Description and Composition of Mephamycin
Mephamycin is an antibiotic used in the treatment of suspectible bacterial infections. It contains a macrolide antibiotic called Erythromycin Stearate as its active pharmaceutical ingredient. In addition, it contains other inactive ingredients called excipients in sufficient quantities. Mephamycin comes in different dosage forms which include capsule, tablet, long-acting capsule, long-acting tablet, chewable tablet, suspension, and pediatric drop forms for oral use, topical solution and gel forms and as an ophthalmic ointment. It comes in different dosage strengths.
Mechanism of Action, Pharmacokinetics and Pharmacodynamics of Mephamycin
Mephamycin acts by inhibition of protein synthesis by binding 50’S ribosomal subunits of susceptible organisms.
It does not affect nucleic acid synthesis. Antagonism has been demonstrated in vitro between erythromycin and clindamycin, lincomycin, and Chloramphenicol. Many strains of Haemophilus influenzae are resistant to erythromycin alone but are susceptible to erythromycin and sulfonamides used concomitantly. Staphylococci resistant to erythromycin may emerge during a course of erythromycin therapy.
Erythromycin is largely bound to plasma proteins. After absorption, erythromycin diffuses readily into most body fluids. In the absence of meningeal inflammation, low concentrations are normally achieved in the spinal fluid but the passage of the drug across the blood-brain barrier increases in meningitis. Erythromycin crosses the placental barrier, but fetal plasma levels are low. The drug is excreted in human milk
Indications and Uses of Mephamycin
- Mephamycin has been used in the treatment of a wide variety of infections caused by susceptible organisms.
- It is used to treat bronchitis, severe Campylobacter enteritis, Chancroid, diptheria legionnaire’s disease and other legionella infections, neonatal conjuntivitis, pertussis, pneumonia (mycoplasmal and other atypical pneumonias as well as streptococcal), sinusitis.
- Erythromycin is used as an alternative to penicillin in penicillin-allergic patients with various conditions including anthrax, the prophylaxis of endocarditis, leptospirosis, otitis media (usually with a Sulfonamide such as Sulphafurazole), pharyngitis prevention of rheumatic fever, Staphylococcal and Streptococcal skin infections.
- It has also been used in the treatment of penicillin-allergic patients with syphilis. It is also used as an alternative to tetracyclines in patients with Chlamydial infections (such as epididymitis, lymphogranuloma venereum, non gonococcal urethritis, Chlamydial pneumonia, psittacosis, Q fever and trachoma), in pelvic inflammatory disease (PID) and in tularemia.
- Oral erythromycin may be employed in severe acne.
Contraindications of Mephamycin
Mephamycin is contraindicated or shouldn’t be used in patients with known hypersensitivity to this antibiotic.
Mephamycin is principally excreted by the liver. Caution Should be exercised in administering the antibiotic to patients with impaired hepatic function. There have been reports of hepatic dysfunction, with or without jaundice, occurring in patients receiving oral erythromycin products, it has been suggested that erythromycin should be used with care in patients with a history of arrhythmia.
Side Effects of Mephamycin
Side effects associated with Mephamycin use include
- Abdominal discomfort,
- sore mouth or tongue and
- allergic reactions: Such as rashes, itching, swelling and dizziness.
Drug Interactions with Mephamycin
The concomitant administration of theophylline with Mephamycin causes potential theophylline toxicity. In such cases the dose of theophylline should be reduced while the patient is receiving concomitant erythromycin therapy.
Erythromycin administration in children receiving carbamazepine has been reported to cause increased blood levels of carbamazepine with subsequent development of signs of carbamazepine toxicity (ataxia, dizziness, vomiting)
Erythromycin may decrease the clearance of warfarin and thus potentiate the hypoprothrombinemic effect of warfarin.
Erythromycin has been reported to decrease the clearance of triazolam and thus may increase the pharmacologic effect of triazolam.
Erythromycin has been reported to decrease the clearance of cyclosporine causing elevated cyclosporine levels and associated increased serum creatinine. Renal function as well as serum concentration of cyclosporine should be closely monitored when both drugs are administered concomitantly.
The interaction between erythromycin and ergotamine has been reported to increase the vasospasm associated with ergotamine,
Antagonism in antibacterial activity has been demonstrated between clindamycin and erythromycin in vivo.
Dosage and Method of Administration of Mephamycin
General dosing recommendation
Adults dose: 250mg every six hours
500mg every twelve hours
Children: 30-50mg/kg/day in equal divided dose.
Adult Dosing Recommendations
500 mg PO q6hr for 10-14 days
1-4 g/day PO in divided doses for 21 days
Urethritis caused by C trachomatis or U urealyticum
500 mg PO q6hr for 7 days; alternatively 333 mg PO q8hr for 7 days
30-40 g PO in divided doses for 10-15 days
Children Dosing Recommendations
General Dosing Recommendations
Mild-to-moderate infections: 30-50 mg/kg/day PO divided q6-8hr
30-50 mg/kg/day PO in divided doses for 10-14 days
Pneumonia of Infancy
50 mg/kg/day PO divided q6hr for at least 3 weeks
Dosing terms: PO is per Oral , q6hr is every 6 hours, q8hr is 8 hourly,
Over dosage of Mephamycin
Allergic reactions associated with acute overdose of Mephamycin should be handled in the usual manner that is by the administration of adrenaline, corticosteroids and antihistamine as indicated and the prompt elimination of unabsorbed drug in addition to all needed supportive measures.
How to Store Mephamycin
Store in a cool, dry place at a temperature not exceeding 25°C. Protect from light. Keep all medicine away from reach of children.
References and More Reading