Ovex/Ovex Family Pack/Boots Threadworm Tablets/ Threadworm Tablets 2 Years Plus

Mebendazole 100 mg.

Tablet.

For the treatment of gastrointestinal infestations of Enterobius vermicularis (threadworm).

There is no evidence that Ovex is effective in the treatment of cysticercosis.

Ovex is for oral administration.

Adults and children over 2 years:

Take one tablet.

Tablets may be chewed or swallowed whole. Crush the tablet before giving it to a young child. Always supervise a child while they are taking this medicine. Care should be taken to avoid re-infection and it is strongly recommended that all members of the family are treated at the same time.

It is highly recommended that a second tablet is taken after two weeks, if re-infection is suspected.

Ovex is contra-indicated in pregnancy and in patients who have shown hypersensitivity to the product or any components.

Ovex is not recommended in the treatment of children aged under 2 years.

If symptoms do not disappear within a few days, consult your doctor.

A case-control study of a single outbreak of Stevens-Johnson syndrome /toxic epidermal necrolysis (SJS/TEN) suggested a possible association with the concomitant use of metronidazole with mebendazole. Although there are no additional data on this potential interaction, concomitant use of mebendazole and metronidazole should be avoided.

Concomitant treatment with cimetidine may inhibit the metabolism of mebendazole in the liver, resulting in increased plasma concentrations of the drug.

Concomitant use of mebendazole and metronidazole should be avoided (see section 4.4).

Use in pregnancy

Since Ovex is contra-indicated in pregnancy patients who think they are or may be pregnant should not take this preparation.

Use in lactation

As it is not known whether mebendazole is excreted in human milk, it is not advisable to breast feed following administration of Ovex.

None known.

Throughout this section adverse reactions are reported. Adverse reactions are adverse events that were considered to be reasonably associated with the use of mebendazole based on the comprehensive assessment of the available adverse event information. A causal relationship with mebendazole cannot be reliably established in individual cases. Further, because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.

At the recommended dose, Ovex is generally well tolerated. However, patients with high parasitic burdens when treated with Ovex have manifested diarrhoea and abdominal pain.

The safety of mebendazole was evaluated in 6276 subjects who participated in 39 clinical trials for the treatment of single or mixed parasitic infestations of the gastrointestinal tract. In these 39 clinical trials, no adverse drug reactions (ADRs) occurred in 1% of mebendazole-treated subjects.

ADRs identified from clinical trials and post-marketing experience with mebendazole are included in Table 1. The displayed frequency categories use the following convention:

Very common ( 1/10); Common ( 1/100 and < 1/10); Uncommon ( 1/1000 and < 1/100); Rare ( 1/10,000 and < 1/1000); Very rare (< 1/10,000); Not known (cannot be estimated from the available data).

^a ADR frequency data derived from Clinical Trials or Epidemiological Studies

^b ADRs not observed in clinical trials and frequency calculated using “Rule of 3”, as detailed in SmPC guideline 2009. 6276 patients exposed in clinical trials and epidemiological studies, divided by 3 (Frequency = 1/2092). Note: frequencies differ from those reported in the August 2009 CCDS, as these were not calculated using the formula detailed in the SmPC guideline 2009.

In patients treated at dosages substantially higher than recommended or for prolonged periods of time, the following adverse reactions have been reported rarely: alopecia, reversible liver function disturbances, hepatitis, agranulocytosis, neutropenia and glomerulonephritis. With the exception of agranulocytosis and glomerulonephritis, these also have been reported in patients who were treated with mebendazole at standard dosages (see Section 4.8).

Symptoms

In the event of accidental overdosage, abdominal cramps, nausea, vomiting and diarrhoea may occur.

Treatment

There is no specific antidote. Within the first hour after ingestion, gastric lavage may be performed. Activated charcoal may be given if considered appropriate.

Pharmacotherapeutic classification: Anthelmintic for oral administration, benzimidazole derivatives

ATC code: P02CA01

In vitro and in vivo work suggests that mebendazole blocks the uptake of glucose by adult and larval forms of helminths, in a selective and irreversible manner. Inhibition of glucose uptake appears to lead to endogenous depletion of glycogen stores within the helminth. Lack of glycogen leads to decreased formation of ATP and ultrastructural changes in the cells.

There is no evidence that Ovex is effective in the treatment of cysticercosis.

Absorption

Following oral administration, approximately 20% of the dose reaches the systemic circulation, due to incomplete absorption and to extensive pre-systemic metabolism (first-pass effect). Maximum plasma concentrations are generally seen 2 to 4 hours after administration. Dosing with a high fat meal leads to a modest increase in the bioavailability of mebendazole.

Distribution

The plasma protein binding of mebendazole is 90 to 95%. The volume of distribution is 1 to 2 L/kg, indicating that mebendazole penetrates areas outside the vascular space. This is supported by data in patients on chronic mebendazole therapy (e.g., 40 mg/kg/day for 3-21 months) that show drug levels in tissue.

Metabolism

Orally administered mebendazole is extensively metabolized primarily by the liver. Plasma concentrations of its major metabolites (amino and hydroxylated amino forms of mebendazole) are substantially higher than those of mebendazole. Impaired hepatic function, impaired metabolism, or impaired biliary elimination may lead to higher plasma levels of mebendazole.

Elimination

Mebendazole, the conjugated forms of mebendazole, and its metabolites likely undergo some degree of enterohepatic recirculation and are excreted in the urine and bile. The apparent elimination half-life after an oral dose ranges from 3 to 6 hours in most patients.

Steady-state Pharmacokinetics

During chronic dosing (e.g., 40 mg/kg/day for 3-21 months), plasma concentrations of mebendazole and its major metabolites increase, resulting in approximately 3-fold higher exposure at steady-state compared to single dosing.

Acute oral toxicity of mebendazole in a number of species is low with a large margin of safety. Chronic oral toxicity studies in rats at 40 mg/kg/day and above, showed altered liver weights with some slight centrilobular swelling and hepatocellular vacuolation, and altered testicular weights with some tubular degeneration, desquamation and marked inhibition of spermatogenic activity.

In genotoxicity studies mebendazole was aneugenic in mammalian somatic cells above a threshold plasma concentration of 115 ng/mL, but had no mutagenic or clastogenic activity. In limited long term studies in mice and rats no carcinogenic effects were seen.

Mebendazole has shown embryotoxic and teratogenic activity in pregnant rats and mice at oral doses of 10 mg/kg/day and above and in rats at a single dose of 10 mg/kg, approximately equivalent to the human dose of 100 mg on a body surface area (mg/m²) basis.

Microcrystalline cellulose

Sodium starch glycollate

Talc

Maize starch

Sodium saccharin

Magnesium stearate

Cottonseed oil - hydrogenated

Orange flavour

Colloidal anhydrous silica

Sodium laurilsulfate

Orange yellow S

Purified water*

2-propanol*

* not present in the final product

None known.

36 months.

None.

Blister pack: PVC genotherm glass clear and aluminium foil with heat seal lacquer.

Pack size: 1, 2, 4 and 8 tablets.

Not applicable.

McNeil Products Limited

Foundation Park

Roxborough Way

Maidenhead

Berkshire

SL6 3UG

United Kingdom

PL 15513/0314

01 August 2008

12 April 2011

P