Isotrexin

Uses

Erythromycin tablet is highly effective in the treatment of a wide variety of clinical infections, such as

• Upper respiratory tract infections: Tonsillitis, peritonsillar abscess, pharyngitis, laryngitis, sinusitis, and secondary infections in cold and influenza.
• Lower respiratory tract infections: Tracheitis, acute and chronic bronchitis. Mycoplasma pneumoniae (lobar pneumonia, broncho pneumonia, primary atypical pneumoniae), bronchiectasis.
• Skin and soft tissue infections: Boils and carbuncles, paronychia, abscesses, pustular acne, impetigo, cellulitis, furuncolosis, erythrasma.
• Veneral infections: Non-specific urethritis, syphilis (if the patient is allergic to penicillin).
• Gastro-intestinal infections: Cholecystitis, Staphylococcal enterocolitis, infectious diarrhoea, & cholera.
• Ear and oral infections: 0titis media and otitis externa, gingivitis, dental abscesses.
• Prophylaxis: Pre-operative and post-operative, trauma, burns, rheumatic fever.
• Other infections: Diphtheria, whooping cough.

For topical treatment of acne, pimples & bacterial skin infections susceptible to Erythromycin

Isotretinoin is used for the treatment of severe recalcitrant nodular acne. Nodules are inflammatory lesions with a diameter of 5 mm or greater. The nodules may become suppurative or hemorrhagic. Because of significant adverse effects associated with its use, Isotretinoin should be reserved for patients with severe nodular acne who are unresponsive to conventional therapy, including systemic antibiotics. In addition, Isotretinoin is used only for those female patients who are not pregnant, because Isotretinoin can cause severe birth defects.

A single course of therapy for 15 to 20 weeks has been shown to result in complete and prolonged remission of disease in many patients. If a second course of therapy is needed, it should not be initiated until at least 8 weeks after completion of the first course, because experience has shown that patients may continue to improve while off Isotretinoin . The optimal interval before re-treatment has not been defined for patients who have not completed skeletal growth

Isotrexin is also used to associated treatment for these conditions: Acne, Acne Vulgaris, Acute Otitis Media caused by Haemophilus Influenzae, Acute pelvic inflammatory disease caused by Neisseria Gonorrheae Infection, Bacterial Infections, Chancroid, Chlamydia Trachomatis, Chlamydial ophthalmia neonatorum, Community Acquired Pneumonia (CAP), Diphtheria, Erythrasma, Gastroparesis, Granuloma Inguinale, Intestinal amebiasis caused by entamoeba histolytica, Legionella Pneumophila Infections, Listeria infection, Lower Respiratory Tract Infection (LRTI), Lymphogranuloma Venereum, Nongonococcal urethritis, Ophthalmia neonatorum (gonococcal), Pertussis, Postoperative Infections, Primary Syphilis, Respiratory Tract Infections (RTI), Staphylococcal Skin Infections, Syphilis, Upper Respiratory Tract Infection, Ureaplasma urethritis, Whooping Cough, Inflammatory papular lesions, Mild Acne vulgaris, Moderate Acne vulgaris, Predominant skin comedones, papules and pustules, Prophylaxis of Rheumatic fever, Pustular lesions, Skin and skin-structure infections, Skin and subcutaneous tissue bacterial infections caused by streptococcus pyogenes, Superficial ocular infectionsAcne Rosacea, Acne conglobata, Mycosis Fungoides (MF), Neuroblastomas, Sezary Syndrome, Refractory Acne vulgaris, Severe Recalcitrant nodular acne

How Isotrexin works

In order to replicate, bacteria require a specific process of protein synthesis, enabled by ribosomal proteins. Erythromycin acts by inhibition of protein synthesis by binding to the 23S ribosomal RNA molecule in the 50S subunit of ribosomes in susceptible bacterial organisms. It stops bacterial protein synthesis by inhibiting the transpeptidation/translocation step of protein synthesis and by inhibiting the assembly of the 50S ribosomal subunit. This results in the control of various bacterial infections. The strong affinity of macrolides, including erythromycin, for bacterial ribosomes, supports their broad‐spectrum antibacterial activities.

Isotretinoin produces its effects through altering progress through the cell cycle, cell differentiation, survival, and apoptosis. These actions reduce sebum production, preventing the blockage of pores, and growth of acne causing bacteria. Isotretinoin and 4-oxo-isotretinoin both significantly reduce the production of sebum. Isotretinoin has little to no affinity for retinol binding proteins (RBPs) and retinoic acid nuclear receptors (RARs). Tretinoin and 4-oxo-tretinion bind to the RAR-γ receptor, which is suspected to be part of the action of acne treatment by isotretinoin. Isotretinoin induces apoptosis in sebocytes, leading to a decrease in sebum production. Isotretinoin also reduces the formation of comedones by reducing hyperkeratinization through an unknown mechanism. Isotretinoin does not directly kill bacteria but it does reduce the size of sebum ducts and makes the microenvironment less hospitable to acne causing bacteria. It may also increase immune mechanisms and alter chemotaxis of monocytes to reduce inflammation.

There is preliminary evidence suggesting isotretinoin may interact with FoxO1, which may explain a substantial number of isotretinoin's unexplained actions.

Dosage

Isotrexin dosage

Adult and Child over 8 years: 250-500 mg every 6 hours or 0.5-1 gm every 12 hours. This may be increased up to 4 gm daily according to severity of infections.

Child of 2-8 years: 250 mg every 6 hours, doses doubled for severe infections.

Child up to 2 years: 125 mg every 6 hours.

Neonates: 30 to 45 mg/kg daily in 3 divided doses.

Elderly: Same as for adults.If administration on a twice daily schedule is desirable, one half of the total daily dose may be given every 12 hours, one hour before meal.

Amoebic dysentery:

• Adult: 250 - 500 mg four times daily for 10 - 14 days.
• Children: 30 - 50 mg/kg/day in divided doses for 10 - 14 days.

Pertussis: 30 - 50 mg/kg/day in divided doses for 5-14 days depending upon eradication of a positive culture.Streptococcal infections: In the treatment of group A beta haemolytic streptococcal infections, therapeutic dosage of Erythromycin should be administered for at least 10 days.

Acne: The usual dosage regimen of erythromycin in the treatment of acne is 500 mg twice daily for 3 months. Then the dose is to be reduced to 250 mg twice daily for another 3 months.

Early Syphilis: 500 mg 4 times daily for 14 days.Uncomplicated genital Chlamydia nongonococcal Urethritis: 500 mg twice daily for 14 days.

Prophylaxis: In continuous prophylaxis of streptococcal infections in person with a rheumatic heart disease, the dosage is 250 mg twice daily.

When Erythromycin is used prior to surgery to prevent endocarditis caused by alpha haemolytic streptococci, a recommended schedule:

• For children: 20 mg/Kg 1.5 - 2 hours pre-operatively and 10 mg/kg every 6 hours for 8 doses post-operatively.
• For adults:The dose is 1 g, 1.5 - 2 hours pre-operatively and 500 mg every 6 hours for 8 doses post-operatively.

Topical: Apply to the affected areas in the morning and evening. Before applying thoroughly wash with warm water and soap, rinse and pat dry all areas to be treated. Apply with applicator. Wash hands after use.

Oral-

• Adult: Initially, 0.5 mg/kg daily in single or 2 divided doses, increased to 1 mg/kg daily if necessary. Usual duration of treatment: 16-24 wk. May repeat treatment course after at least 8 wk if relapse after first course.
• Child: ≥12 yr Same as adult dose.

Topical:Apply Isotretinoin 0.05% gel cautiously over the affected area once or twice daily.Patients should be advised that 6-8 weeks of treatment may be required before a therapeuticeffect is observed. The safety and efficacy of Isotretinoin have not been established in children since acne vulgarisrarely present in this age group. There are no specific recommendations for use in the elderly.Acne vulgaris does not present in the elderly.

Direction for reconstitution of suspension: Shake the bottle to loosen powder. Add 60 ml (12 measuring spoonful) of boiled and cooled water to the dry powder of the bottle. For ease of preparation, add water to the bottle in two proportions. Shake well after each addition until all the powder 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 and unused portion should be discarded after 7 days.

Side Effects

Generally erythromycin is well tolerated and serious adverse effects are rare. Side-effects are gastrointestinal and are dose-related. They include nausea, vomiting, abdominal pain, diarrhea and anorexia. Mild allergic reactions, such as urticaria and skin rashes have occurred. Serious allergic reactions, including anaphylaxis may occur.

Erythema, skin exfoliation, stinging sensation, pruritus, irritation, tenderness, dry skin, hirsutism, photosensitivity, skin pigmentation, paronychia, nail dystrophy, pyogenic granuloma, increased sweating, corneal opacities, visual disturbances, headache, nausea and vomiting, arthralgia, myalgia, back pain, intracranial HTN, hyperostosis and calcinosis. Elevation of serum triglycerides, LFTs, ESR and blood glucose. Mood changes, psychotic symptoms, depression and suicidal behaviour.

Toxicity

LD50

The oral LD50 of erythromycin in rats is 9272 mg/kg.

Overdose information

Symptoms of overdose may include diarrhea, nausea, stomach cramps, and vomiting. Erythromycin should immediately be discontinued in cases of overdose. Rapid elimination of unabsorbed drug should be attempted. Supportive measures should be initiated. Erythromycin is not adequately removed by peritoneal dialysis or hemodialysis.

Patients experiencing an overdose may present with vomiting, facial flushing, cheilosis, abdominal pain, headache, dizziness, and ataxia. These symptoms may rapidly resolve. Generally no treatment is required for these overdoses.

The oral lowest dose causing toxic effect (TDLO) for children is 30mg/kg/21W, oral TDLO for men is 24mg/kg/4W, oral TDLO for women is 56mg/kg/8W. The intraperitoneal LD₅₀ for rats is 901mg/kg, oral LD₅₀ for mice is 3389mg/kg, oral LD₅₀ for rats is >4000mg/kg.

Isotretinoin is associated with major congenital malformations, spontaneous abortion, and premature birth. It is unknown if isotretinoin is expressed in breast milk but due to the associated hazards a decision should be made to either stop nursing or stop taking isotretinoin.

In animal studies, isotretinoin was associated with an increased risk of pheochromocytoma and adrenal medullary hyperplasia at doses above the recommended clinical dose. Isotretinoin was negative for the Ames test of mutagenicity once and weakly positive a second time. It has not been shown to be clastogenic. A study in dogs noted testicular atrophy after doses of 10-30 times the recommended clinical dose for 30 weeks. In trials with men there were no effects seen on sperm count, motility, morphology, ejaculate volume, and seminal plasma fructose.

Precaution

Lotion/Cream: For external use only. Keep away from eyes, nose, mouth and other mucous membrane.

Use of antibiotics (especially prolonged or repeated therapy) may result in bacterial or fungal overgrowth of non-susceptible organisms. Such overgrowth may lead to a secondary infection. Take appropriate measures if superinfections occur.

Tablet: Since Erythromycin is metabolized principally by the liver, caution should be exercised when erythromycin is administered to patients with impaired hepatic function. There have been reports of hepatic dysfunction with or without jaundice occurring in patients taking oral Erythromycin.

Women of childbearing potential; anorexia nervosa. History of photoallergy, psychiatric disorder (e.g. depression); pre-existing or predisposition to hypertriglyceridaemia (e.g. DM, obesity or increased alcohol intake). Genetic predisposition for age-related osteoporosis, history of childhood osteoporosis, osteomalacia or other bone metabolism disorders. Not intended for the treatment of prepubertal acne. Severe renal impairment.

Interaction

Theophylline: The use of Erythromycin in patients who are receiving concomitant high doses of theophylline may be associated with an increase in serum theophylline and potential theophylline toxicity. If symptoms of toxicity develop, the dose of theophylline should be reduced.

Digoxin: Concomitant administration of Erythromycin and Digoxin has been reported to result in elevated digoxin serum levels.

Clindamycin interacts with Erythromycin

Additive adverse effects with vit A or its derivatives. Decreased efficacy of microdosed progesterone (use 2 forms of contraception).Increased risk of local irritation with topical keratolytic or exfoliative anti-acne agents. Oxidising agents (e.g. benzoyl peroxide) may reduce the efficacy of topical isotretinoin.

Volume of Distribution

Erythromycin is found in most body fluids and accumulates in leucocytes and inflammatory liquid. Spinal fluid concentrations of erythromycin are low, however, the diffusion of erythromycin through the blood-brain barrier increases in meningitis, likely due to the presence of inflamed tissues which are easily penetrated. Erythromycin crosses the placenta.

The volume of distribution in humans is unknown because there is no intravenous preparation. In a study of pediatric patients with neuroblastoma the volume of distribution was found to be 85L. The volume of distribution was also found to be 2432mL/kg in guinea pigs and 1716mL/kg in obese rats.

Elimination Route

Orally administered erythromycin is readily absorbed. Food intake does not appear to exert effects on serum concentrations of erythromycin. Some interindividual variation exists in terms of erythromycin absorption, which may impact absorption to varying degrees. The Cmax of erythromycin is 1.8 mcg/L and the Tmax is 1.2 hours. The serum AUC of erythromycin after the administration of a 500mg oral dose was 7.3±3.9 mg.h/l in one pharmacokinetic study. Erythromycin is well known for a bioavailability that is variable (18-45%) after oral administration and its susceptibility to broken down under acidic conditions.

Patients reach a maximum concentration of 74-511ng/mL after 1-4 hours following a 100mg oral dose. Isotretinoin is better absorbed with a high fat meal and bioavailability may change from one brand to another.

Following a 40mg oral dose, fasted subjects reached a maximum concentration of 314ng/mL in 2.9 hours with an area under the curve of 4055ng/mL*hr. Subjects given a high fat meal and a 40mg oral doses reached a maximum concentration of 395ng/mL in 6.4 hours with an area under the curve of 6095ng/mL*mL.

Half Life

The elimination half-life of oral erythromycin was 3.5 hours according to one study and ranged between 2.4-3.1 hours in another study. Repetitive dosing of erythromycin leads to increased elimination half-life.

The half life ranges from 7-39 hours with a mean elimination half life of 20 hours. The half life of 4-oxo-13-cis-retinoic acid ranges from 17-50 hours with a mean elimination half life of 25 hours.

Clearance

The clearance of erythromycin in healthy subjects was 0.53 ± 0.13 l/h/kg after a 125mg intravenous dose. In a clinical study of healthy patients and patients with liver cirrhosis, clearance of erythromycin was significantly reduced in those with severe liver cirrhosis. The clearance in cirrhotic patients was 42.2 ± 10.1 l h–1 versus 113.2 ± 44.2 l h-1 in healthy patients.

The clearance of isotretinoin is 15.9L/h in pediatric patients with neuroblastoma. Clearance is also 21.3mL/min/kg in guinea pigs and 7.2mL/min/kg in obese rats.

Elimination Route

In patients with normal liver function, erythromycin concentrates in the liver and is then excreted in the bile.Under 5% of the orally administered dose of erythromycin is found excreted in the urine. A high percentage of absorbed erythromycin is not accounted for, but is likely metabolized.

Isotretinoin and its metabolites are conjugated and excreted in the urine and feces in similar amounts. 53-74% of an oral dose is eliminated as unchanged isotretinoin in the feces.

Pregnancy & Breastfeeding use

Safety for use during pregnancy has not been established. Use only when the potential benefits outweigh potential hazards to the fetus.

Erythromycin is excreted in breast milk. Exercise caution when administering to a nursing mother.

Category X: Studies in animals or human beings have demonstrated foetal abnormalities or there is evidence of foetal risk based on human experience or both, and the risk of the use of the drug in pregnant women clearly outweighs any possible benefit. The drug is contraindicated in women who are or may become pregnant.

Contraindication

Erythomycin is contraindicated in patients with a known hypersensitivity to this drug.

Hypervitaminosis A, hyperlipidaemia. Hepatic impairment. Pregnancy and lactation. Concomitant admin of tetracycylines.

Special Warning

Safety and effectiveness in children less than 12 years have not been established.

Renal Impairment: Oral: Severe: Reduce initial dose (e.g. 10 mg daily), then gradually increase to 1 mg/kg as necessary.

Hepatic Impairment: Oral: Contraindicated.

Acute Overdose

In case of overdosage, Erythromycin should be discontinued. Overdosage should be handled with the prompt elimination of unabsorbed drug and all other appropriate measures should be instituted. Erythromycin is not removed by peritoneal dialysis or haemodialysis.

Storage Condition

Keep at room temperature and away from light.

Store between 20-25° C. Protect from light.

Innovators Monograph

You find simplified version here Isotrexin