Histac

Symptomaticreliefofheartburn, indigestion,acidindigestionand hyperacidity.

Route of Administration

Oral

Dosage

Adults (Including the elderly) and children 16 years of age and older:

Swallow one Histac 75 Relief tablet whole, with a drink of water, as soon as you have symptoms. If symptoms persist for more than one hour or return, take another tablet. Do not take more than two tablets in 24 hours.

Do not take the tablets for more than 6 days without the advice of a pharmacist or doctor.

Children under 16 years

Not recommended for children under 16 years of age.

Ranitidine is contraindicated for people known to be hypersensitive to the drug or any of the ingredients of Histac 75 Relief tablets.

Treatment with a histamine H₂-antagonist such as Histac 75 Relief may mask symptoms associated with carcinoma of the stomach and may therefore delay diagnosis of the condition.

Ranitidine is excreted via the kidney and so plasma levels of the drug are increased in patients with renal impairment (creatinine clearance less than 50 ml/min). Histac 75 Relief is not suitable for these patients without medical supervision.

People taking non-steroidal anti-inflammatory drugs, especially those with a history of peptic ulcer and the elderly, should not self-medicate with Histac 75 Relief but seek their doctor's advice before use.

People with a history of porphyria should avoid use of the product.

Consumers will be advised not to purchase a second pack of tablets without the advice of a pharmacist of doctor.

The product is not indicated in the following people without seeking their doctor's advice:

- Patients with renal impairment (creatinine clearance less than 50ml/min) and/or hepatic impairment.

- Patients under regular medical supervision for other reasons.

- Patients taking medications either physician prescribed or self-prescribed.

- Those with difficulty swallowing, persistent stomach pain or unintended weight loss in association with symptoms of indigestion.

- Those who are middle-aged or elderly with new or recently changed symptoms of indigestion.

In patients such as the elderly, persons with chronic lung disease, diabetes or the immunocompromised, there may be an increased risk of developing community acquired pneumonia.

A large epidemiological study showed an increased risk of developing community acquired pneumonia in current users of ranitidine alone versus those who had stopped treatment, with an observed adjusted relative risk increase of 1,82 (95% CI 1,26-2,64).

No known effect

The following convention has been utilised for the >

Blood & Lymphatic System Disorders

Very Rare:

Blood count changes (leucopenia, thrombocytopenia). These are usually reversible. Agranulocytosis or pancytopenia, sometimes with marrow hypoplasia or marrow aplasia.

Immune System Disorders

Rare:

Hypersensitivity reactions (urticaria, angioneurotic oedema, fever, bronchospasm, hypotension and chest pain).

Very Rare:

Anaphylactic shock

These events have been reported after a single dose.

Psychiatric Disorders

Very Rare:

Reversible mental confusion, depression and hallucinations.

These have been reported predominantly in severely ill and elderly patients.

Nervous System Disorders

Very Rare:

Headache (sometimes severe),dizziness and reversible involuntary movement disorders.

Eye Disorders

Very Rare:

Reversible blurred vision.

There have been reports of blurred vision, which is suggestive of a change in accommodation.

Cardiac Disorders

Very Rare:

As with other H₂ receptor antagonists bradycardia and A-V Block.

Vascular Disorders

Very Rare:

Vasculitis.

Gastrointestinal Disorders

Very Rare:

Acute pancreatitis. Diarrhoea.

Uncommon:

Abdominal pain, constipation, nausea. (these symptoms mostly improved during continued treatment).

Hepatobiliary Disorders

Rare:

Transient and reversible changes in liver function tests.

Very Rare

Hepatitis (hepatocellular, hepatocanalicular or mixed) with or without jaundice, these were usually reversible.

Skin and Subcutaneous Tissue Disorders

Rare:

Skin Rash.

Very Rare:

Erythema multiforme, alopecia.

Musculoskeletal and Connective Tissue Disorders

Very Rare:

Musculoskeletal symptoms such as arthralgia and myalgia.

Renal and Urinary Disorders

Very rare:

Acute interstitial nephritis.

Rare:

Elevation of plasma creatinine (usually slight; normalised during continued treatment)

Reproductive System and Breast Disorders

Very Rare:

Reversible impotence. Breast symptoms and breast conditions (such as gynaecomastia and galactorrhea).

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme at: www.mhra.gov.uk/yellowcard.

Symptoms and Signs

Ranitidine is very specific in action and no particular problems are expected following overdose with the drug. Up to 6g per day has been administered without untoward effect.

Treatment

Symptomatic and supportive therapy should be given as appropriate. If need be, the drug may be removed from the plasma by haemodialysis.

ATC Code

Pharmacotherapeutic group: H2-receptor antagonist, ATC code: A02BA02

Pharmacotherapeutic group

H2-receptor antagonists, ATC code: A02BA02

Mechanism of Action

Ranitidine is a specific, rapidly acting histamine H2-antagonist. It inhibits basal and stimulated secretion of gastric acid, reducing both the volume and the acid and pepsin content of the secretion

Pharmacodynamic Effects

Ranitidine has a long duration of action and a single 75 mg dose effectively suppresses gastric acid secretion for at least 12 hours.

Absorption

Following oral administration of 150 mg ranitidine, maximum plasma concentrations (300 to 550 ng/mL) occurred after 1-3 hours. Two distinct peaks or a plateau in the absorption phase result from reabsorption of drug excreted into the intestine. The absolute bioavailability of ranitidine is 50-60%, and plasma concentrations increase proportionally with increasing dose up to 300 mg.

Absorption is not significantly impaired by food or antacids.

Distribution

Ranitidine is not extensively bound to plasma proteins (15%), but exhibits a large volume of distribution ranging from 96 to 142 L.

Metabolism

Ranitidine is not extensively metabolised. The fraction of the dose recovered as metabolites includes 6% of the dose in urine as the N-Oxide, 2% as the S-Oxide, 2% as desmethyl ranitidine and 1-2% as the furoic acid analogue.

Elimination

Plasma concentrations decline bi-exponentially, with a terminal half-life of 2-3 hours. The major route of elimination is renal. After IV administration of 150 mg ³H- ranitidine, 98% of the dose was recovered, including 5% in the faeces and 93% in the urine, of which 70% was unchanged parent drug. After oral administration of 150 mg ³H-ranitidine, 96% of the dose was recovered, 26% in the faeces and 70% in urine of which 35% was unchanged parent drug. Less than 3% of the dose is excreted in bile. Renal clearance is approximately 500mL/min, which exceeds glomerular filtration indicating net renal tubular secretion.

Special Patient Populations

- Patients over 50 years of age

In patients over 50 years of age, half-life is prolonged (3-4 h) and clearance is reduced, consistent with the age-related decline of renal function. However, systemic exposure and accumulation are 50% higher. This difference exceeds the effect of declining renal function, and indicates increased bioavailability in older patients.

Extensive studies have been carried out in animals. The pharmacology of ranitidine hydrochloride shows it to be a surmountable H2 receptor antagonist which produces an inhibition of gastro acid secretion. Extensive toxicological investigators have been conducted which predicted a very safe profile for clinical use. This safety has been confirmed by extensive use in patients for many years.

None known

No special instructions