`was used in this study for safety reasons. In studies in
`patients with status epilepticus therapeutic benefit
`was associated with serum clonazepam concentra-
`tions ranging from 13 to 90 ng ml-' [3]. A thera-
`peutic concentration threshold of 18 ng ml-' has been
`suggested [4]. However, after buccal and intranasal
`administration of 1.0 mg clonazepam, concentrations
`above 18 ng ml-' were not observed in this study.
`Therefore we conclude that, although intranasal
`clonazepam (1.0 mg) is an alternative to buccal
`administration in patients with serial seizures, initial
`serum drug concentrations are too low to recommend
`its use as an alternative to intravenous injection in
`patients with status epilepticus.
`
`Clonazepam: A review of its pharmacological properties
`and therapeutic efficacy in epilepsy. Drugs 1976; 12:
`321-361.
`4 Rylance GW, Poulton J, Cherry RC, Cullen RE. Plasma
`concentrations of clonazepam after single rectal admini-
`stration. Arch Disease Childh 1986; 61: 186-188.
`(Received 2 August 1994,
`accepted 24 November 1994)
`
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