Melysin

Melysin is indicated for the treatment of infections due to mecillinam sensitive organisms , including:

- urinary tract infections

- salmonellosis

Preliminary experience in a small number of patients suggests that Melysin tablets may be a useful alternative antibiotic in the treatment of acute typhoid fever and in some carriers of salmonellae when antibiotic treatment is considered essential.

Consideration should be given to official guidance on the appropriate use of antibacterial agents.

Posology

Adults and children weighing more than 40 kg:

Urinary tract infections:

- Acute uncomplicated cystitis: 72 hour course of 2 tablets immediately followed by 1 tablet 3 times daily to a total of 10 tablets.

- Chronic or recurrent bacteriuria: 2 tablets three to four times daily.

Salmonellosis:

- Enteric fever: 1.2-2.4 g daily for 14 days.

- Salmonella carriers: 1.2-2.4 g daily for 2-4 weeks.

Children weighing less than 40 kg:

- Urinary tract infections: 20-40 mg/kg body weight, daily, in 3 to 4 divided doses.

- Salmonellosis: 30-60 mg/kg body weight, daily, in 3 to 4 divided doses.

Dosage in the elderly:

Renal excretion of mecillinam is delayed in the elderly, but significant accumulation of the drug is not likely at the recommended adult dosage of Melysin tablets.

Method of administration

Route of administration is oral. The tablets must be taken with at least half a glass of fluid, and preferably taken with or immediately after a meal.

Hypersensitivity to penicillins and/or cephalosporins. Any conditions resulting in impaired transit through the oesophagus.

Genetic metabolism anomalies known to be leading to severe carnitine deficiency, such as carnitine transporter defect, methylmalonic aciduria or propionic acidaemia.

During long term use, it is advisable to carry out routine liver and kidney function tests.

Pseudomembranous colitis caused by Clostridium difficile may occur. If diarrhoea occurs after use, the possibility of pseudomembranous colitis should be considered, and appropriate actions should be taken.

Melysin tablets should be used with caution in patients with porphyria since pivmecillinam has been associated with acute attacks of porphyria.

As with other antibiotics which are excreted mainly by the kidneys, raised blood levels of mecillinam may occur if repeated doses are given to patients with impaired renal function.

Melysin tablets should be used with caution for long-term or frequently-repeated treatment, due to the possibility of carnitine depletion. Symptoms of carnitine depletion include muscle aches, fatigue, and confusion.

Concurrent treatment with valproic acid, valproate or other medication liberating pivalic acid should be avoided due to increased risk of carnitine depletion.

The tablets must be taken with at least half a glass of fluid due to risk of oesophageal ulceration.

Melysin has no or negligible influence on the ability to drive or use machines.

The estimation of the frequency of undesirable effects is based on an analysis of pooled data from clinical studies and spontaneous reporting.

The most frequently reported undesirable effects are nausea and diarrhoea.

Anaphylactic reactions and fatal pseudomembranous colitis have been reported.

Undesirable effects are listed by MedDRA SOC and the individual undesirable effects are listed starting with the most frequently reported. Within each frequency grouping, adverse reactions are presented in the order of decreasing seriousness.

Very common > 1/10

Common > 1/100 and < 1/10

Uncommon > 1/1,000 and < 1/100

Rare > 1/10,000 and < 1/1,000

Very Rare < 1/10,000

*Various types of rash reactions such as erythematous, macular or maculo-papular have been reported

Class adverse reactions of beta-lactam antibiotics:

Slight reversible increase in ASAT, ALAT, alkaline phosphatase, and bilirubin

Neutropenia

Eosinophilia

Paediatric population

Frequency, type and severity of adverse reactions in children are expected to be the same as in adults, based on limited data.

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.

There has been no experience of overdosage with Melysin. However, excessive doses of Melysin are likely to induce nausea, vomiting, abdominal pain and diarrhoea. Treatment should be restricted to symptomatic and supportive measures.

Pharmacotherapeutic group: antibacterial products for systemic use, penicillins with extended spectrum, ATC code: J01CA08

Melysin is an orally active antibiotic. Chemically it is the pivaloyloxymethylester of the amidinopenicillanic acid, mecillinam. On oral administration it is well absorbed and subsequently hydrolysed in the body to mecillinam, the active antibacterial agent, by non-specific esterases present in blood, gastro-intestinal mucosa and other tissues.

Melysin is highly active against most enterobacteriaceae, including E. coli, Klebsiella, Proteus, Enterobacter, Serratia, Salmonella, Shigella and Yersina.

Melysin is less active against gram positive bacteria and organisms such as Pseudomonas aeruginosa and Streptococcus faecalis are practically resistant to mecillinam.

Whilst Melysin, like the penicillins and cephalosporins, interferes with the biosynthesis of the bacterial cell wall, the target of the inhibition is different. This different mode of action is probably responsible for the synergistic action which has been found, both in vitro and in vivo, between Melysin and various penicillins and cephalosporins.

Peak serum levels of mecillinam averaging 5 microgram/ml are reached after 1 hour following a dose of 10 mg/kg body weight in children and 400 mg in adults.

The serum half-life is 1.2 hours. The protein binding amounts to 5-10%. Approximately 50% of the administered dose is excreted as mecillinam in the urine within the first six hours. Mecillinam is partly excreted with bile, giving rise to biliary concentrations about 3 times the serum levels.

Concurrent administration of probenecid delays the renal excretion of mecillinam, producing more sustained serum levels. The absorption of Melysin is practically unaffected by taking the tablets with food.

There are no pre-clinical data of relevance to the prescriber which are additional to that already included in other sections of the SPC.

Not applicable.

No special requirements for disposal.