Astac competitively blocks histamine at H2-receptors of the gastric parietal cells which inhibits gastric acid secretion. It does not affect pepsin secretion, pentagastrin-stimulated intrinsic factor secretion or serum gastrin.
Astac is used for:
- Treatment of active duodenal ulcer
- Benign gastric ulcer
- Treatment & prevention of ulcer associated with non-steroidal anti-inflammatory agent
- Post operative stress ulcer.
- Zollinger-Ellison Syndrome.
- Gastroesophageal reflux disease (GERD).
- Gastro-intestinal haemorrhage from stress ulcer in seriously ill patient.
- Recurrent haemorrhage in patients with bleeding peptic ulcer.
- Before general anesthesia in patient considered to be at risk of acid aspiration particulary obstetric patients.
Astac is also used to associated treatment for these conditions: Acid Aspiration Syndrome, Ankylosing Spondylitis (AS), Duodenal Ulcer, Erosive Esophagitis, Gastric Ulcer, Gastric hypersecretion, Gastro-esophageal Reflux Disease (GERD), Healing, Heartburn, Osteoarthritis (OA), Peptic Ulcer Disease, Rheumatoid Arthritis, Stress Ulcers, Zollinger-Ellison Syndrome, Active duodenal ulcers, Benign gastric ulcer healing, Benign gastric ulcers, Duodenal ulcer healing, Post-operative peptic ulcer, Recurrent hemorrhage from bleeding ulcers
|Other Names||Ranitidina, Ranitidine, Ranitidinum|
The plasma protein binding of ranitidine is approximately 15%.
|Therapeutic Class||H2 receptor antagonist|
|Manufacturer||Astra Biopharmaceuticals Ltd|
|Last Updated:||June 23, 2021 at 11:25 am|
Table Of contents
Astac Tablet & Syrup:
Duodenal and gastric ulcer: The usual dosage is 150 mg twice daily taken in the morning and evening or 300 mg as a single daily dose at night for 4 to 8 weeks.
Reflux oesophagitis: 150 mg twice daily or 300 mg at bed time for up to 8 weeks.
Zollinger Ellison syndrome: 150 mg 3 times daily and increased if necessary up to 6 g daily in divided doses. Dosage should be continued as long as clinically indicated.
Episodic dyspepsia: 150 mg twice daily or 300 mg at bed time for up to 6 weeks.
Maintenance: 150 mg at night for preventing recurrences.
Child (peptic ulcer)
Astac IV injection & IV Infusion:
Astac injection may be given either as a slow (over a period of at least two minutes) intravenous injection of 50 mg, after dilution to a volume of 20 ml per 50 mg dose, which may be repeated every six to eight hours; or as an intermittent intravenous infusion at a rate of 25 mg per hour for two hours; the infusion may be repeated at six to eight hour intervals; or as an intramuscular injection of 50 mg (2 ml) every six to eight hours. In the prophylaxis of haemorrhage from stress ulceration in seriously ill patients or the prophylaxis of recurrent haemorrhage in patients bleeding from peptic ulceration, parenteral administration may be continued until oral feeding commences.: 2-4 mg/kg twice daily, maximum 300 mg daily.
In the prophylaxis of upper gastrointestinal haemorrhage from stress ulceration in seriously ill patient sapriming dose of 50 mg as low as intravenous injection followed by a continuous intravenous infusion of 0.125-0.250 mg/kg/hour may be preferred. In patients considered to be at risk of developing aspiration syndrome Astac injection 50 mg may be given intramuscularly or by slow intravenous injection 45 to 60 minutes before induction of general anaesthesia.
Children: The recommended oral dose for the treatment of peptic ulcer in children is 2 mg/kg to 4 mg/kg twice daily to a maximum of 300 mg ranitidine per day. Safety and effectiveness of Astac injection have not been established in case of children.
Slow IV inj: Astac 50 mg diluted to a concentration ≤2.5 mg/mL (e.g. total of 20 mL) with NaCl 0.9% inj or dextrose 5% or 10%, lactated Ringer's, Na bicarbonate 5% soln.
Intermittent slow IV infusion: Astac 50 mg diluted to a concentration ≤0.5 mg/mL (e.g. total of 100 mL) of dextrose 5% inj or NaCl 0.9%, lactated Ringer's, Na bicarbonate 5% soln.
Continuous IV infusion: Astac 150 mg diluted in 250 mL of dextrose 5% inj or NaCl 0.9%, lactated Ringer's, Na bicarbonate 5% soln.
Patients with Zollinger-Ellison syndrome or other hypersecretory conditions: Astac should be diluted to a concentration ≤2.5 mg/mL with dextrose 5% or NaCl 0.9%, lactated Ringer's, Na bicarbonate 5% soln.
Astac is well tolerated and side effects are usually uncommon. Altered bowel habit, dizziness, rash, tiredness, reversible confusional states, headache, decreased blood counts, muscle or joint pain have rarely been reported.
Astac should be given in reduced dosage to patients with impaired renal and hepatic function.
Delayed absorption and increased peak serum concentration with propantheline bromide. Astac minimally inhibits hepatic metabolism of coumarin anticoagulants, theophylline, diazepam and propanolol. May alter absorption of pH-dependent drugs (e.g. ketoconazole, midazolam, glipizide). May reduce bioavailability with antacids.
- Take with or without food. The absorption is unaffected by food.
Volume of Distribution
The volume of distribution is higher than body volume, and measures at approximately 1.4 L/kg. It concentrates in breast milk, but does not readily distribute into the cerebrospinal fluid.
The elimination half-life or ranitidine is about 2.5-3 hours. It may be longer after oral administration versus injection. The plasma half-life is longer for elderly patients population due to a decrease in renal function, and is measured at 3-4 hours.
Renal clearance is about 410 mL/min according to FDA prescribing information. Another resource mentions a plasma clearance of approximately 600 ml/min. Clearance is decreased in the elderly and those with impaired or hepatic renal function. It is recommended to decrease the dose of ranitidine by one-half in patients with renal impairment.
Pregnancy & Breastfeeding use
Pregnancy: Astac crosses the placenta. But there is no evidence of impaired fertility or harm to the foetus due to Astac. Like other drugs, Astac should only be used during pregnancy if considered essential.
Lactation: Astac is excreted in human breast milk. Caution should be exercised when the drug is administered to a nursing mother.
Patients hypersensitive to Astac
Use in elderly patients: In clinical trial the ulcer healing rates have been found similar in patients age 65 and over with those in younger patients. Additionally, there was no difference in the incidence of adverse effects.
Astac is very specific in action and accordingly no particular problems are expected following overdosage with the drug. Symptomatic and supportive therapy should be given as appropriate. If required, the drug may be removed from the plasma by haemodiaiysis.
Store in a cool and dry place. protect from light.