COMPOSITION :
Equivalent to Rabeprazole(As enteric coated pellets)
Domperidone(As sustained release pellets)
DESCRIPTION :
Rabeprazole belongs to a class of antisecretory compounds (substituted benzimidazole proton-pump inhibitors) that do not exhibit anticholinergic or
histamine H2 -receptor antagonist properties, but suppress gastric acid secretion by inhibiting the gastric H+/K + ATPase at the secretory surface of the
gastric parietal cell. Because this enzyme is regarded as the acid (proton) pump within the parietal cell, rabeprazole has been characterized as a gastric
proton pump inhibitor. Rabeprazole blocks the final step of gastric acid secretion. In gastric parietal cells, rabeprazole is protonated, accumulates, and is
Domperidone is a derivative of benzimidazole that possesses both prokinetic and antiemetic properties due to its inhibitory action at dopamine D2
PHARMACOLOGY : Pharmacodynamics: Mechanism of Action Rabeprazole
Rabeprazole belongs to a class of antisecretory compounds (substituted benzimidazole proton-pump inhibitors) that do not exhibit anticholinergic or
histamine H2-receptor antagonist properties, but suppress gastric acid secretion by inhibiting the gastric H+, K+ ATPase at the secretory surface of the
gastric parietal cell. Because this enzyme is regarded as the acid (proton) pump within the parietal cell, rabeprazole has been characterized as a gastric
proton-pump inhibitor. Rabeprazole blocks the final step of gastric acid secretion. In gastric parietal cells, rabeprazole is protonated, accumulates, and is
transformed to an active sulfenamide.
When studied in vitro, rabeprazole is chemically activated at pH 1.2 with a half-life of 78 seconds. It inhibits acid transport in porcine gastric vesicles with
Antisecretory Activity
The antisecretory effect begins within one hour after oral administration of 20 mg rabeprazole. The median inhibitory effect of rabeprazole on 24 hour
gastric acidity is 88% of maximal after the first dose. Rabeprazole 20 mg inhibits basal and peptone meal-stimulated acid secretion versus placebo by
86% and 95%, respectively, and increases the percent of a 24-hour period that the gastric pH>3 from 10% to 65% (see table below). This relatively
prolonged Pharmacodynamics action compared to the short pharmacokinetic half-life (1-2 hours) reflects the sustained inactivation of the H+, K+
Domperidone
Domperidone is a dopamine antagonist with anti-emetic properties domperidone does not readily cross the blood-brain barrier. In domperidone users,
especially in adults, extrapyramidal side effects are very rare, but domperidone promotes the release of prolactin from the pituitary. Its anti-emetic effect
may be due to a combination of peripheral (gastrokinetic) effects and antagonism of dopamine receptors in the chemoreceptor trigger zone, which lies
outside the blood-brain barrier in the area postrema. Animal studies, together with the low concentrations found in the brain, indicate a predominantly
peripheral effect of domperidone on dopamine receptors. Studies in man have shown oral domperidone to increase lower esophaegeal pressure,
improve antroduodenal motility and accelerate gastric emptying. There is no effect on gastric secretion. Pharmacokinetics: Rabeprazole
After oral administration of 20 mg rabeprazole, peak plasma concentrations (Cmax) of rabeprazole occur over a range of 2.0 to 5.0 hours (Tmax). The
rabeprazole C max and AUC are linear over an oral dose range of 10 mg to 40 mg. There is no appreciable accumulation when doses of 10 mg to 40 mg
are administered every 24 hours; the pharmacokinetics of rabeprazole is not altered by multiple dosing. The plasma half-life ranges from 1 to 2 hours. Absorption
Absolute bioavailability for a 20 mg oral tablet of rabeprazole (compared to intravenous administration) is approximately 52%. Rabeprazole may be taken
Distribution
Rabeprazole is 96.3% bound to human plasma proteins. Metabolism
Rabeprazole is extensively metabolized. The thioether and sulphone are the primary metabolites measured in human plasma. In vitro studies have
demonstrated that rabeprazole is metabolized in the liver primarily by cytochromes P450 3A (CYP3A) to a sulphone metabolite and cytochrome P450
2C19 (CYP2C19) to desmethyl rabeprazole.The thioether metabolite is formed non-enzymatically by reduction of rabeprazole. Excretion
Following a single 20 mg oral dose of 14 C-labeled rabeprazole, approximately 90% of the drug was eliminated in the urine, primarily as thioether
carboxylic acid; its glucuronide, and mercapturic acid metabolites. The remainder of the dose was recovered in the feces. No unchanged rabeprazole
Domperidone Absorption
In fasting subjects, domperidone is rapidly absorbed after oral administration, with peak plasma concentrations at 30 to 60 minutes. The low absolute
bioavailability of oral domperidone (approximately 15%) is due to an extensive first-pass metabolism in the gut wall and liver. Although domperidone`s
bioavailability is enhanced in normal subjects when taken after a meal, patients with gastro-intestinal complaints should take domperidone 15-30
minutes before a meal. Reduced gastric acidity impairs the absorption of domperidone. Oral bioavailability is decreased by prior concomitant
administration of cimetidine and sodium bicarbonate. The time of peak absorption is slightly delayed and the AUC somewhat increased when the oral
Distribution :
Oral domperidone does not appear to accumulate or induce its own metabolism; a peak plasma level after 90 minutes of 21 ng/ml after two weeks oral
administration of 30 mg per day was almost the same as that of 18 ng/ml after the first dose. Domperidone is 91-93% bound to plasma proteins.
Distribution studies with radiolabelled drug in animals have shown wide tissue distribution, but low brain concentration. Small amounts of drug cross
Metabolism
Domperidone undergoes rapid and extensive hepatic metabolism by hydroxylation and N-dealkylation. In vitro metabolism experiments with diagnostic
inhibitors revealed that CYP3A4 is a major form of cytochrome P-450 involved in the N-dealkylation of domperidone, whereas CYP3A4, CYP1A2 and
CYP2E1 are involved in domperidone aromatic hydroxylation. Excretion
Urinary and fecal excretions amount to 31 and 66% of the oral dose respectively. The proportion of the drug excreted unchanged is small (10% of fecal
excretion and approximately 1% of urinary excretion). The plasma half-life after a single oral dose is 7-9 hours in healthy subjects but is prolonged in
patients with severe renal insufficiency.
INDICATIONS :
RAZOCER-DSR is indicated for the relief of symptoms of
3. Nausea associated with acid peptic disorders.
DOSAGE AND ADMINISTRATION :
One capsule a day or as directed by the physician.
CONTRAINDICATIONS :
RAZOCER-DSR is contraindicated in patients with known hypersensitivity to rabeprazole, substituted benzimidazole, Domperidone or to any component
of the formulation. It should not be used whenever stimulation of gastric motility is to be avoided or could be harmful, e.g. in the presence of gastro-
intestinal hemorrhage, obstruction or perforation. It is also contra-indicated in patients with a prolactin-releasing pituitary tumor (prolactinoma).
ADVERSE EFFECTS :
Adverse effects with rabeprazole are mild to moderate in intensity and included malaise, diarrhea, nausea, skin eruptions, headache and dizziness.
Abnormal laboratory findings (increased hepatic enzymes, LDH, blood urea nitrogen) observed with rabeprazole were similar in incidence and severity
with comparator agents and reversible with cessation of therapy.
Domperidone has been found to be associated with increased serum prolactin, which may be associated with galactorrhea, less frequently
gynaecomastia, breast enlargement and soreness. Reduced libido has been reported. Occasional rashes and other allergenic phenomena are also
reported. Domperidone does not readily cross the normally functioning blood brain barrier and is therefore less likely to interfere with the central
dopaminergic function. However, acute extrapyramidal dystonic reactions have been reported with domperidone.
SHELF-LIFE : PACKAGING INFORMATION :
RAZOCER- DSR is available in an Alu - Alu pack of 10 capsules.
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