Rithinex

Uses

• LRTIs for example, acute and chronic bronchitis and pneumonia.
• URTIs for example, sinusitis and pharyngitis.
• Community-acquired pneumonia, atypical pneumonia
• Skin and soft tissue infection
• Adjunct in the treatment of duodenal ulcers to eradicate of H. pylori

Rithinex is also used to associated treatment for these conditions: Acute Bacterial Exacerbation of Chronic Bronchitis (ABECB), Acute maxillary sinusitis, Bacterial Infections, Bartonellosis, Community Acquired Pneumonia (CAP), Duodenal ulcer caused by helicobacter pylori, Infective Endocarditis, Lyme Disease, Mycobacterial Infections, Otitis Media (OM), Pertussis, Streptococcal Pharyngitis, Streptococcal tonsillitis, Uncomplicated skin and subcutaneous tissue bacterial infections

How Rithinex works

Rithinex is first metabolized to 14-OH clarithromycin, which is active and works synergistically with its parent compound. Like other macrolides, it then penetrates bacteria cell wall and reversibly binds to domain V of the 23S ribosomal RNA of the 50S subunit of the bacterial ribosome, blocking translocation of aminoacyl transfer-RNA and polypeptide synthesis. Rithinex also inhibits the hepatic microsomal CYP3A4 isoenzyme and P-glycoprotein, an energy-dependent drug efflux pump.

Dosage

Rithinex dosage

Rithinex may be given with or without meals.

Adults (12 years or above):

250 mg twice daily for 7 days. Dose may be increased to 500 mg twice daily for up to 14 days in pneumonia or severe infections.

Combination therapy for H. pylori infection:

Rithinex 500 mg (two 250 mg tablets or one 500 mg tablet) twice daily in combination with Amoxicillin 1000 mg twice daily and Omeprazole 20 mg twice daily should be continued for 10 days.

Children:

The usual recommended daily dosage is 15 mg/kg in 2 divided doses for 10 days.

Approximate Calculation of dose:

1. For 9kg body weight 2.5ml 12 hourly for 10 days

2. For 17kg body weight 5ml 12 hourly for 10 days

3. For 25kg body weight 7.5ml 12 hourly for 10 days

4. For 33kg body weight 10ml 12 hourly for 10 days

Direction for reconstitution of suspension:

Shake the bottle to loosen granules. Add 35 ml of boiled and cooled water with the help of the supplied cup, to the dry granules of the bottle. For ease of preparation, add water to the bottle in two proportions. Shake well after each addition until all the granules is in suspension.

Note: Shake the suspension well before each use. Keep the bottle tightly closed. The reconstituted suspension should be stored in a cool and dry place, preferably in refrigerator.

This may be given with or without meals.

The usual duration of treatment is 6 to 14 days.

Children older than 12 years: As for adults.

Eradication of H. pylori in patients with duodenal ulcers: Adults: The usual duration of treatment is 6 to 14 days.

45 ml of water is to be added to the granules in the bottle and shaken to yield 70 ml of reconstituted suspension. The concentration of clarithromycin in the reconstituted suspension is 125 mg per 5 ml.

Side Effects

The most frequently reported events in adults taking Rithinex were diarrhoea (3%), nausea (3%), abnormal taste (3%), dyspepsia (2%), abdominal pain/discomfort (2%), headache (2%) and oral monilia.

Toxicity

Symptoms of toxicity include diarrhea, nausea, abnormal taste, dyspepsia, and abdominal discomfort. Transient hearing loss with high doses has been observed. Pseudomembraneous colitis has been reported with clarithromycin use. Allergic reactions ranging from urticaria and mild skin eruptions to rare cases of anaphylaxis and Stevens-Johnson syndrome have also occurred. Rare cases of severe hepatic dysfunctions also have been reported. Hepatic failure is usually reversible, but fatalities have been reported. Rithinex may also cause tooth decolouration which may be removed by dental cleaning. Fetal abnormalities, such as cardiovascular defects, cleft palate and fetal growth retardation, have been observed in animals. Rithinex may cause QT prolongation.

Precaution

Caution should be taken in administering this antibiotic to patients with impaired hepatic and renal function. Prolonged or repeated use of Rithinex may result in an overgrowth of nonsusceptible bacteria or fungi. If superinfection occurs, Rithinex should be discontinued.

Pharmaceutical precaution

Rithinex tablet should be stored in a cool and dry place and away from sunlight.

Interaction

Concomitant use of Rithinex who are receiving Theophylline may be associated with an increase in serum Theophylline concentrations. Rithinex may alter the metabolism of Terfenadine. The effects of digoxin may be potentiated with concomitant administration of Rithinex. Rithinex resulted in decrease in serum levels of Rifabutin, followed by an increased risk of uveitis.

Food Interaction

• Take with food. Food increases absorption.

[Minor] Grapefruit juice may delay the gastrointestinal absorption of clarithromycin but does not appear to affect the overall extent of absorption or inhibit the metabolism of clarithromycin.

The mechanism of interaction is unknown but may be related to competition for intestinal CYP450 3A4 and

In an open-label, randomized, crossover study consisting of 12 healthy subjects, coadministration with grapefruit juice increased the time to reach peak plasma concentration (Tmax) of both clarithromycin and 14-hydroxyclarithromycin (the active metabolite) by 80% and 104%, respectively, compared to water.

Other pharmacokinetic parameters were not significantly altered.

This interaction is unlikely to be of clinical significance.

Rithinex Drug Interaction

Moderate: albuterol / ipratropium, albuterol / ipratropiumMinor: amoxicillin / clavulanate, amoxicillin / clavulanate, esomeprazole, esomeprazoleUnknown: diphenhydramine, diphenhydramine, acetaminophen, acetaminophen, acetaminophen, acetaminophen, cyanocobalamin, cyanocobalamin, ascorbic acid, ascorbic acid, cholecalciferol, cholecalciferol, cetirizine, cetirizine

Rithinex Disease Interaction

Major: colitis, QT prolongationModerate: renal dysfunction, myasthenia gravis

Elimination Route

Rithinex is well-absorbed, acid stable and may be taken with food.

Half Life

3-4 hours

Elimination Route

After a 250 mg tablet every 12 hours, approximately 20% of the dose is excreted in the urine as clarithromycin, while after a 500 mg tablet every 12 hours, the urinary excretion of clarithromycin is somewhat greater, approximately 30%.

Pregnancy & Breastfeeding use

Rithinex is not recommended for pregnant women. Breast milk from mothers receiving Rithinex should not be given to infants until treatment is completed. Rithinex may be used in neonates and children in appropriate doses.

Contraindication

Hypersensitive to Rithinex, Erythromycin or any of the macrolide antibiotics. Patients receiving terfenadine who have pre-existing cardiac abnormalities or electrolyte disturbances.

Special Warning

Rithinex may be used in neonates and children in appropriate doses.

Acute Overdose

Signs & Symptoms : Ingestion of large amounts of Rithinex can be expected to produce gastrointestinal symptoms. Symptoms of overdose may largely correspond to the profile of side effects.

Management: There is no specific antidote on overdose. Serum levels of Rithinex can not be reduced by haemodialysis or peritoneal dialysis.

Storage Condition

Store in a cool and dry place, protected from light.

Innovators Monograph

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