Oral Mucosal Adhesive Film Containing Local Anesthetics:
`In Vitro and Clinical Evaluation
`
`Keiko Yamamura, 1 Saori Ohta, 1 Kohji Yano, 1 Toshihisa Yotsuyanagi, 2 Tomomitsu Okamura, 3
`Toshitaka Nabeshima 1
`
`1 Department of Neuropsychopharmacology and Hospital Pharmacy, Nagoya University School of Medicine, Tsuruma-cho,
`Showa-ku, Nagoya 466, Japan
`
`2 Faculty of Pharmaceutical Sciences, Nagoya City University, Nagoya 467, Japan
`
`3 Department of Obstetrics and Gynecology, Nagoya University School of Medicine, Tsuruma-cho, Showa-ku,
`Nagoya 466, Japan
`
`Received 3 March 1997; accepted 19 August 1997
`
`In vitro and in vivo studies were conducted to gauge the effectiveness of a
`Abstract:
`novel oral mucosa adhesive, moderately water-soluble, pliant polymer artificial dentifrice
`(AD) film containing dibucaine (DC) for relief of pain due to oral erosion. The film was
`prepared from a hydroxypropyl cellulose-M (HPC-M) ethanol solution containing varying
`amounts of DC, as well as polyethylene glycol. In the in vitro experiments, the disintegra-
`tion of HPC-M showed a lag time of about 50 min, a much lower rate than that of drug
`release, which more or less leveled off after 50 min. Twenty-five percent of the DC was
`released from the film (0.113 and 0.225 mg/cm2) after the initial 5 min, which then
`reached about 80% after 50 min, the time at which the polymer began to break up. In
`the in vivo study, the local anesthetic effect of the film was evaluated in 23 patients (10
`males, 13 females) suffering from the adverse effects of chemotherapy. When applied to
`the wet surface of the mucosa, the AD film absorbed moisture and showed excellent
`adhesion. Pain relief in patients lasted 2.2 { 0.21 and 4.3 { 0.25 h at DC doses of 0.113
`and 0.225 mg/cm2, respectively. These results suggest that the AD film may cover mucosi-
`tis sites of oral mucosa long enough to allow DC release and bring relief from pain arising
`from chemotherapy and/or radiotherapy. q 1998 John Wiley & Sons, Inc. J Biomed Mater Res
`(Appl Biomater) 43: 313–317, 1998
`
`Keywords: mucosa adhesive film; hydroxypropyl cellulose; mucositis; local anesthetics;
`pain relief
`
`INTRODUCTION
`
`Radiotherapy and chemotherapy are the usual modes of
`treatment for various types of cancer. A typical adverse
`effect of this cytotoxic treatment is serious aphthae and
`subsequent erosion on the oral mucosa and tongue. The
`accompanying pain is almost intolerable and can last for up
`to 2 weeks. Oral mucosal erosion and mucositis frequently
`complicate treatment and adversely affect patient comfort,
`nutrition, speech, and treatment compliance.
`The development of an external drug delivery system
`
`Correspondence to: Dr. K. Yamamura
`No benefit of any kind will be received either directly or indirectly by the
`authors.
`
`q 1998 John Wiley & Sons, Inc.
`
`CCC 0021-9304/98/030313-05
`
`is currently the subject of considerable interest. Mucosal
`adhesive systems are envisaged as safe and effective thera-
`peutic means for drug administration in the treatment of
`aphthae and erosion on the oral mucosa 1,2 and have even
`been explored for the purpose of bypassing the liver in
`first-pass metabolism.3,4 These systems basically consist of
`adhesive films or matrices comprising water-soluble poly-
`mer in which drugs are incorporated.
`The extemporaneous preparation of a water-soluble
`polymer film containing local anesthetics and antibiotics
`was requested by physicians in our hospital. The film had to
`be mucosa adhesive, moderately water-soluble, and pliant
`because it was intended to be applied to highly irritable
`areas of the oral mucosa and/or tongue. In a preliminary
`study, we reported the use of a mucosa-soluble adhesive
`film containing tetracaine in the treatment of two leukemia
`patients with severe aphthae and subsequent erosion in-
`duced by radiation and chemotherapy on the oral mucosa
`
`313
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`314
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`YAMAMURA ET AL.
`
`temperature for 1 h until the film was completely dissolved
`in the water. The concentration of DC dissolved in the
`media was assayed by high-performance liquid chromatog-
`raphy (HPLC; LC-9A system, Shimadzu Corp., Kyoto)
`under the following conditions: Deverosil ODSN-5 re-
`versed-phase column (Shimadzu Corp.); phosphoric acid
`(0.001%)-acetonitrile (60:40) eluent; 1.2 mL/min flow
`rate; detection, UV at 240 nm. The recoveries of DC from
`the films ranged from 95 to 105%; the coefficients of varia-
`tion were (cid:155)5%.
`Although several apparatuses have been used to evaluate
`in vitro drug release behavior, 6,7 for the most part the only
`consideration has been the release rate of the drug incorpo-
`rated while disintegration of the polymeric matrix due to
`contact with water has been ignored. No suitable device
`has been found so far for the measurement of drug release
`from a water-soluble matrix, making it difficult to perform
`a quantitative study of drug release. Therefore, we designed
`a diffusion cell to measure not only the release rate of an
`incorporated drug but also the disintegration rate of the
`matrix (Fig. 1). The diffusion cell, fabricated entirely of
`acrylic resin, had three components: a top cover, a ring-
`type sheet-fixing device, and a double-jacketed chamber
`for temperature control. The cell was vertically divided
`into two compartments by a collagen sheet. The sheet was
`pushed down and fixed by the ring device, which was
`carefully machined to fit in the part of the cell and treated
`so that only the central dotted portion remained permeable.
`The magnetic stirring bar (30 1 8 mm) was driven by
`a constant-rate adjustable stirrer (Aimex AS-2T, Tokyo
`Seisakusho Co., Tokyo) positioned directly beneath the
`apparatus. The sampling port, which was an ordinary rub-
`
`Figure 1. Diffusion cell for testing drug release from a water-soluble
`film and polymer disintegration.
`
`Scheme 1. Preparation of the AD film.
`
`and tongue.5 Pain relief continued for 4 to 6 h in the patients
`receiving the film, allowing them to sleep.
`The objective of this study was to evaluate the effect
`of local anesthetic on pain in patients with severe oral
`erosion induced by chemotherapy after application of arti-
`ficial dentifrice (AD) film containing dibucaine (DC) to
`oral mucosa.
`In the in vitro experiment, the release rate of DC from
`the AD film and the disintegration rate of the polymer
`were compared, because the effectiveness of this form of
`treatment can be compromised if the latter is not substan-
`tially less than the former.
`
`MATERIALS AND METHODS
`
`In Vitro Study
`
`Hydroxypropyl cellulose-M (HPC-M; JP grade, Nippon
`Soda Co., Tokyo), polyethylene glycol 400 (PEG 400;
`Wako Pure Chemical Co., Osaka), and DC (Sigma Chemi-
`cal Co., St. Louis) were used. A nonwoven collagen sheet
`(MEIPAC, 0.1-mm thickness; Meiji Confectionery Co.,
`Tokyo), which was used as support for the film, was
`washed overnight in distilled water. HPC-M (600 mg) was
`dissolved in ethanol (20 mL) to which DC (5 or 10 mg)
`and PEG 400 (10 mg) were added and mixed (Scheme
`1). The resulting ethanol solution was placed in a level
`Teflon dish (7.5-cm diameter) and dried overnight under
`slightly negative pressure in a desiccator. The DC film
`formed was translucent, 0.12 { 0.05 mm thick, and pliant
`even after drying. No precipitate of the drug was detected
`under polarization microscopy.
`Film for the final application was cut into 2-cm squares
`that were determined to contain 0.113 or 0.225 mg/cm2
`DC each in the 5- and 10-mg samples, respectively, by the
`following method: several 2-cm squares were soaked in 10
`mL of distilled water in a capped vial and shaken at room
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`MUCOSA-ADHESIVE FILM CONTAINING LOCAL ANESTHETICS
`
`315
`
`ber stopper from an injection vial, was installed on the side
`of the lower chamber. The rubber stopper made possible
`repeated sampling of 10 to 20 mL for HPLC assay over
`time.
`The diffusion cell (capacity 47.9 mL) was first filled
`with buffer solution (pH 7.0) until it reached slightly above
`the top level of the chamber on which the collagen sheet
`was placed so that it was wetted by solution and pushed
`down by the ring-type device, leaving no air bubbles in
`the chamber. Excess solution on the sheet was decanted
`and blotted; at the same time, it was assured that the surface
`of the wet sheet remained smooth. The film was cut to a
`diameter of 28 mm and was placed directly onto the colla-
`gen sheet. Water maintained at 37 7C circulated through
`the jacketed cell from a water bath at a constant controlled
`rate. An aliquot (10–20 mL) was withdrawn with a micro-
`syringe through the rubber sampling port at appropriate
`intervals. The same volume of the solution withdrawn was
`returned to the chamber at each sampling. The released
`drug and disintegrated HPC-M were assayed by HPLC.
`The amount of disintegrated HPC-M was determined by
`a Shimadzu RID-6A differential refractive index detector
`under the following conditions: column, Shodex OHpak
`KB-804 (Shimadzu Corp.); NaNO3 (0.1 M) solution eluent;
`0.5 mL/min flow rate.
`The clinical application of AD films containing local
`
`anesthetics requires that the latter remain stable for long
`periods. Because high temperature is a critical factor in
`promoting drug degradation, we decided to measure the
`temperature conditions necessary for the preservation of
`films. DC films were prepared by the procedure described
`above and followed for 84 days under different storage
`conditions at 40 7, 50 7, and 60 7C.
`
`Clinical Study
`
`A two-part clinical study was conducted. All subjects
`granted informed consent per a protocol approved by the
`Nagoya University Ethics Committee on Human Research.
`In the first part of the study, 10 healthy volunteers (five
`males and five females) were selected to evaluate the anal-
`gesic effects of the AD film after oral mucosal application.
`A single 0.9-mg DC film was applied to the right buccal
`mucosa and a drug-free film to the left buccal mucosa.
`Using a questionnaire, subjects evaluated the effectiveness
`of the films in terms of time until onset of numbness and
`numbness duration time.
`The second part of the study utilized 23 patients (10
`males, 13 females) with malignant tumors who were re-
`ceiving chemotherapy treatment. AD film was applied to
`patients with mucositis presenting as erythema or a blister
`membrane; in all patients the diameter of the mucositis
`
`Figure 2. Release rates of dibucaine and HPC-M polymers from the AD films across a collagen sheet
`(mean { SD, n (cid:129) 5); bulk phase, pH 7.0 phosphate buffer (47.9 mL, 37 7C); agitation, 50 rpm.
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`316
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`YAMAMURA ET AL.
`
`TABLE I. Percentage of Dibucaine Remaining in AD Films after
`84-Days Storage at Various Temperatures
`
`TABLE III. Analgesic Affects of AD Films in Patients
`with Oral Mucositis
`
`Remaining (%)
`
`Patient
`
`Pain Free
`
`Original Drug Concn
`(mg/cm2/film)
`
`50 7C
`40 7C
`97.2 { 0.1
`97.5 { 0.3
`0.113
`98.2 { 0.3
`98.9 { 0.2
`0.225
`Values represent mean { SD; n (cid:129) 5 for each sample group.
`
`60 7C
`96.5 { 0.2
`97.2 { 0.2
`
`Drug Concn
`(mg/cm3)
`
`0.113
`
`was (cid:155)20 mm and there was only mild contact pain. Patients
`were divided into two groups: 11 patients (five males, six
`females) receiving the 0.113-mg DC film and 12 patients
`(five males, seven females) receiving the 0.225-mg DC
`film. Evaluation was expressed in terms of pain-free onset
`time and pain-free duration time.
`
`RESULTS
`
`In Vitro Study
`
`Figure 2 shows cumulative percentages of DC released
`from films and amount of disintegrated HPC-M. DC (0.113
`and 0.225 mg/cm2) was rapidly released from films incu-
`bated in buffer solution without appreciable lag time.
`Twenty-five percent of DC was released from the film by
`5 min; the proportion reached approximately 80% after 50
`min, at which time the polymer had still not disintegrated.
`Disintegration of HPC-M showed a lag time of about 50
`min and proceeded much longer than drug release, which
`reached a more or less constant rate of release after 50 min.
`Table I shows the results of stability tests for DC in the
`AD films at three different temperatures (407, 507, and 60
`7C). The DC in the films was stable for up to 84 days at
`any temperatures examined.
`
`Clinical Study
`
`When the film was applied to the wet surface of the oral
`mucosa in all subjects, it swelled and demonstrated excel-
`lent adhesion.
`Table II shows the clinical evaluation of AD films by
`healthy volunteers. Mean numbness onset time was 3.3 {
`
`TABLE II. Anesthetic Effects of AD Films Applied
`to Oral Mucosa in Healthy Volunteers
`
`Numbness
`
`Onset Time
`(min)
`3.3 { 1.1
`No affect
`
`Duration
`(h)
`1.6 { 0.14
`No affect
`
`Drug Concn
`
`n
`
`10
`0.225
`10
`0
`Values are mean { SD.
`
`Sex
`
`Age
`(years)
`
`F
`F
`F
`F
`F
`F
`M
`M
`M
`M
`M
`
`F
`F
`F
`F
`F
`F
`F
`M
`M
`M
`M
`M
`
`38
`35
`30
`29
`42
`46
`29
`66
`48
`58
`47
`
`48
`42
`34
`28
`41
`55
`51
`52
`56
`61
`62
`57
`
`Duration
`(h)
`
`Onset Time
`(min)
`(cid:155)5
`(cid:155)5
`(cid:155)5
`(cid:155)5
`(cid:155)5
`(cid:155)5
`(cid:155)5
`(cid:155)5
`(cid:155)5
`(cid:155)5
`(cid:155)5
`2.2 { 0.21a
`(cid:155)5
`(cid:155)5
`(cid:155)5
`(cid:155)5
`(cid:155)5
`(cid:155)5
`(cid:155)5
`(cid:155)5
`(cid:155)5
`(cid:155)5
`(cid:155)5
`(cid:155)5
`4.3 { 0.25a
`
`2.5
`2.0
`3.0
`1.5
`1.5
`3.0
`2.5
`2.0
`3.0
`2.0
`1.0
`
`4.0
`5.0
`5.5
`4.0
`3.0
`4.0
`3.5
`4.5
`5.0
`4.0
`3.0
`5.5
`
`0.225
`
`a Mean { SD.
`
`1.1 min, and numbness duration was 1.6 / 0.14 h for doses
`of 0.225 mg/cm2 applied to the right buccal mucosa. No
`analgesic effect was noted for the drug-free film applied
`to the left buccal mucosa.
`Table III shows the clinical evaluation of AD films in
`patients with oral mucositis. Pain-free onset time was (cid:155)5
`min in all patients, irrespective of DC dose. Pain-free dura-
`tion time was 2.2 { 0.21 and 4.3 { 0.25 h for DC doses
`of 0.113 and 0.225 mg/cm2, respectively. Three of the 23
`patients reported strange sensations in the mouth at the
`time of application of the film. No serious or unexpected
`adverse experiences were observed during or after applica-
`tion in any patient.
`The data obtained in the 84 days of accelerated stability
`studies at temperatures up to 60 7C suggest that our DC–
`HPC-M film formulations should have a shelf life of at
`least 2 years.8
`
`DISCUSSION
`
`It is important for patients with oral erosion that the pain-
`free onset time be as short as possible and thus that the
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`MUCOSA-ADHESIVE FILM CONTAINING LOCAL ANESTHETICS
`
`317
`
`release rate of the drug from the film be as high as possible.
`The release rate of a drug incorporated into a water-soluble
`polymeric matrix is closely related to the penetration rate
`of the water into that matrix. The interpretation of this
`release behavior is complex due to a variety of factors
`associated with the disintegration of the matrix; these gen-
`erally include the penetration of water into the matrix,
`swelling of the polymer structure, and the start of disinte-
`gration after a maximal point of swelling is reached. To
`simplify such a complex system, it may be beneficial to
`keep the matrix as thin as possible.9 The films examined
`in this study were about 0.1 mm thick, which also made
`them sufficiently pliant for easy application to oral lesions.
`The AD film seemed to swell rapidly because its surface
`appeared to become thoroughly wetted within 30 to 50 s
`of placing it on the collagen sheet. As a consequence, the
`drug incorporated into the film seemed to dissolve and
`released into the buffer solution in vitro and into saliva in
`vivo at a rapid rate.
`The results of the first part of our clinical study showed
`that AD films, but not drug-free films, had analgesic effects.
`Pain relief in all patients began in (cid:155)5 min. The results of
`the clinical evaluation are in good agreement with the rapid
`release behavior of DC in the in vitro study in which about
`25% of the DC was released in the initial 5 min without
`appreciable lag time. Pain-free duration time in patients
`appeared to depend on the quantity of drug in the films.
`Furthermore, the disintegration rate of the film was much
`slower than drug release, which may thus be expected to
`protect the oral mucosa while relieving pain.
`These results suggest that an AD film containing DC
`may be a useful means for providing relief of the pain
`associated with oral mucositis induced by chemotherapy
`
`and/or radiotherapy. The advantages of this material are
`that it provides rapid pain-free onset time and the polymer
`matrix covers the affected area over a sustained period.
`Further studies are needed to confirm the efficacy of this
`approach in effecting lasting pain-free duration for various
`degrees of oral mucositis.
`
`REFERENCES
`
`1. Yamasaki, K.; Shibata, Y.; Imai, S.; Tani, Y.; Shibasaki, Y.;
`Fukuhara, T. Clinical application of prostaglandin E1
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`2. Leveque, F. G.; Parzuchowski, J. B.; Farinacci, G. C., et al.
`Clinical evaluation of MGI 209, an anesthetic, film forming
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`7. Aguiar, A. J.; Weiner, M. A. Percutaneous absorption studies
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`8. Martin, A.; Swarbrick, J.; Cammarata, A., Eds. Physical
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`Pharmacy, 3rd edition. Philadelphia, PA: Lea & Febiger;
`1983:412–418.
`
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`580B
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`Par Pharm., Inc., et al.
`Exhibit 1013
`Page 005
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