comparison of potential cytoprotective action of sucralfate and cimetidine: studies with...

Comparison of Potential Cytoprotective Action of Sucralfate and Cimetidine

Studies with Experimental Feline Esophagitis

SCO-IT CLARK, B.S. PHILIP 0. KATZ, M.D. WALLACE C. WU, M.D. KIM R. GEISINGER, M.D.* DONALD 0. CASTELL, M.D.

Winston-Salem, Notth Carolina

From the Gastroenterology Section, Department of Medicine and Department of Pathology, Bowman Gray School of Medicine, Wake Forest University Medical Center, Winston-Salem, North Carolina. Requests for reprints should be addressed to Dr. Philip 0. Katz, Division of Digestive Diseases, Francis Scott Key Medical Center, 4940 Eastern Avenue, Baltimore, Maryland 21224.

*American Cancer Society Junior Faculty Clinical Scholar.

The potential mucosai protective effects of a liquid sucraifate prepa- ration and the histamine (H&antagonist cimetidine on acid-induced esophagitis were studied. Esophagitis was induced in adult cats using a constant infusion of 0.1 N hydrochloric acid at 1 ml/minute for 20 minutes. Mucosai lesions were evaluated by blinded investi- gators using both fiber-optic endoscopy and light microscopy. His- tology was scored for basal ceil hyperpiasia, intraepitheiiai ieukocy tosis, and subepitheiiai ieukocytosis. Liquid sucraifate given prior to acid infusion consistently prevented acid-induced lesions, dem- onstrated by quantitative histologic scoring. Although cimetidine did not show the same degree of protection as sucraifate, the re- suits did show a trend towards a cytoprotective effect.

Current treatment of gastroesophageal reflux disease is primarily aimed at acid neutralization, augmentation of lower esophageal sphincter pressure, and improving esophageal clearance [l]. Although breakdown in epithelial defenses is believed to play a role in the pathogenesis of gastroesophageal reflux disease, there is, at present, no available therapeu- tic agent that affords local esophageal mucosal protection from stomach refluxate.

Sucralfate, the basic aluminum hydroxide salt of sucrose-octasulfate, and cimetidine, a histamine (H&receptor antagonist, have been shown to be effective in the prevention and treatment of peptic ulcer disease. Both have been shown, experimentally, to have a cytoprotective effect on gastric mucosa. if either of these agents were to have cytoprotective effects on esophageal mucosa, it might add considerably to the medical therapy of gastroesophageal reflux disease. Sucralfate cytoprotection has been shown against acid-induced esophageal lesions in one study in cats [2] and against pepsin-induced esophageal lesions in the rabbit [3]. Esophageal mucosal resistance of rabbit esophagus appears to be en- hanced by sucralfate as well [4]. One study has presented evidence that cimetidine may have a direct cytoprotective effect on the rabbit esophagus [5]. The current study compares the effect of liquid sucralfate and cimetidine on acid-induced esophageal mucosal injury in cats.

MATERIALS AND METHODS

Adult cats weighing 3 to 5 kg were anesthetized with 15 mg/kg of intramuscu- lar ketamine hydrochloride on the day of study. All animals were studied in the left lateral decubitus position after an overnight fast and were allowed to swal- low ad lib during the study. On Day 0, animals underwent baseline fiber-optic

59 September 29, 1987 The American Journal of Medicine Volume 93 (suppl 38)

SYMPOSIUM ON SUCRALFATE-CLARK ET AL

1 upper endoscopy (Olympus GIF-XPlO pediatric endoscope). Esophageal acid injury was induced by a constant infusion of 0.1 N hydrochloric acid administered through a pediatric feeding tube placed 5 cm above the endoscopic gastroesophageal junction. Acid was infused at a rate of 1 ml/miQute for 20 minutes. This is a modification of a previously de- scribed technique of acid-induced esophagitis in cats [6].

Four groups of cats were studied; (1) 12 cats pretreated with 200 mg (10 ml) of topical cimetidine or identically ap- pearing liquid placebo using a 20-minute acid infusion; (2) 12 cats pretreated with 200 mg (10 ml) of topical cimetidine or liquid placebo using a 30-minute acid infusion: (3) eight cats pretreated with intraperitoneal cimetidine (100 mg/kg) or intraperitoneal saline using a 20-minute acid infusion; and (4) six cats pretreated with 1 g (10 ml) of topical sucralfate using a 20-minute acid infusion. The topical treatments were infused through the feeding tube 10 minutes prior to acid infusion, and the intraperitoneal treatments were given 30 minutes prior to acid infusion. Throughout the study, the investi- gators were blinded to the sequence of drug or placebo.

On the day following acid infusion (24 hours later), animals were killed by carbon dioxide inhalation or intravenous pento- barbital, and the esophagus was removed in toto and imme- diately placed in 10 percent formalin. The entire distal 5 cm was processed routinely for histology, stained with hematoxy- lin and eosin, and evaluated by a pathologist blinded to the drug sequence. The specimen was scored for basal cell layer hyperplasia, intraepithelial leukocytes, and subepithelial leukocytes. Basal cell layer hyperplasia was defined as the ratio of basal cell layer thickness to total mucosal thickness. Meas- urements of the basal cell layer and total mucosal thickness were performed using an ocular micrometer, and basal cell layer hyperplasia was scored as: 0, less than 15 percent; 1 +, 15 to 40 percent; 2+, more than 40 percent. lntraepithelial leukocytes were scored as number per high-powered field: 0, none; 1+, 1 to 2/high-power field; 2+, more than 2/high- power field. Subepithelial leukocytes were similarly scored: 0, none; 1 +, 1 to 4/high-power field; 2+, at least S/high-power field. In addition, the linear extent of injury for each of basal cell layer hyperplasia, intraepithelial leukocytes, and subepithelial leukocytes was scored as follows: 0, single microscopic focus; 1, 2 to 4 microscopic foci; 2, more than 4 microscopic foci. The scores for basal cell layer hyperplasia, intraepithelial leukocytes, and subepithelial leukocytes were added, so each cat received a total esophagitis score of 0 to 12. This scoring system was developed as the result of con-

TABLE I Total Esophagitis Score

12

10

0 : +Ll - IpCim IPS

y - Clm

(30 min) (30 min)

- - min) (20 mln) (20 min) (20 min)

F 7gure 1. Mean values for total esophagitis score , for groups of cats receiving topical cimetidine (Cim) versus placebo (PI) prior to 20- or 30-minute acid infusions. Also shown are mean scores for groups of cats receiving intraperitoneal cimetidine (IpCim) and Maperitoneal saline (/pS). Vertical lines indicate r 1 SE.

sideration of histologic changes seen in human reflux esophagitis and histologic changes seen in preliminary studies in the cat. The following comparisons were made. Comparison I: Protection with Topical Cimetidine on Dif- ferent Degrees of Acid Esophagitis. Six cats were pretreated with topical cimetidine and 20-minute acid infusion, and six cats were pretreated with cimetidine and 30-minute acid infusion; each group was compared with a placebo group of six cats receiving pretreatment with placebo. Comparison II: Protection with Different Modes of Cimet- idlne Treatment. Six cats were pretreated with topical cimetidine, and four were pretreated with intraperitoneal cimetidine prior to a 20-minute acid infusion: each group was compared against an appropriate placebo group (topical placebo or intraperitoneal saline). Comparison Ill: Protection with Sucralfate versus Cimeti- dine. Six cats were pretreated with topical sucralfate, six with topical cimetidine, and six with topical placebo, all receiving a 20-minute acid infusion. Statistics. Data were analyzed using the Student t test for unpaired samples and the Mann-Whitney test where appropriate.

Cat Cim

(20 minutes) (20 mYlutes) IpClm

(20 minutes) Saline

(20 minutes) Clm

(30 minutes) (30 mtutes)

1 0 12 12 12 12 2 12 12 3 12 12 3 7 12 12 11 12 4 8 12 12 12 12 5 IO 12 12 8 12 8 12

Mean 8.2 11.3 9.8 11.8 12 SE 1.8 0.7 2.3 0.3 0

11 12 12 11 12 12 11.7

0.2

Cim = topical cimetidine, 100 mg (10 ml); PI = topical placebo (10 ml); IpCim = intraperitoneal’cimetidine (100 mg/kg).

September 28, 1987 The American Journal of Medicine Volume 83 (suppl 38) 57


1 lrn min) (

t

min) 1 IpCim

(2U min)

- Cim

mm) ’ (30 min) (30 min)

-

gure 2. Mean percent basal cell hyperplasia for groups c cats receiving topical cimetidine (Urn) or placebo (Pl) prior to 20- or 30-minute acid infusion. Also mean percent hyperplasia for groups of cats receiving intraperitoneal cimetidine (IpCim) or intraperitoneal saline (IpS). Vertical lines indicate k 1 SE.

RESULTS

Comparison I. The degree of esophagitis created by acid infusion showed a trend towards better protection by topical cimetidine compared with placebo with the shorter total acid infusion (20 minutes). The mean total esophagitis score was 8.2 + 1.8 (*SE) with cimetidine and 11.3 r 0.7 with placebo (p = 0.08). This effect was not found with the 30-minute acid infusion (12.0 + 0.0 versus 11.7 k 0.2) (Figure 1, Table I). No trend was noted for basal cell hyperplasia (Figure 2, Table II). Comparison II. lntraperitoneal cimetidine produced no significant difference in total esophagitis score or degree of basal cell hyperplasia compared with placebo after a 20-minute acid infusion. (total esophagitis score: 9.8 2 2.3 versus 11.8 f 0.3; percent of basal cell layer hyperplasia: 55.0 + 5.0 versus 52.5 ? 8.3 percent). Also, the mode of cimetidine dosage (intraperitoneal versus topical

TABLE II Percent Basal Cell Hyperplasia

cimetidine) resulted in no difference in total esophagitis score or basal cell layer hyperplasia (total esophagitis score: 9.8 rt 2.3 versus 8.2 t 1.8; basal cell layer hyperplasia: 46.7 ? 9.0 versus 55.0 +- 5.0 percent). These results are shown in Figures 1 and 2 and in Tables I and II. Comparison Ill. The degree of basal cell hyperplasia and total esophagitis scores were significantly lower (p ~0.01) in cats pretreated with topical sucralfate compared with placebo (percent of basal cell layer hyperplasia: 15.8 f 4.5 versus 45.5 + 6.3 percent; total esophagitis score: 1.2 k 1.2 versus 11.3 2 0.7) (Figure 3). The degree of basal cell layer hyperplasia showed no difference in cats pretreated with topical cimetidine (46.7 2 9.0 percent) compared with placebo (Figure 4). Although no significant difference could be shown between the total esophagitis score for topical cimetidine compared with placebo, as noted earlier, a trend (p = 0.08) was present (8.2 ? 1.8 versus 11.3 + 0.7). The major difference was noted in the degree of tissue leukocytes, particularly subepithelial (Tables Ill and IV).

COMMENTS

It is now well accepted that sucralfate has cytoprotective effects against gastric mucosal injury to many caustic agents in several animal models [7]. Ample evidence for gastric cytoprotection in humans is also suggested by studies showing the drug’s ability to prevent stress ulcera- tion in critically ill patients [8] and mucosal damage from aspirin [9] and other nonsteroidal anti-inflammatory drugs [lo]. In addition, sucralfate has been shown to prevent duodenal ulcer recurrence [ll], suggesting that the com- pound protects duodenal mucosa as well.

The cytoprotective property of sucralfate appears to apply also to esophageal injury. The current study con- firms previous observations from our laboratory that liquid sucralfate prevents esophageal mucosal injury caused by acid in the cat esophagus [2]. Sucralfate has also been shown to prevent esophageal injury in rabbits exposed to a single, one-hour pepsin infusion [3] and to prevent the increase in short-circuit current seen with exposure of rabbit esophageal mucosa to acid [4].

Cat Cim

(20 minutes) (20 mktes) IpCim

(20 minutes) Saline

(20 minutes) Cim

(30 minutes) (30 mkes)

1 8 8 50 50 75 75 2 70 45 65 70 80 70 3 45 45 50 40 75 80 4 42 45 100 50 80 45 5 85 50 65 65 6 50 20 60 60

Mean 46.7 45.5 55.0 52.5 69.2 65.8 SE 9.0 8.3 5.0 6.3 3.5 5.1

Cim = topical cimetidine, 100 mg (10 ml); PI = topical placebo (10 ml); IpCim = intraperitoneal cimetidine (100 mg/kg).

58 September 28, 1987 The American Journal of Medicine Volume 83 (suppl 38)


I

F Figure 3. Comparison of mean total esophagitis scores for groups of cats receiving topical sucralfate (Sue), placebo (PI}, or cimetidine (Cim) prior to a 20-minute acid infusion. Vertical lines indicate 2 1 SE.

- Cim

p<o.oi p=o.oa

TABLE III Intraepithelial Leukocytes (degree/extent)

60

20

10

0 Cim

rl p-co.01 NS Figure 4. Mean percent basal cell hyperplasia for groups of cats receiving topical sucralfate (SW), placebo (PI), or cimetidine (Cimj prior to 20-minute acid exposure. Vertical lines indicate 2 1 SE.

t

Cat Cim

(20 minutes) (20 m!Lttes) IpCim

(20 minutes) Saline

(20 minutes) Cim

(30 minutes) (30 mktes)

1 o/o 2 212 3 l/l 4 2/l 5 210 6 212

Mean 1.511 .o SE 0.310.4

212 212 212 212 212 210

2.011.7 010.3

2l2 2l2 2/2 010 212 212 212 212 212 2l2 2/2 212

212 242

1.511.5 212 212 0.510.5 010 010

2/l 212 212 212 212 212 211.6 010.2


TABLE IV Subepithelial Leukocytes (degree/extent)

Cat Cim

(20 minutes) (20 m!Ltes) IpCim

(20 minutes) Saline

(20 minutes) Cim

(30 minutes) (30 m\utes)

1 2 3 4 5 6

Mean SE

o/o 212 110 110 212 212

1.311 .o 0.310.4

212 212 212 212 212 212 2l2 010

212 212 212 o/o 212 212 212 212 212 212 2/2 212

212 212

1.5l1.5 212 212 0.5lO.5 010 010

212 212 212 212 212 212 2/2 o/o


September 28, 1987 The American Journal of Medicine Volume 83 (suppl 38) 59


Because cimetidine has the ability to suppress gastric acid secretion, it is difficult to evaluate a true cytoprotective effect of this drug, particularly on gastric mucosa. We used the model of infusing exogenous acid to create esophagitis to negate any possible effects of cimetidine on acid production. Therefore, only the potential direct action of cimetidine protecting the esophageal mucosa was evaluated. Acid was used instead of other noxious agents in order to simulate gastroesophageal reflux disease, the most common cause of esophagitis in humans. In addition, since the most distal 5 cm is the area most likely affected by gastroesophageal reflux disease, the model used simulated the most common setting for esophagitis.

Our study showed that topical cimetidine produces a trend towards direct protection of the esophageal mucosa at lesser degrees of acid-induced injury. The differentiat- ing factor of this direct esophageal protection seems to be

primarily related to the prevention of subepithelial leukocytosis rather than basal cell hyperplasia or intraepithelial leukocytosis. Although gastric acid inhibition is the pri- mary mode of action of cimetidine, some recent studies have suggested direct protection of the gastric mucosa against aspirin injury in rats [12] and protection of the rat esophageal mucosa against bile salt injury [5].

It appears, then, that of the currently available agents effective in the treatment and prevention of acid peptic disease, sucralfate shows the best evidence of cytoprotection against esophageal mucosal injury. Our study suggests that cimetidine may offer some direct protection, but not to the same degree as sucralfate. Whether sucralfate or cimetidine will be most effective in combina- tion with other therapies, as a single agent, or as “reflux prophylaxis” awaits further evaluation. Studies in humans are needed to confirm the observations in this, and in other animal models.

REFERENCES

1. Richter JE, Castell DO: Gastroesophageal reflux. Pathogene- 7. Okabe S, Takeuchi K, Kunimi H, et al: Effect of an antiulcer sis, diagnosis, and therapy. Ann Intern Med 1982; 97: 93- drug, sucralfate, on experimental gastric lesions and gastric 103. secretion in rats. Dig Dis Sci 1983; 28: 1304-1342.

2. Katz PO, Geisinger KR, Hassan M, et al: Acid-induced esopha- 8. Borrero E, Margolis I, Bank S, Shulman N, Chardavoyne R: Ant- gitis in cats is prevented by sucralfate but not synthetic pros- acid versus sucralfate in preventing acute gastrointestinal taglandin E. Dig Dis Sci (in press). bleeding. A randomized trial in critically il l patients. Am J Surg

3. Schweitzer EJ, Barr BL, Johnson LF, Harmon JW: Sucralfate 1984; 148: 809-812. prevents experimental peptic esophagitis in rabbits. Gastro- 9. Tester MA, Lim ES: Protection of gastric mucosa by sucralfate enterology 1985; 88: 61 l-61 9. from aspirin-induced erosions. J Clin Gastroenterology 1983;

4. Orlando RC, Powell DW: Effect of sucralfate on esophageal epi- 3 (suppl 2): 171-175. thelial resistance to acid in the rabbit (abstr). Gastroenterol- 10. Caldwell JR: Sucralfate in the relief of gastrointestinal symp- ogy 1984; 86: 1201. toms associated with non-steroidal anti-inflammatory drugs.

5. Salo JA, Kivilaakso E: Effect of cimetidine on HCI-taurocholate- South Med J 1985; 78: 938-940. induced esophageal mucosal injury. Acta Chir Stand 1984; 11. Marks IN, Lathe W, Wright JP, et al: Ulcer healing and relapse 150: 647-652. rates after initial treatment with cimetidine or sucralfate. J Clin

6. Eastwood GL, Caste11 DO, Higgs RH: Experimental esophagitis Gastroenterol 1981; 3 (suppl 2): 163-165. in cats impairs lower esophageal sphincter pressure. Gastro- 12. Guth PH, Aures D, Paulsen G: Topical aspirin plus HCI gastric enterology 1975; 69: 146-153. lesions in the rat. Gastroenterology 1979; 76: 88-93.

80 September 28, 1987 The American Journal of Medicine Volume 83 (suppl 3B)

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