DESCRIPTION
Ranitidine-A non-imidazole blocker of those histamine receptors that mediate gastric secretion (H2 receptors). It is used to treat gastrointestinal ulcers. Domperidone-A specific blocker of dopamine receptors. It speeds gastrointestinal peristalsis, causes prolactin release, and is used as antiemetic and tool in the study of dopaminergic mechanisms.
CATEGORIES
Ranitidine-Anti-Ulcer Agents, Histamine H2 Antagonists. Domperidone-Antiemetics, GIT Regulators & Anti-Inflammatories.
CHEMICAL FORMULA
Ranitidine-C13H22N4O3S.Domperidone-C22H24ClN5O2.
COMPOSITION
Ranitidine 150 mg+Domperidone 10 mg
INDICATION
Ranitidine-Used in the treatment of peptic ulcer disease (PUD), dyspepsia, stress ulcer prophylaxis, and gastroesophageal reflux disease (GERD).Domperidone-For management of dyspepsia, heartburn, epigastric pain, nausea, and vomiting.
PHARMACODYNAMICS
Ranitidine-Ranitidine is a histamine H2-receptor antagonist similar to cimetidine and famotidine. An H2-receptor antagonist, often shortened to H2 antagonist, is a drug used to block the action of histamine on parietal cells in the stomach, decreasing acid production by these cells. These drugs are used in the treatment of dyspepsia, however their use has waned since the advent of the more effective proton pump inhibitors. Like the H1-antihistamines, the H2 antagonists are inverse agonists rather than true receptor antagonists. Domperidone-Domperidone is a specific blocker of dopamine receptors. It speeds gastrointestinal peristalsis, causes prolactin release, and is used as antiemetic and tool in the study of dopaminergic mechanisms.
MECHANISM
Ranitidine-The H2 antagonists are competitive inhibitors of histamine at the parietal cell H2 receptor. They suppress the normal secretion of acid by parietal cells and the meal-stimulated secretion of acid. They accomplish this by two mechanisms: histamine released by ECL cells in the stomach is blocked from binding on parietal cell H2 receptors which stimulate acid secretion, and other substances that promote acid secretion (such as gastrin and acetylcholine) have a reduced effect on parietal cells when the H2 receptors are blocked.Domperidone-Domperidone acts as a gastrointestinal emptying (delayed) adjunct and peristaltic stimulant. The gastroprokinetic properties of domperidone are related to its peripheral dopamine receptor blocking properties. Domperidone facilitates gastric emptying and decreases small bowel transit time by increasing esophageal and gastric peristalsis and by lowering esophageal sphincter pressure. Antiemetic: The antiemetic properties of domperidone are related to its dopamine receptor blocking activity at both the chemoreceptor trigger zone and at the gastric level. It has strong affinities for the D2 and D3 dopamine receptors, which are found in the chemoreceptor trigger zone, located just outside the blood brain barrier, which – among others – regulates nausea and vomiting
ABSORPTION
Ranitidine-Approximately 50% bioavailability orally. Domperidone-Fast.
VOLUME DISTRIBUTION
Ranitidine-1.4 L/kg, 1.76 L/kg [clinically significant renal function impairment (creatinine clearance 25 to 35 mL/min)].
METABOLISM
Ranitidine-Hepatic. Ranitidine is metabolized to the N-oxide, S-oxide, and N-desmethyl metabolites, accounting for approximately 4%, 1%, and 1% of the dose, respectively.
ELIMINATION
Ranitidine-The principal route of excretion is the urine (active tubular excretion, renal clearance 410mL/min), with approximately 30% of the orally administered dose collected in the urine as unchanged drug in 24 hours.
HALF LIFE
Ranitidine-2.8-3.1 hours.Domperidone-7 hours.
TOXICITY
Ranitidine-LD50=77mg/kg (orally in mice). Symptoms of overdose include muscular tremors, vomiting, and rapid respiration.Domperidone-Side effects include galactorrhea, gynecomastia, or menstrual irregularities.
FOOD INTERACTIONS
Ranitidine-Avoid alcohol. Avoid excessive quantities of coffee or tea (Caffeine). Avoid milk, calcium containing dairy products, iron, antacids, or aluminum salts 2 hours before or 6 hours after using antacids while on this medication. Take without regard to meals.Domperidone-Take 15 to 30 minutes before meals.
SIDE EFFECTS
Ranitidine-Feeling dizzy. Rise slowly over a few minutes when sitting or lying down. Be careful climbing. Headache. Hard stools (constipation). Drinking more liquids, working out, or adding fiber to your diet may help. Talk with your doctor about a stool softener or laxative. Loose stools (diarrhea).Domperidone-Headache. Dry mouth. Good mouth care, sucking hard, sugar-free candy, or chewing sugar-free gum may help. See a dentist often.