Ranidin150 mg

Ranidin 150 mg Hydrochloride is a histamine H2-receptor antagonist (H2 blocker) indicated for the treatment and prevention of a range of acid-related gastrointestinal disorders. It works by reducing gastric acid secretion, allowing the healing of acid-damaged mucosa and relieving acid-related symptoms. Ranidin 150 mg is indicated for the following conditions:

Duodenal Ulcer

Ranidin 150 mg is indicated for the short-term treatment of active duodenal ulcers — peptic ulcers involving the first part of the small intestine (duodenum). Most duodenal ulcers heal within 4 weeks of therapy. Ranidin 150 mg is also indicated for the maintenance therapy of healed duodenal ulcers at reduced doses to prevent relapse — a common problem with this condition.

Benign Gastric Ulcer

Ranidin 150 mg is indicated for the short-term treatment of active benign gastric ulcers (stomach ulcers not associated with malignancy). Most gastric ulcers heal within 6–8 weeks of Ranidin 150 mg therapy. Maintenance therapy at reduced doses is also indicated to reduce the frequency of gastric ulcer recurrence.

Gastroesophageal Reflux Disease (GERD)

Ranidin 150 mg is indicated for the treatment of gastroesophageal reflux disease (GERD) — a chronic condition characterized by the backward flow of stomach acid into the esophagus, causing heartburn, regurgitation, and esophageal irritation. It provides symptomatic relief and suppresses acid to promote mucosal healing in GERD.

Erosive Esophagitis

Ranidin 150 mg is indicated for the healing and maintenance of erosive esophagitis — a more severe form of GERD where the esophageal lining has been damaged by chronic acid exposure. After initial healing, maintenance therapy reduces the risk of recurrence of esophageal erosions.

Pathological Hypersecretory Conditions

Ranidin 150 mg is indicated for the long-term treatment of pathological hypersecretory conditions where the stomach produces excessive acid, including:

• Zollinger-Ellison Syndrome — a rare condition caused by gastrin-secreting tumors (gastrinomas) that stimulate massive gastric acid overproduction
• Systemic Mastocytosis — a disorder of abnormal mast cell proliferation with excessive histamine release
• Multiple Endocrine Adenomas
• Postoperative Hypersecretion and "short-gut" syndrome

Stress Ulcer Prophylaxis

Ranidin 150 mg injection is used in hospitalized patients, particularly in intensive care settings, to prevent stress-related gastric mucosal damage and upper GI bleeding in critically ill patients (including those on mechanical ventilation, with severe burns, major trauma, or following major surgery).

Anaphylaxis — Adjunctive Use

Intravenous Ranidin 150 mg may be used as an adjunct to epinephrine in the management of anaphylaxis for additional relief of histamine-mediated urticaria and hives. It should not be used as the primary or sole treatment of anaphylaxis, as it does not address airway obstruction or cardiovascular shock.

Ranidin 150 mg Hydrochloride is a competitive and reversible inhibitor of histamine action at the histamine H2-receptor, including those located on the basolateral membrane of gastric parietal cells. It belongs to the second generation of H2 blockers and offers greater potency and longer duration of action compared to cimetidine (the first H2 blocker).

Mechanism of Action

Gastric acid secretion by parietal cells is regulated by three primary stimulants — histamine, gastrin, and acetylcholine. Of these, histamine-mediated activation of H2 receptors plays the central and most important role:

1. Histamine released from enterochromaffin-like (ECL) cells in the gastric mucosa binds to H2 receptors on parietal cells.
2. H2 receptor activation stimulates adenylyl cyclase, raising intracellular cyclic AMP (cAMP), which activates protein kinase A.
3. This signalling cascade ultimately activates the H⁺/K⁺-ATPase proton pump, which pumps hydrogen ions into the gastric lumen in exchange for potassium ions — producing hydrochloric acid (HCl).

Ranidin 150 mg competitively and reversibly blocks H2 receptors on parietal cells, inhibiting histamine-stimulated acid secretion. By blocking H2 receptors, Ranidin 150 mg also indirectly reduces the amplifying effect of histamine on gastrin- and acetylcholine-stimulated acid secretion, producing a comprehensive reduction in acid output.

Pharmacological Properties

• Not an anticholinergic agent — Ranidin 150 mg does not block muscarinic receptors. It therefore does not produce the anticholinergic side effects associated with older agents (dry mouth, urinary retention, blurred vision, constipation).
• Does not lower serum calcium — Ranidin 150 mg does not affect serum calcium concentrations in hypercalcemic states.
• Reduces all phases of acid secretion — Ranidin 150 mg inhibits basal (fasting), nocturnal, and meal-stimulated acid secretion.
• Nocturnal acid suppression is particularly effective — a single dose at bedtime significantly reduces overnight acid output, which is especially important for duodenal ulcer healing (which is primarily driven by nocturnal acid secretion).
• Intrinsic factor — Ranidin 150 mg does not significantly reduce intrinsic factor secretion at therapeutic doses.

Pharmacokinetics

• Absorption: Oral Ranidin 150 mg is approximately 50% absorbed following oral administration — not significantly affected by food or antacids. Peak plasma concentrations (C_max) are achieved within 1 to 3 hours after an oral dose.
• Distribution: Widely distributed in body tissues, including gastric secretions, bile, semen, and breast milk. Plasma protein binding is approximately 15%. Volume of distribution is approximately 1.4 L/kg.
• Metabolism: Partially metabolized in the liver to N-oxide (primary metabolite), S-oxide, and desmethyl metabolites — all pharmacologically inactive or substantially less potent. Unlike cimetidine, Ranidin 150 mg has a much lower affinity for cytochrome P450 enzymes, producing fewer clinically significant drug interactions.
• Half-life: Approximately 2.5 to 3 hours in adults with normal renal function. Prolonged in patients with renal impairment and in elderly patients.
• Elimination: Primarily renal — approximately 30–35% of an oral dose (and approximately 70% of an IV dose) is excreted unchanged in the urine via both glomerular filtration and active tubular secretion. Because renal excretion is the primary route of elimination, dose adjustment is required in renal impairment.

Oral Tablets and Syrup

• Ranidin 150 mg tablets and syrup may be taken with or without food. Absorption is not significantly affected by food.
• Swallow tablets whole with a full glass of water. Do not crush or chew enteric-coated tablets.
• For liquid formulations, measure carefully using the provided dosing syringe or a calibrated measuring device — do not use a regular kitchen spoon.
• For once-daily dosing (maintenance therapy), the bedtime dose is preferred, as it most effectively suppresses nocturnal acid secretion — the primary driver of duodenal ulcer pathophysiology.
• Antacids may be used concurrently for immediate pain relief while waiting for Ranidin 150 mg to take effect; consult with your physician regarding timing.
• If GERD does not respond adequately after 6–8 weeks, do not increase the Ranidin 150 mg dose — consult your physician about switching to a proton pump inhibitor (PPI).
• Continue taking Ranidin 150 mg for the full prescribed duration, even if symptoms resolve early — healing requires continued acid suppression.

Intramuscular (IM) Injection

• Administer Ranidin 150 mg injection undiluted as a deep intramuscular injection into a large muscle mass.
• Rotate injection sites if multiple doses are required.
• IM administration may cause transient burning or pain at the injection site.

Intravenous (IV) Bolus Injection

• Dilute 50 mg Ranidin 150 mg in at least 20 mL of a compatible IV solution (0.9% Sodium Chloride, 5% Dextrose, or Ringer's Lactate) before injection.
• Inject slowly over at least 5 minutes at a rate not exceeding 4 mL/minute.
• Rapid IV injection must be avoided — it can cause bradycardia, hypotension, and cardiac arrhythmias.
• Inspect visually for particulate matter and discoloration before use. Discard if discolored or contaminated.

Intravenous (IV) Intermittent Infusion

• Dilute 50 mg Ranidin 150 mg in at least 100 mL of compatible IV solution (5% Dextrose or 0.9% Sodium Chloride) to achieve a concentration ≤0.5 mg/mL.
• Infuse over 15 to 20 minutes.

Intravenous (IV) Continuous Infusion

• For Zollinger-Ellison syndrome or stress ulcer prophylaxis: dilute 150 mg in 250 mL of 5% Dextrose and infuse at 6.25 mg/hour over 24 hours.
• Do not mix Ranidin 150 mg injection with other medications in the same IV bag without confirming compatibility.
• Switch to oral Ranidin 150 mg as soon as the patient can tolerate oral medications.

Ranidin 150 mg affects drug bioavailability through multiple mechanisms — primarily by altering gastric pH (affecting pH-dependent absorption) and by competing with other drugs for renal tubular secretion. Unlike cimetidine, Ranidin 150 mg has minimal inhibitory activity on hepatic cytochrome P450 enzymes at standard doses, making it a safer option in patients on multiple medications. However, the following interactions are clinically relevant:

Drugs with pH-Dependent Absorption — Reduced Efficacy

By raising intragastric pH, Ranidin 150 mg can reduce the oral absorption and efficacy of drugs that require an acidic environment for dissolution or absorption:

• Ketoconazole (oral): Ranidin 150 mg can reduce oral ketoconazole exposure by up to 95% at high doses maintaining gastric pH above 6. Even at the standard Ranidin 150 mg dose (150 mg twice daily), the interaction may be clinically significant. Alternative antifungal agents that are not pH-dependent should be considered.
• Itraconazole: Similarly reduced absorption in an elevated gastric pH environment.
• Erlotinib: Gastric pH elevation reduces erlotinib absorption, potentially compromising anti-cancer efficacy.
• Sparsentan: H2 antagonists may decrease sparsentan exposure — avoid combination or use alternative acid-reducing therapy.
• Atazanavir and Nelfinavir: Antiretroviral agents whose absorption is reduced by elevated gastric pH.

Midazolam and Triazolam (Benzodiazepines) — Increased Sedation

Oral Ranidin 150 mg 150 mg twice daily increased oral midazolam exposure by up to 65% and triazolam exposure by approximately 30% in clinical pharmacokinetic studies. The proposed mechanism includes both reduced gastric acid-mediated midazolam metabolism and possible inhibition of intestinal CYP3A4 at higher gastric pH. Monitor patients for excessive or prolonged sedation when Ranidin 150 mg is co-administered with oral benzodiazepines metabolized by CYP3A4. Note: the interaction was smaller (approximately 9% increase) with IV midazolam.

Warfarin — Enhanced Anticoagulant Effect

Ranidin 150 mg may increase the serum concentration of warfarin — likely through inhibition of warfarin metabolism (minor CYP2C9 inhibition at standard doses). There have been reported cases of increased INR and bleeding in patients on warfarin and Ranidin 150 mg. Monitor INR/prothrombin time when initiating, changing, or discontinuing Ranidin 150 mg in patients on warfarin therapy.

Procainamide — Increased Drug Levels

Ranidin 150 mg may reduce renal tubular secretion of procainamide (an antiarrhythmic agent), increasing its plasma concentration and potentially increasing the risk of procainamide toxicity (hypotension, arrhythmias, lupus-like syndrome). Monitor procainamide levels during concurrent use.

Antacids — Absorption Timing

Antacids may slightly reduce the rate (but not overall extent) of Ranidin 150 mg absorption. Antacids may be used concurrently for breakthrough pain relief, but should ideally be administered at different times (approximately 1–2 hours apart) from Ranidin 150 mg to minimize any reduction in Ranidin 150 mg absorption.

Sotorasib and Defactinib — Reduced Efficacy

Ranidin 150 mg may decrease the levels of sotorasib (a KRAS G12C inhibitor) and defactinib by increasing gastric pH, reducing their oral absorption and potentially compromising anti-cancer efficacy. Avoid concurrent use with these agents if possible; if unavoidable, follow specific timing guidelines as per current prescribing information.

Ranidin 150 mg is generally well tolerated at recommended doses. Most adverse effects are mild and transient. The following adverse effects have been reported across clinical trials, post-marketing surveillance, and routine clinical use:

Common Side Effects

• Headache — the most frequently reported adverse effect; sometimes severe but generally resolves with continued treatment
• Abdominal discomfort, nausea, and vomiting
• Constipation or diarrhoea
• Dizziness and malaise

Central Nervous System Effects (Rare)

• Somnolence (drowsiness) and insomnia
• Vertigo
• Confusion, agitation, and hallucinations — more commonly observed in severely ill elderly patients or those with renal or hepatic impairment; reversible upon discontinuation
• Depression
• Involuntary motor activity

Cardiovascular Effects

• Bradycardia — particularly with rapid IV injection; this is why IV Ranidin 150 mg must be infused slowly
• Tachycardia
• Atrioventricular (AV) block
• Ventricular premature contractions
• Vasculitis — rare

Gastrointestinal Effects

• Constipation, diarrhoea, and abdominal pain
• Nausea and vomiting
• Pancreatitis — rare
• Necrotizing enterocolitis — very rare, reported in very low-weight neonates

Hepatic Effects

• Elevated liver enzymes (ALT, AST, alkaline phosphatase) — typically transient; more likely with higher doses or prolonged IV therapy
• Hepatitis (with or without jaundice) — rare; usually reversible upon discontinuation

Hematological Effects (Rare)

• Thrombocytopenia (reduced platelet count)
• Leukopenia (reduced white blood cell count)
• Granulocytopenia and agranulocytosis
• Pancytopenia — rare
• Aplastic anaemia — rare but serious
• Acquired immune haemolytic anaemia

Skin and Hypersensitivity Reactions

• Skin rash and urticaria
• Alopecia (hair loss) — rare
• Erythema multiforme — rare
• Anaphylaxis and anaphylactoid reactions — rare; require immediate emergency treatment with epinephrine

Endocrine and Metabolic Effects

• Elevated serum prolactin — with IV doses; may cause breast tenderness or galactorrhoea rarely
• Gynecomastia — breast enlargement in males; reported with prolonged use, though less commonly than with cimetidine
• Vitamin B12 deficiency — prolonged treatment may lead to reduced vitamin B12 absorption through reduced gastric acid; risk is dose-related and higher in females and younger patients (under 30 years). Annual B12 monitoring is advisable with long-term Ranidin 150 mg therapy.
• Acute porphyria — rare precipitant in susceptible individuals

Injection Site Effects (Parenteral Use)

• Transient burning sensation or pain at the injection site (IM)
• Transient pruritus (itching) at the IV injection site

Laboratory Test Interference

• False-positive urine protein tests — Ranidin 150 mg may cause false-positive results when testing urine protein with the Multistix® reagent strip. Testing with sulfosalicylic acid is recommended as an alternative to confirm proteinuria in patients on Ranidin 150 mg.

Pregnancy

The US FDA Pregnancy Category for Ranidin 150 mg is Category B. Animal reproduction studies performed at doses substantially exceeding the human therapeutic dose have not demonstrated evidence of fetal malformations, teratogenicity, or impaired fertility. However, there are no adequate and well-controlled studies specifically in pregnant women. Because animal reproduction studies are not always predictive of human response, Ranidin 150 mg should be used during pregnancy only if clearly necessary and when the potential benefit to the mother justifies any theoretical risk to the fetus.

Ranidin 150 mg is considered one of the safer acid-suppressive agents during pregnancy when clinically indicated. It has been used by many pregnant women without evidence of harm, and the overall safety data in pregnancy are reassuring — but, as with all medications during pregnancy, use should be under physician supervision and limited to cases where treatment is genuinely required.

Lactation

Ranidin 150 mg is secreted into human breast milk. Ranidin 150 mg concentrations in breast milk can reach approximately two-thirds of corresponding plasma concentrations, suggesting meaningful infant exposure during breastfeeding. Caution should be exercised when Ranidin 150 mg is administered to nursing mothers. The decision to continue breastfeeding while taking Ranidin 150 mg should involve weighing the benefits of breastfeeding for the infant against the potential for drug exposure through breast milk. The physician should guide this decision on an individual basis.

Exclude Gastric Malignancy Before Treatment

Symptomatic response to Ranidin 150 mg therapy does not exclude the presence of gastric malignancy. Ranidin 150 mg relieves symptoms of gastric cancer as effectively as it relieves benign peptic ulcer symptoms, potentially masking the diagnosis and delaying appropriate treatment. When gastric ulcer is suspected, malignancy must be excluded before initiating Ranidin 150 mg therapy. Any patient with alarm symptoms (unexplained weight loss, dysphagia, persistent vomiting, hematemesis, iron-deficiency anaemia, or a palpable abdominal mass) should undergo endoscopy before treatment.

Renal Impairment — Dose Adjustment Required

Since Ranidin 150 mg is substantially excreted by the kidney, the risk of toxic reactions is significantly greater in patients with impaired renal function. Dose adjustment is mandatory in patients with creatinine clearance below 50 mL/min. Renal function should be assessed before initiating Ranidin 150 mg and monitored regularly during treatment, particularly in elderly patients who are more likely to have occult renal impairment.

Hepatic Impairment

Ranidin 150 mg is partially metabolized in the liver. Caution should be exercised in patients with hepatic dysfunction, as impaired hepatic metabolism may increase drug exposure. In severe hepatic impairment, dose adjustment may be necessary and liver function should be monitored. Rare cases of hepatitis with jaundice have been reported — discontinue Ranidin 150 mg if significant liver injury is suspected or confirmed.

Acute Porphyria

Rare reports suggest that Ranidin 150 mg may precipitate acute porphyric attacks in susceptible patients. Ranidin 150 mg should be avoided in patients with a history of acute porphyria.

Rapid Intravenous Injection — Cardiac Risk

Rapid or bolus intravenous injection of Ranidin 150 mg has been associated with bradycardia, hypotension, and cardiac arrhythmias. IV Ranidin 150 mg must always be administered slowly — direct IV injection should be given over at least 5 minutes (rate ≤4 mL/min). Continuous or intermittent IV infusions should be administered over 15–20 minutes. Cardiac monitoring is advisable in patients with pre-existing cardiac disease receiving parenteral Ranidin 150 mg.

CNS Effects in Elderly and Critically Ill Patients

Confusion, agitation, and hallucinations have been reported with Ranidin 150 mg — predominantly in severely ill elderly patients and in those with hepatic or renal impairment. These CNS effects are reversible upon discontinuation. Extra vigilance is required in this patient population.

Pneumonia Risk

Use of Ranidin 150 mg may increase the risk of developing pneumonia — potentially by raising gastric pH and allowing bacterial colonization of normally sterile gastric contents, with subsequent aspiration. Symptoms of pneumonia (chest pain, fever, shortness of breath, productive cough) should be reported to a physician promptly.

Vitamin B12 Monitoring with Long-Term Use

Prolonged Ranidin 150 mg treatment may lead to reduced vitamin B12 absorption through suppression of gastric acid (which is required to cleave B12 from food proteins). The risk is dose-related and greater in younger female patients. Annual vitamin B12 testing is advisable in patients on long-term Ranidin 150 mg therapy; supplementation may be required in those who develop B12 deficiency.

False-Positive Urine Protein Tests

Ranidin 150 mg may cause false-positive results for urine protein using the Multistix® reagent strip. When testing for proteinuria in patients taking Ranidin 150 mg, use the sulfosalicylic acid precipitation test as an alternative method to avoid false results.

NDMA Safety History — Important Regulatory Notice

In 2019–2020, the probable human carcinogen N-nitrosodimethylamine (NDMA) was detected in Ranidin 150 mg products from multiple manufacturers, leading to global market withdrawals including the US FDA's request in April 2020 and suspension across the EU and Australia. NDMA levels were found to increase in Ranidin 150 mg products over time and at elevated temperatures. In November 2025, the FDA approved a reformulated Ranidin 150 mg with improved manufacturing controls and stability testing demonstrating NDMA levels within internationally accepted limits. In countries where Ranidin 150 mg is currently available (including Bangladesh), patients and physicians should ensure products are sourced from manufacturers with adequate quality controls. If in doubt, discuss alternative acid-suppressing medications (famotidine, proton pump inhibitors) with your physician.

Ranidin 150 mg has a wide therapeutic margin. Clinical experience with intentional and accidental overdose suggests good tolerability even at very high doses. The following is known from overdose reports:

• Single oral doses as high as 18 g have been reported without serious adverse consequences
• Reported symptoms of Ranidin 150 mg overdose have been generally mild and consistent with the known adverse effect profile:
  • Nausea, vomiting, and abdominal pain
  • Headache and dizziness
  • Drowsiness and somnolence
  • Confusion and hallucinations (particularly in elderly patients)
  • Bradycardia and hypotension — particularly with IV overdose

Management of Overdose

• There is no specific antidote for Ranidin 150 mg overdose
• Management is symptomatic and supportive:
  • Remove unabsorbed drug — activated charcoal if the patient presents within 1 hour of ingestion and can protect their airway
  • Monitor vital signs, cardiac rhythm, and mental status
  • Provide supportive care for specific symptoms
  • Monitor renal and liver function
• Ranidin 150 mg is removable by hemodialysis — this may be considered in cases of severe overdose, particularly in patients with renal impairment where Ranidin 150 mg would not otherwise be cleared efficiently

In the event of suspected Ranidin 150 mg overdose, contact a poison control center or seek emergency medical care immediately.

• Store Ranidin 150 mg tablets, capsules, and syrup below 25°C–30°C, in a cool, dry place protected from direct light, heat, and moisture.
• Keep all formulations out of the reach of children.
• Do not use any formulation after the expiry date printed on the packaging or label.
• Store in original packaging — blister packs or tightly sealed bottles — to protect from humidity and light.
• Critical storage note: NDMA formation in Ranidin 150 mg has been shown to increase when products are stored at elevated temperatures. Do not store Ranidin 150 mg above 25°C. Avoid storage in hot environments such as car gloveboxes, near kitchen stoves, or in direct sunlight.
• Injection ampoules/vials: Store at room temperature, protected from light. Inspect solution for discoloration or particulate matter before use — discard if discolored (normally colorless to pale yellow). Single-use only; discard unused portions.
• Do not freeze any Ranidin 150 mg formulation.
• Ranidin 150 mg syrup — store at room temperature away from light. Use within the stated period after opening.

Elderly Patients

Ranidin 150 mg pharmacokinetics are altered in elderly patients due to age-related decline in renal function, reduced hepatic metabolic capacity, and increased volume of distribution. The plasma half-life is prolonged and total drug clearance is reduced. No routine dose adjustment is recommended based on age alone, but since elderly patients are more likely to have reduced renal function, renal function should be assessed before and during Ranidin 150 mg therapy, with dosing adjusted accordingly. Elderly patients are at higher risk of CNS adverse effects (confusion, hallucinations) and should be monitored accordingly.

Pediatric Patients (1 Month to 16 Years)

The safety and effectiveness of Ranidin 150 mg have been established in pediatric patients from 1 month to 16 years of age for the treatment of duodenal and gastric ulcers, GERD, and erosive esophagitis. Weight-based dosing (mg/kg) is required — see Dosage section for specific recommendations. The safety and effectiveness of Ranidin 150 mg in neonates under 1 month of age have not been established. Very rare cases of necrotizing enterocolitis have been reported in very low-weight neonates receiving IV Ranidin 150 mg, and its use in this group requires careful clinical judgement.

Patients with Renal Impairment

Since Ranidin 150 mg is primarily excreted by the kidneys (approximately 30–70% of a dose is excreted unchanged in the urine), dose adjustment is mandatory in patients with creatinine clearance below 50 mL/min (see Dosage section). In hemodialysis patients, Ranidin 150 mg is removed by dialysis — ideally schedule doses to coincide with the end of a dialysis session to restore therapeutic drug levels. Continuous IV infusion of Ranidin 150 mg has not been adequately evaluated in patients with severe renal impairment.

Patients with Hepatic Impairment

Ranidin 150 mg undergoes partial hepatic metabolism. In patients with severe hepatic dysfunction, reduced drug clearance may lead to accumulation and increased adverse effects — including CNS effects. Caution is advised, and dose adjustment may be necessary in severe hepatic impairment. Liver function should be monitored during Ranidin 150 mg therapy in patients with significant hepatic disease.