Effect of Pantoprazole and Its Interactions with Vecuronium on the Neuromuscular Junction

Research Article

Effect of pantoprazole and its interactions with vecuronium on the neuromuscular junction

Tejas K. Patel, Parvati B. Patel, C.B. Tripathi

ABSTRaCT

Objective: To study the effect of pantoprazole on neuromuscular transmission and its interactions with vecuronium at the neuromuscular junction (NMJ). Materials and Methods: Effect of pantoprazole on neuromuscular transmission (2 µM – 16 mM) and reversal of neuromuscular blockade by pantoprazole and vecuronium Department of Pharmacology, with neostigmine (3.3 µM), 3,4-diaminopyridine (0.25 mM), KCl (6 mM), and CaCl (10 Government Medical College, 2 Bhavnagar, Gujarat, India mM) were studied by the indirect and direct stimulated preparation of rat phrenic nerve hemidiaphragm. Cumulative reponse curves (CRC) of vecuronium (1 µM to 32 µM) were Received: 04-05-2009 studied in the absence and presence of 32 µM, 64 µM, and 128 µM pantoprazole. Time Revised: 01-07-2009 for head drop by vecuronium infusion was recorded in the absence and presence of acute Accepted: 03-02-2010 and chronic administration of pantoprazole (1.9 mg/kg) in rabbits. Results: Pantoprazole potentiated the basal contractile twitch responses at a lower DOI: 10.4103/0253-7613.62410 concentration followed by neuromuscular blockade at a higher concentration. The neuromuscular blockade was not reversed by neostigmine (3.3 µM), 3,4-diaminopyridine

Correspondence to: (0.25 mM), KCl (6 mM), and CaCl2 (10 mM). Pantoprazole potentiated the vecuronium- Dr. C.B. Tripathi induced neuromuscular blockade. It decreased the total time for complete blockade in E-mail: [email protected] rat phrenic nerve hemidiaphragm preparation (P < 0.05) and decreased the time for the head drop in rabbits with vecuronium infusion (P < 0.0001). Conclusion: Pantoprazole has a direct neuromuscular blocking action. It has the potential to interact with vecuronium.

Key words: Drug interaction, neuromuscular junction, pantoprazole, vecuronium

Introduction proportion of patients at risk of significant lung injury.[10-12] Neuromuscular blocking drugs are agents that promote Proton pump inhibitors (PPIs) are widely used in modern skeletal muscle relaxation and are administered routinely for medicine. They are the most effective antisecretory drugs tracheal intubation, during abdominal surgery, for orthopedic available for controlling gastric acid acidity and volume in manipulation, and brief procedures such as laryngoscopy, the treatment of moderate-to-severe gastroesophageal reflux bronchoscopy, and esophagoscopy. Effects of H2-receptor disease, a hypersecretory state such as the Zollinger-Ellison antagonists, cimetidine, ranitidine, and roxatidine have been syndrome, peptic ulcers, NSAID-induced ulcers, and eradication documented on neuromuscular transmission. Cimetidine [1-3] of Helicobacter pylori (H. pylori) with two antibiotics. potentiates the neuromuscular action of gallamine[13] and Pantoprazole provides earlier healing and superior pain relief in succinylcholine[14] in vivo, in rats. In contrast, ranitidine reverses peptic ulcer and gastroesophageal reflux disease as compared the action of gallamine,[15] but produces an effect similar to [4,5] [16] to omeprazole and H2 receptor antagonists. Aspiration cimetidine against succinylcholine. Roxatidine delays the pneumonitis is a recognized postoperative complication of onset and decreases the total time for the compete block of anesthesia, which is associated with high morbidity and vecuronium in rats.[17] Famotidine has been shown to have mortality.[6,7] It is caused by aspiration of gastric contents, of a negligible effect on neuromuscular transmission.[18] PPIs pH below 2.5, with a volume exceeding 0.4 ml/kg.[8] PPIs are are substituted benzimidazoles that resemble H2-receptor an effective preanesthetic medication to reduce gastric acid antagonists in structure, but have a completely different secretion and to prevent aspiration pneumonitis intra- and mechanism for antisecretory action.[19] In case of PPIs, there postoperatively.[9] Intravenous pantoprazole, administered are documented effects of omeprazole[20] and lansoprazole[21] one hour before surgery, is useful in decreasing the volume on neuromuscular transmission, but limited information is and increasing the pH of gastric contents, thus reducing the available on the actual mechanism. No such information is

36 Indian J Pharmacol | Feb 2010 | Vol 42 | Issue 1 | 36-39 Patel, et al.: Interactions of pantoprazole and vecuronium on neuromuscular junction available for the effect of pantoprazole on neuromuscular Effect of pantoprazole on neuromuscular transmission: transmission. In patients who receive PPIs as a premedication Group 1: Cumulative response curve (CRC) of pantoprazole (2 and chronically for the treatment of peptic ulcer, there is a µM to 16 mM) in the indirectly stimulated preparation. potential for interaction with the neuromuscular blocking Group 2: CRC of pantoprazole (2 µM to 16 mM) in the directly drugs. This interaction would be clinically relevant because of stimulated preparation. respiratory depression and prolonged apnea. Interaction between pantoprazole and vecuronium: The present study is designed to elucidate the mechanism Group 3: CRC of vecuronium (1 µM to 32 µM) in the absence of of action of pantoprazole on neuromuscular transmission and pantoprazole in the indirectly stimulated preparation. its potential for interaction with the competitive neuromuscular Group 4: CRC of vecuronium (1 µM to 32 µM) in the presence blocker, vecuronium, using the isolated phrenic nerve of 32 µM pantoprazole in the indirectly stimulated hemidiaphragm preparation of rat and rabbit head drop method. preparation. Materials and Methods Group 5: CRC of vecuronium (1 µM to 32 µM) in the presence of 64 µM pantoprazole in the indirectly stimulated All the experiments were performed after prior permission preparation. from the Institutional Animal Ethics Committee, Government Group 6: CRC of vecuronium (1 µM to 32 µM) in the presence Medical College, Bhavnagar (Gujarat). of 128 µM pantoprazole in the indirectly stimulated Experimental animals: Male albino rats of Wistar strain preparation. (200 to 300 gms) and New Zealand white rabbits (1 – 1.5 kg) The following parameters were studied for all: of either sex were procured from the central animal house a) Time of onset for blockade of the institute. They were housed in standard polypropylene b) Total time for complete blockade and stainless steel cages, respectively, under controlled room c) IC for each drug. temperature (24 ± 20C) and relative humidity (60 – 70%) in 50 a 12 hour light–dark cycle. The rats were given the standard Percentage of block was obtained by: laboratory diet and water ad libitum. Food was withdrawn 12 twitch height in pretreated - twitch height in treated hours before the experiments. twitch height in pretreated The inhibitory concentration 50% (IC ) values of each drug Drugs used: The following drugs were used in the study: 50 pantoprazole sodium (Mankind Pharma Ltd., New Delhi, India), were calculated from the cumulative response curve (CRC), by vecuronium bromide (Neon Laboratories Ltd., Mumbai, India), regression analysis. neostigmine methylsulfate (Hindustan Pharmaceuticals, India), Reversal of neuromuscular blockade by vecuronium and 3,4-diaminopyridine (Alfa Aesar, Lancaster). pantoprazole: Pantoprazole sodium and vecuronium powder were Effects of neostigmine (3.3 µM), 3,4-diaminopyridine (0.25 dissolved in normal saline and distilled water, respectively, mM), potassium chloride - KCl (6 mM), and calcium chloride - and appropriate dilutions were made in the physiological salt CaCl2 (10 mM) on both vecuronium (10 µM)- and pantoprazole solution. Neostigmine ampules (0.5 mg/ml) were used as such. 4.0 mM)-induced paralysis were studied. 3,4-diaminopyridine was dissolved in distilled water. Stock Rabbit head drop method: The procedure of the rabbit solutions were stored in the refrigerator and dilutions were head drop method was followed as described by Verny.[23] The made from the stock solutions, as required, immediately before marginal ear vein was used for infusion of vecuronium (5 µg/ the study commenced. ml). The solution was infused from a 10 ml glass syringe fitted Isolated rat phrenic nerve hemidiaphragm preparation: to a slow injector (INCO Biodevice, Ambala), which was adjusted After sacrificing the rat, the phrenic nerve diaphragm was for a speed of 1 inch every 10 minutes. After standardization dissected out by opening the thoracic and abdominal wall, just of the technique, three groups of rabbits, consisting of six below the diaphragm, on the left side, and mounted as described animals per group were used. In each group, time for the head by Bulbring.[22] The preparation was set up in an organ bath drop (muscle supporting the head become sufficiently relaxed containing 40 ml of tyrode with double glucose salt solution to prevent the head to be raised when the back is stimulated) of the following composition (mM/liter): NaCl 136.9, KCl 2.68, after the infusion of vecuronium was recorded. Neostigmine (0.25 mg/kg) along with atropine (2 mg) was used to reverse CaCl2 1.36, MgCl2 0.98, NaH2PO4 0.32, and glucose 11.1. It was maintained at 37 ± 0.50C and aerated with oxygen. the effect of vecuronium after the head drop. Each preparation was allowed to equilibrate for 45 – 60 Group 1: Used as control and received the infusion of minutes under the resting tension of 1 – 2 g, to obtain the stable vecuronium basal conditions. The preparation was stimulated indirectly (2 V) Group 2: (acute study group): received intravenous through the phrenic nerve and directly (20 V) with square wave pantoprazole (1.9 mg/kg) 30 minutes before the pulses of 0.5 msec, for a duration of 0.5 Hz with a physiograph infusion of vecuronium stimulator. For direct stimulation only the diaphragm was Group 3: (chronic study group): received pantoprazole (1.9 mounted and the resulting isometric muscle contractions were mg/kg) orally for 15 days before the infusion of quantified with a forced displacement transducer and recorded on vecuronium a student physiograph (INCO Biodevice, Ambala) through a strain Statistical analysis: Results were expressed as a mean ± gauge coupler. The contact time for each drug was five minutes. SEM. The unpaired t-test was used to compare the difference Six preparations were used for each set of experiments. After in the cumulative response curves of pantoprazole in indirect stabilization, the following sets of experiments were performed: and direct stimulation. One way ANOVA followed by Dunnett’s

Indian J Pharmacol | Feb 2010 | Vol 42 | Issue 1 | 36-39 37 Patel, et al.: Interactions of pantoprazole and vecuronium on neuromuscular junction multiple comparisons was used to analyze the different significant reduction in the time for complete block. No significant concentrations of pantoprazole on vecuronium-induced difference was found for time of onset for block and IC50 of blockade. One way ANOVA was used to compare the three vecuronium in the presence of pantoprazole [Table 1]. groups in the rabbit head drop method. Effect of neostigmine, 3,4-diaminopyridine, potassium chloride, and calcium chloride on vecuronium- and Results pantoprazole-induced paralysis in the indirectly stimulated Rat phrenic nerve hemidiaphragm preparation: preparation: Partial blockade of the basal contractile twitch Effect of pantoprazole on indirect and direct responses of vecuronium (10 µM) was reversed by neostigmine stimulation: Pantoprazole (2 µM to 16.0 mM) produced (3.3 µM), potassium chloride (6 mM), and 3,4- diaminopyridine biphasic response on rat phrenic nerve hemidiaphragm (0.25 mM), but not by calcium chloride (10 mM). Partial blockade preparation. There was an enhancement of basal contractile of the basal contractile twitch responses of pantoprazole twitch response at the lower doses followed by blockade (4 mM) was not reversed by neostigmine (3.3 µM), potassium at higher doses with both indirect and direct stimulation chloride (6 mM), 3,4- diaminopyridine (0.25 mM), and calcium [Figure 1]. There was no significant difference in the time of chloride (10 mM). onset of the block (48.80 ± 1.56 and 44.44 ± 3.28 minutes), Rabbit Head Drop Method complete block (64.69 ± 1.56 and 64.36 ± 1.29 minutes), and Time for the rabbit head drop after vecuronium infusion in

IC50 (4.11 ± 0.23 and 3.89 ± 0.16 log dose) of pantoprazole the control, acute, and chronic study groups was: 4.74 ± 0.23, paralysis in case of indirect and direct stimulations (Unpaired 1.99 ± 0.33, and 1.73 ± 0.13 minutes, respectively. Both acute t-test: P > 0.05). and chronic administration of pantoprazole significantly reduced Interaction of pantoprazole and vecuronium in the it, as compared to the control group (P < 0.001). However, the indirectly stimulated preparation: Cumulative response significant difference in time for head drop between acute and curves of vecuronium (2 µM to 16 mM) were taken in the chronic study groups was statistically insignificant (Tukey’s absence and presence of three different concentrations of multiple comparison test). pantoprazole (32 µM, 64 µM, and 128 µM) in indirectly stimulated preparations. Time of onset for block, time for complete block, Discussion and IC50 of vecuronium were compared between the control There is evidence of the occurrence of interaction between and pantoprazole groups. Quick skeletal muscle relaxation PPIs and neuromuscular blocking drugs. Omeprazole was achieved in the presence of pantoprazole, as shown by the intravenously, at therapeutic doses, alters neuromuscular

Figure 1: Effect of pantoprazole on the indirect and direct stimulation of rat phrenic nerve hemidiaphragm preparation Mean ± SEM has been shown (n = 6).

Table 1:

Effect of pantoprazole on vecuronium-induced blockade (Mean ± SEM, n = 6)

Vecuronium Time for onset of block (min) Time for complete block (min) IC50 (log dose) Control 6.71 ± 1.38 27.19 ± 0.84 1.08 ± 0.15 Pantoprazole (32 µM) 6.46 ± 1.57 23.74 ± 1.16* 0.73 ± 0.17 Pantoprazole (64 µM) 7.59 ± 1.35 23.51 ± 0.84* 0.85 ± 0.14 Pantoprazole (128 µM) 10.17 ± 0.18 23.14 ± 0.91* 0.88 ± 0.15 One way ANOVA F (df) 1.89 (3, 20) 4.66 (3, 20) 2.89 (9,117) P > 0.05 < 0.05 > 0.05

*P < 0.05 compared to the corresponding control (Dunnett’s multiple comparison Test). IC50-inhibitory concentration of vecuronium to produce 50% paralysis

38 Indian J Pharmacol | Feb 2010 | Vol 42 | Issue 1 | 36-39 Patel, et al.: Interactions of pantoprazole and vecuronium on neuromuscular junction function and enhances the action of atracurium and Gastroenterol 2001;32:27-32. succinylcholine in vivo in rats.[20] Lansoprazole potentiates 2. Vanderhoff BT, Tahboub RM. Proton pump inhibitor: An update. Am Fam Physician vecuronium-induced paralysis when used as a preanesthetic 2002;66:273-80. [21] 3. Shi S, Klotz U. Proton pump inhibitors: An update of their clinical use and medication. pharmacokinetics. Eur J Clin Pharmacol 2008;64:935-51. In the present study, pantoprazole has shown dual 4. Bardhan KD. Pantoprazole: A new proton pump inhibitor in the management of action, with the initial potentiation of the basal contractile upper gastrointestinal disease. Drugs Today 1999;35:773-808. twitch responses at lower doses followed by paralysis at 5. Fitton A, Wiseman L. 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