Determination of 5-ASA in Whole or Partial Mesalamine Delayed-Release Tablets Recovered
`From Fecal Samples of Healthy Volunteers:
`Do 5-ASA Delivery Systems Matter in the Treatment of Ulcerative Colitis?
`
`Poster Number
`
`Alan Safdi, MD • Michael Safdi, MD
`Greater Cincinnati Gastroenterology Associates, Cincinnati, OH
`
`ABSTRACT
`Purpose: Mesalamine delayed-release tablets (ASACOL®; Procter and Gamble
`Pharmaceuticals) have a coating of methacrylic acid polymer B (EUDRAGIT S) that
`allows release of mesalamine to the proximal colon with low systemic absorption
`(approximately 28%). This coating is pH-sensitive and dissolves at a sustained pH level
`of 7 or higher. Fragments of ASACOL tablets have been observed in fecal specimens,
`but the fragments were believed to be shells left after the 5-aminosalycilic acid
`(5-ASA) had been released. The current study was conducted to determine the amount
`of 5-ASA in whole and partial mesalamine tablets recovered from the fecal samples of
`healthy volunteers who received mesalamine therapy.
`
`Methods: Thirty healthy volunteers received two 400-mg mesalamine tablets
`orally twice a day for 4 days. After observing the presence of whole and partial
`mesalamine tablets in fecal specimens, the investigators recovered the tablets and
`fragments for further analysis. The tablets and fragments recovered from fecal
`specimens were photographed, crushed, and added to 20 mL 0.1 M sodium
`phosphate (pH 6.0) and 80 mL absolute methanol. After resting at room temperature
`for 4 hours, 40 mL of the solution was placed in a centrifuge for 10 minutes.
`Three 10-mL aliquots of supernatant were removed, frozen, and sent to a laboratory to
`be assayed for 5-ASA with a lower limit of quantification of 2000 ng/mL.
`
`Results: Of 30 volunteers, 27 (90%) provided fecal samples. Of these, 15 volunteers
`(55%) presented with at least 1 mesalamine tablet or fragment in at least 1 fecal
`sample.
`
`No. of Volunteers (%)
`
`No. Specimens Containing Mesalamine
`Tablets or Fragments (Total)
`
`11 (40)
`
`3 (11)
`
`1 (4)
`
`1 (11)
`
`2 (6)
`
`4 (4)
`
`Total Volunteers 15 (55)
`
`Total Specimens 21
`
`All tablets and fragments recovered had detectable 5-ASA. Mean recovery was 97.2 ±
`47.1 mg per tablet/fragment-approximately 24% of an intact tablet.
`
`Conclusions: Fifty-five percent of healthy volunteers who received oral mesalamine
`delayed-release tablets over 4 days of treatment excreted whole or partial tablets in at
`least 1 fecal specimen. Because all tablets and fragments recovered had
`detectable 5-ASA, it is clear that the recovered tablets and fragments were not just
`physical matrices, inert shells, or other excipients. Mean recovery was 97.2 ± 47.1 mg
`per tablet/fragment-approximately 24% of an intact mesalamine tablet. Only visually
`detectable fragments were measured in this study; additional undetectable fragments
`could have been present. The actual percentage of unreleased mesalamine may be
`higher than reported here, representing an important fraction of the daily
`mesalamine dose.
`
`Background
`Mesalamine acts topically in the colon to reduce inflammation associated with
`inflammatory bowel disease. To achieve maximum effectiveness in the treatment of
`ulcerative colitis (UC), mesalamine must reach the colon intact. pH-dependent delayed-
`release mesalamine (Asacol®; Procter and Gamble Pharmaceuticals) tablets have a
`methacrylic acid polymer B coating (Eudragit S) designed to dissolve at a sustained pH
`level of 7 or higher, which is generally found in the distal ileum and colon. However, pH
`levels vary widely throughout the colon, and in as many as 25% of healthy individuals, pH
`levels do not reach 7 in any section of the gastrointestinal tract (Figure 1).
`
`9
`
`4 11
`
`3
`2
`1
`0
`
`Median
`10th Percentile
`25th Percentile
`75th Percentile
`-s- 90th Percentile
`
`Sto Duo Pro Mid Dis Cec1Asc Ira Des RIS Fec
`
`Colonic Delivery
`
`Figure 1. pH profile of the gastrointestinal tract in healthy volunteers as measured by a radiotelemetry device,
`shown as percentage of all pH values by intraluminal location of the capsule. Sto=stomach; Duo=duodenum;
`Pro=proximal small intestine; Mid=mid small intestine; Dis=distal small intestine; Cec=cecum; Asc=ascending
`colon; Tra=transverse colon; Des=descending colon; R/S=sigmoid colon or rectum; Fec=feces. From
`Fallingborg et al. Aliment Pharmacol Ther. 1989;3:605-613. With permission from Blackwell Publishing.
`
`In patients with active UC, pH levels may be even lower, dropping to as low as 2.3 in
`the cecum and transverse colon. These variances in pH levels may result in incomplete
`dissolution of pH-dependent tablets, reducing the amount of active drug available in the
`colon. Patients who respond poorly to pH-dependent delayed-release mesalamine may
`have an improved response rate with an agent that delivers a higher percentage of 5-ASA
`directly to the colon (Figure 2).
`
`Figure 2. Drug delivery throughout the gastrointestinal tract.
`
`Objective
`To determine the amount of 5-ASA in whole and partial mesalamine tablets recovered
`from the fecal samples of healthy volunteers who received mesalamine therapy.
`
`Methods
`• Patients: 30 healthy volunteers
`
`• Treatment: Each patient received two 400-mg pH-dependent delayed-release
`mesalamine tablets by mouth
`
`• Duration: 4 days
`
`• Analysis of excreted tablets and fragments:
`
`- Although not part of the original protocol, we observed the presence of tablets and
`fragments in stool samples and chose to further examine this interesting finding.
`
`- After the presence of whole or partial tablets was observed in fecal specimens, the tablets
`and fragments were recovered for further analysis.
`
`- Stool specimens were collected during the 4-day treatment period as part of routine blood,
`urine, and fecal sample collection.
`
`- All stool samples were collected and analyzed separately.
`
`- Tablets and fragments were photographed, removed from the feces, and refrigerated in
`sealed plastic bags (Figures 3a and 3b).
`
`Figures 3a and 3b. Examples of pH-dependent delayed-release mesalamine tablets and fragments recovered
`from stool samples collected from healthy volunteers. Volunteers received two 400-mg delayed-release
`mesalamine tablets by mouth for 4 days.
`
`- Tablets were crushed and added to 20 mL 0.1 M sodium phosphate (pH 6.0) plus 80 mL
`absolute methanol, mixed thoroughly, and allowed to stand at ambient temperature for
`4 hours.
`
`- The solution was mixed thoroughly, and 40 mL was placed in a centrifuge for 10 minutes.
`
`- Three 10-mL aliquots of supernatant were removed, added to capped test tubes, frozen at
`-70°C, and shipped frozen to a laboratory to be assayed for 5-ASA with a lower limit of
`quantification of 2000 ng/mL (13.06 pM).
`Results
`• Ninety percent of the volunteers (27) provided fecal samples.
`
`• Of these, 55% (15 volunteers) presented with at least 1 mesalamine tablet or fragment
`in at least 1 fecal sample.
`
`No. Specimens
`Containing Mesalamine
`Tablets or Fragments
`
`No. Volunteers (%)
`
`Total No. Specimens
`Containing
`Mesalamine Tablets
`or Fragments*
`
`1
`
`2
`
`4
`
`Total
`
`11 (40)
`
`3 (11)
`
`1 (4)
`
`15 (55)
`
`11
`
`6
`
`4
`
`21
`
`No. specimens x no. patients.
`
`• All whole and partial tablets had detectable levels of 5-ASA.
`
`• Mean 5-ASA recovered per tablet or fragment was 97.2 ± 47.1 mg, approximately 24%
`of the amount in an intact tablet.
`
`Discussion
`Our finding that 55% of healthy volunteers excreted whole or partial tablets with
`detectable levels of 5-ASA-approximately 24% of an intact mesalamine tablet-is
`noteworthy. Because we only measured visually detectable fragments in this study,
`additional undetectable fragments may have been present. The actual percentage of
`unreleased mesalamine may be higher than reported here, representing an important
`fraction of the daily mesalamine dose.
`
`The pH-dependent delivery mechanism of delayed-release mesalamine tablets may
`contribute to the incomplete release of mesalamine in the colon. The polymer coating
`begins dissolving at a sustained pH level of 7, which is found in the distal ileum and
`colon. However, pH levels in the gastrointestinal tract vary, and in some healthy
`individuals, pH levels do not reach 7 in any section of the gastrointestinal tract.
`
`Azo-bonded prodrugs are not dependent on pH levels. The compounds undergo
`azo-reduction in the colon to release the 5-ASA molecule. In the case of balsalazide,
`99% of the 5-ASA is delivered to the colon intact.
`
`The release of 5-ASA proximal to the colon from pH-dependent delayed-release
`mesalamine tablets results in systemic absorption, leading to serum levels of 5-ASA
`4.5 times higher than after administration of equimolar doses of balsalazide.
`(Figure 4). Premature absorption of 5-ASA reduces the amount of active drug that
`reaches the colon.
`
`Figure 4. Plasma 5-ASA and N-acetyl-5-ASA levels at 2 weeks in patients with ulcerative colitis who received
`balsalazide 2.25 or 6.75 g/day or pH-dependent delayed-release mesalamine 2.4 g/day. *p=0.01 vs Asacol.
`tp=0.018 vs Asacol. •*Colazal® is a registered trademark of Salix Pharmaceuticals, Inc. From Levine et al. Am J
`Gastroenterol. 2002;97:1398-1407. With permission from Blackwell Publishing.
`
`• In direct comparisons of balsalazide and pH-dependent delayed-release mesalamine
`for the treatment of UC, balsalazide was more effective earlier in the treatment process
`than pH-dependent delayed-release mesalamine in terms of clinical response and
`complete remission. It is believed that azo-bonded delivery systems such as
`balsalazide provide a more reliable mechanism to deliver 5-ASA directly to the colon.
`
`• Our finding of whole and partial tablets with detectable levels of 5-ASA suggests the
`pH-dependent drug delivery mechanism of delayed-release mesalamine results in
`incompletely dissolved tablets and inadequate delivery of 5-ASA to the colon. Azo-
`bonded delivery systems such as balsalazide may be effective salvage therapy for
`patients with UC who respond poorly to or are intolerant of pH-dependent delayed-
`release mesalamine.
`
`
`
`1111 Presented at the 70th Annual American College of Gastroenterology Meeting
`October 28-November 1, 2005; Honolulu, Hawaii
`
`References: Asacol [package insert]. Cincinnati, OH: Procter and Gamble Pharmaceuticals; March 2004. • Colazal [package insert]. Morrisville, NC: Salix Pharmaceuticals, Inc; April 2005. • Fallingborg J, Christensen LA, Ingeman-Nielsen M, Jacobsen BA, Abildgaard K, Rasmussen HH. pH-profile and regional transit times of the normal gut measured by a radiotelemetry device. Aliment Pharmacol Ther. 1989;3:605-613. • Fallingborg J, Christensen LA,
`Jacobsen BA, Rasmussen SN. Very low intraluminal colonic pH in patients with active ulcerative colitis. Dig Dis Sci. 1993;38:1989-1993. • Green JRB, Lobo AJ, Holdsworth CD, et al. Balsalazide is more effective and better tolerated than mesalamine in the treatment of acute ulcerative colitis. Gastroenterology 1998;114:15-22. • Hanauer SB. Medical therapy of ulcerative colitis. Lancet 1993;342:412-417. • Levine DS, Riff DS, Pruitt R, et al. A randomized,
`double blind, dose-response comparison of balsalazide (6.75 g), balsalazide (2.25 g), and mesalamine (2.4 g) in the treatment of active, mild-to-moderate ulcerative colitis. Am I Gastroenterol. 2002;97:1398-1407. • Nugent SG, Kumar D, Rampton DS, Evans OF. Intestinal lumina! pH in inflammatory bowel disease: possible determinants and implications for therapy with aminosalicylates and other drugs. Gut 2001;48:571-577. • Patel DG, Das KM. An open-
`label comparison of COLAZAL® (balsalazide disodium) and US Asacol® (mesalamine) in patients with ulcerative colitis. Poster presented at: Digestive Disease Week; May 17-22, 2003; Orlando, FL. • Pruitt R, Hanson J, Safdi M, et al. Balsalazide is superior to mesalamine in the time to improvement of signs and symptoms of acute mild-to-moderate ulcerative colitis. Am J Gastroenterol. 2002;97:3078-3086.
`
`SALIXN00012323
`
`Dr. Falk Ex. 2030
`GeneriCo v. Dr. Falk IPR2016-00297
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