Effect of verapamil and diltiazem on isolated gastro-oesophageal sphincter of the rat

Topical diltiazem ointment in post-hemorrhoidectomy pain relief: A meta-analysis of randomized controlled trials

BACKGROUND

Hemorrhoidectomy is commonly associated with postoperative pain. Calcium channel blockers are known to cause relaxation of gastrointestinal smooth muscle and oral diltiazem has also been shown to reduce the resting anal pressure.

OBJECTIVE

We attempted to analyze efficacy and side effects of topical diltiazem oint. in post-operative pain control.

METHODS

This is a meta-analysis of patients who underwent hemorrhoidectomy using topical diltiazem oint. versus placebo (Vaseline) for pain control. Patients with third or fourth degree hemorrhoids undergoing traditional hemorrhoidectomy were included. Procedures took place in the colorectal division of a hospital in 5 countries. Five randomized control trials (RCTs) published between 2005 and 2016 including 227 patients were included our meta-analysis (Diltiazem (calcium channel block) group = 137; Placebo (Vaseline) group = 90). Pain assessment was performed using a standardized Visual Analogue Scale. Any side effects of surgery or medication use, which were noted by the patient or the surgeon, also were recorded.

RESULTS

A total of 227 patients were included in the meta-analysis. The results revealed that Diltiazem ointment was statistically significant in reducing pain within 48 h, at 72 h, and more than 96 h after operation compared to the placebo group. Regarding overall complications (including headache), there was no statistical significance between diltiazem and placebo group.

CONCLUSIONS

Topical application of diltiazem effectively relieves pain after hemorrhoidectomy with minimal side effects. Further large studies are needed to substantiate its value in clinical practice.

Comparison of observational and controlled clinical trials of diltiazem in the treatment of chronic anal fissure

Diltiazem has been extensively studied in the treatment of chronic anal fissures, but efficacy in clinical practice is not fully established. The aim of the present study was to evaluate the safety and efficacy of topical application diltiazem in observational studies as well as in controlled clinical trials in the treatment of chronic anal fissures. A systematic literature search was carried out from 1966 to 31 December, 2007 on PubMed, Medline, Embase and Cochrane database, using the appropriate search words. We found six observational studies with 392 patients and five controlled clinical trials with 289 patients in which topical diltiazem treatment was given. Efficacy was found to be very high in observational studies (56.88%), whereas it was found to be modest in controlled clinical trials (29.41%). In observational studies, most of the patients reported complete healing of fissures within 6-12 weeks, whereas in controlled trials healing was reported within 8 weeks, with tolerable adverse effects of diltiazem. On the basis of the above studies, it can be concluded that topical application of diltiazem is useful in the treatment of chronic anal fissure, but to fully establish its efficacy, larger prospective double-blind study is required in the near future.

Effects of Calcium Antagonists on Rat Normal and Skinned Fundus

Calcium chloride (CaCl2) (0·1−25 Mm, in K+-depolarized tissue), KCl (10−112 Mm) and acetylcholine (1 × 10−9 m−1 Mm) produced concentration-dependent contractions of rat isolated fundus. Verapamil (0·01−100 μm), cinnarizine (1−100 μm), trifluoperazine (10−500 μm) and dantrolene (50−250 μm) each produced a concentration-related rightward and downward shift of the log concentration-effect curve for CaCl2. The rank order of potencies of these antagonists, measured as the IC50 against Ca2+ (25 Mm)-induced contraction of depolarized fundus, was verapamil (2.5 μm) > cinnarizine (8·7 μm) > trifluoperazine (85·1 μm) > dantrolene (> 250 μm). Cinnarizine (0·5 Mm) and trifluoperazine (0·5 Mm), but neither verapamil nor dantrolene depressed Ca2+ (20 μm)-evoked contraction of rat skinned fundus preparations. In intact preparations of rat fundus, verapamil had greater inhibitory effects on contractions produced by KCl than against those elicited by acetylcholine while trifluoperazine depressed to the same extent the responses to these two spasmogens. Dantrolene was without effect on contractions elicited by KCl or acetylcholine. Cinnarizine inhibited acetylcholine-induced responses but enhanced contractions to KCl. Augmentation of KCl-induced responses by cinnarizine is resistant to verapamil (1 μm). This enhancing effect of cinnarizine was not observed for KCl-induced contraction of guinea-pig fundus or rat gastro-oesophageal sphincter. In the rat fundus, cinnarizine (1−100 μm) produced an additional and concentration-related contraction when added on the plateau contraction to KCl (100 Mm). The enhancing effect and the direct contraction produced by cinnarizine are at least partly dependent on extracellular Ca2+. It is concluded that distinct differences exist between the calcium antagonists examined. The action of verapamil is restricted to the plasmalemma whereas cinnarizine and trifluoperazine also act on the intracellular contractile machinery. Dantrolene is scarcely effective as a calcium antagonist in rat fundus.

Calcium channel blockers and motility disorders of the esophagus

In animal experiments, esophageal smooth muscle, including the lower esophageal sphincter (LES) has been shown to be dependent on extracellular calcium both for tone and agonist induced contractions. Calcium channel blockers (CCB) suppress contractile activity, and block both resting and stimulated calcium influx. In normal man as well as in patients with hypercontractility disorders of the esophagus, such as achalasia and diffuse esophageal spasm, CCBs have been shown to reduce LES pressure and esophageal contractions, and also to cause symptomatic improvement. Controlled clinical trials on their effectiveness are lacking, but the therapeutic principle seems promising.

Topical diltiazem and bethanechol decrease anal sphincter pressure and heal anal fissures without side effects

PURPOSE

Topical glyceryl trinitrate heals anal fissures, but a majority of patients experience headache. Topical gels of the calcium channel blocker diltiazem and the cholinomimetic bethanechol significantly lower anal sphincter pressure in volunteers. This study investigated the use of these two new pharmacologic agents in the treatment of patients with chronic anal fissure.

METHODS

Two studies were conducted, each involving 15 patients with chronic anal fissure. In each study patients underwent anal manometry and laser doppler flowmetry before treatment. They were treated with either 2 percent diltiazem gel or 0.1 percent bethanechol gel three times daily for eight weeks. Assessment every two weeks was by clinical examination, repeat anal manometry, and laser doppler flowmetry. Daily pain was assessed by linear analog charts.

RESULTS

Fissures healed in 10 of 15 (67 percent) patients treated with 2 percent diltiazem gel and in 9 (60 percent) patients treated with 0.1 percent bethanechol gel. There was no significant difference in the pretreatment maximum resting sphincter pressure (MRP) between responders and nonresponders in either group. There was significant reduction in the pain score after treatment with diltiazem (P = 0.002) and bethanechol (P = 0.005) compared with that before treatment. MRP was significantly lower after diltiazem (P = 0.0001) and bethanechol (P = 0.02) compared with pretreatment MRP. No headaches or side effects were reported.

CONCLUSIONS

Both topical diltiazem and bethanechol substantially reduce anal sphincter pressure and achieve fissure healing to a similar degree reported with topical nitrates, but without side effects.

Tetrodotoxin-sensitive and -insensitive relaxations in the rat oesophageal tunica muscularis mucosae

1. Relaxation responses were produced by vagal and field stimulation, respectively, of the whole oesophagus preparation from the rat and of the isolated tunica muscularis mucosae (t.m.m.) preparation from the rat. These relaxation responses persisted in the presence of antagonists of histamine, serotonin, noradrenaline and acetylcholine. 2. Unlike vagally evoked relaxation, that evoked by low-frequency field stimulation, i.e. field-stimulated relaxation (f.s.r.) was generally resistant to tetrodotoxin (TTX). 3. Both types of relaxations exhibited remarkable temperature sensitivity and were abolished by lowering the bath temperature from 37 to 28 degrees C. 4. TTX-resistant relaxations were also produced by scorpion (Leiurus quinquestriatus) venom, the calcium ionophore, A23187 (calimycin) and by increasing the extracellular potassium by 2 mM. The failure of these agents to inhibit f.s.r. is inconsistent with a releasing and/or depleting action on any endogenous mediator. 5. Relaxations produced by vasoactive intestinal peptide (VIP) could be blocked by alpha-chymotrypsin which, however, failed to abolish f.s.r., suggesting that VIP is not the mediator of f.s.r. 6. F.s.r. was completely blocked by the calcium channel antagonists, verapamil (10(-6) M), nifedipine (10(-7) M), and by magnesium (20 mM). 7. Our results indicate that TTX-insensitive relaxations in the isolated t.m.m. are dependent upon extracellular calcium, are due to activation of potential-operated calcium channels and are not mediated by VIP.

Effects of calcium channel blockers on gastric emptying and acid secretion of the rat in vivo

Experiments were designed to evaluate the effects of three calcium channel blockers (verapamil, diltiazem and cinnarizine) on gastric emptying and secretion in the rat. Pretreatment with the calcium blockers delayed gastric emptying of phenol red in a dose-dependent manner. Verapamil was the most effective of the agents tested. Verapamil and diltiazem inhibited gastric acid secretion in the pylorus-ligated rat without affecting pepsin output. Cinnarizine was ineffective in this model. When the perfused lumen of the anaesthetized rat was used, verapamil was found to inhibit responses to carbachol or histamine more than those to pentagastrin. Further, we found a greater sensitivity to verapamil for basal compared with vagal-stimulated (2-deoxy-D-glucose) acid secretion. Neither diltiazem nor cinnarizine modified gastric acid secretion in this experimental model. These findings are discussed in relation to the role of extracellular calcium in gastric motility and secretion, and the existence of a regional and functional selectivity for calcium blockers is proposed.