Ranitidine: dose and precautions

Ranitidine is a specific and fast-acting antihistamine drug. Inhibits gastric acid secretion, both stimulated and basal. In this way, ranitidine reduces the volume and acid and pepsin content of the secretion.

Its effects have a fairly long duration. Therefore, a single dose of 150 mg can effectively reduce gastric acid secretion for 12 hours. What else should you know about it? Coming up next, we tell you.

Knowing a little about the history of ranitidine

This medicine was developed by the pharmaceutical company Glaxo from another antihistamine, the first one they developed, cimetidine. In this way, ranitidine was the result of a design process. The researchers wanted to refine the chemical model by replacing different chemical groups.

With these tests they managed to synthesize ranitidine, which has a much better tolerance profile. That is, the symptomatic picture related to adverse reactions to the drug is much lower.

In turn, it has a longer action and an activity 4 to 10 times greater than that of cimetidine. In 1981 it is launched to the market and It was the most sold prescription in 1988. Since then, it has been replaced by more effective drugs for indications.

Ranitidine was the result of a design process by the pharmaceutical company Glaxo.

What is histamine?

Histamine is a substance that belongs to the chemical family of idazólica amines, which are involved in local immune system responses. It also regulates normal functions in the stomach and acts as a neurotransmitter in the central nervous system.

Neurotransmitters are substances that the body synthesizes naturally and whose main function is to modulate the synapse between neurons. In other words, they regulate chemical interactions between neurons when transmitting signals.

In this way, we make the electrical connections become more complete and give rise to many more possibilities. If neurotransmitters did not exist and neurons acted as simple "wires," it would not be possible to perform many of the functions of the nervous system.

On the other hand, there is new evidence indicating that histamine also plays a role in chemotaxis of white blood cells, such as eosinophils.

Since the 50s it is known about the existence of histamine. But nevertheless, it is very recently when they began to know their functions in the body.


The indications of this medicine are related to their ability to antagonize H2 receptors of histidine. Among them we can mention:

  • Duodenal ulcer
  • Benign Gastric Ulcer:
  • Gastroesophageal reflux and treatment of associated symptoms.
  • Zollinger-Ellison syndrome.
  • Treatment of esophageal and gastric hemorrhage with hypersecretion and prophylaxis of recurrent bleeding in patients with bleeding ulcer.

In addition to those mentioned, ranitidine is also used as prophylaxis of gastrointestinal bleeding caused to a stress ulcer in seriously ill.

Also, in the preoperative given to patients at risk of acid aspiration syndrome, which is known as Mendelson syndrome. It is also given in obstetric patients during childbirth.

Also read: 6 foods you should eat if you have stomach ulcers

Dosage and dose

The form of administration of ranitidine is orally. If this route cannot be used, there are ampoules for administration in intravenous infusion or intramuscular route. However, this type of administration will be done in the hospital setting.

Depending on the indication for which ranitidine has been indicated, concentrations will vary:

  • Duodenal ulcer in adults: A dose of 150 mg is administered every 12 hours or 300 mg overnight for 4-6 weeks. In children, 2 mg per kilogram of the child's weight every 12 hours.
  • Gastric ulcer in adults: 150 mg every 12 hours or 300 mg at night for 6-8 weeks. For the associated symptoms, 150 mg is administered every 12 hours for two weeks, and the treatment may be extended due to a poor initial response to it.
  • Zollinger-Ellison syndrome: The initial dose will be 150 mg every 8 hours. It can be increased according to the patient's response. However, the maximum dose of this drug is 6 grams per day.

For the other indications You have to check with the medicine's data sheet, in which all the information related to ranitidine is collected.

Precautions for use of ranitidine

Before using ranitidine it is important to pay attention to its possible side effects and contraindications.

For the use of ranitidine caution must be taken in a series of situations andn the dose should be adjusted to avoid serious complications. This is the case of patients who present some of the following problems:

  • Renal impairment: dose should be adjusted.
  • Interference in the diagnosis of carcinoma: ranitidine can delay the symptoms of this type of cancer which masks the diagnosis.
  • Interference in diagnostic tests.
  • Pregnancy and breastfeeding

Discover: Exercises to reduce swelling of the feet in pregnancy


Ranitidine is an antihistamine drug widely used under medical prescription. The doctor's recommendations for use should be followed since it is not absent of adverse effects and can produce a series of complications.