INFORMATION FOR HEALTH PROFESSIONALS
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Ornidazole: a-(chloromethyl)-2-methyl-5-nitroimidazole-1-ethanol. Each film-coated tablet contains 500 mg ornidazole.
Tablets also contain maize starch, microcrystalline cellulose, methylhydroxyethylcellulose, methylhydroxypropylcellulose, magnesium stearate, talc, titanium dioxide.
Tiberal 500 mg film coated tablets are white to slightly yellowish, cylindrical, biconvex and imprinted with ROCHE on one side.
Tiberal is effective against Trichomonas vaginalis, Entamoeba histolytica and Giardia lamblia (Giardia intestinalis), and also against certain anaerobic bacteria such as Bacteroides and Clostridium spp., Fusobacterium spp., and anaerobic cocci.
Following oral administration ornidazole is rapidly absorbed. Mean absorption is 90%. Peak plasma concentrations are reached within three hours.
The mean volume of distribution after i.v. administration is 1 litre per kg. Plasma protein binding of ornidazole is about 13%. The active ingredient of Tiberal penetrates the cerebrospinal fluid, the body fluids and the tissues very effectively.
Plasma concentrations are within the range considered to be optimal for the various indications (6 to 36 mg/l).
After repeated administration of 500 mg or 1000 mg every twelve hours to healthy volunteers, an accumulation factor of 1.5-2.5 was calculated.
Ornidazole is mainly metabolised to 2-hydroxymethyl and a-hydroxymethyl metabolites in the liver. Both main metabolites are less active against Trichomonas vaginalis and anaerobic bacteria than the unchanged ornidazole.
The half-life is about thirteen hours. 85% of a single dose is eliminated within the first five days, most of this being metabolised. 4% of the dose is excreted as unaltered substance in the urine.
In patients with liver cirrhosis the elimination half-life is longer (22 versus 14 hours) and clearance lower (35 versus 51 ml/min) than in healthy subjects. The dosing interval should be doubled in patients with severe hepatic impairment.
The pharmacokinetics of ornidazole are unaltered in renal impairment. Dose adjustment is therefore unnecessary in patients with impaired renal function. Ornidazole is removed by haemodialysis. An additional dose of 500 mg of ornidazole should be administered if the daily dose is 2 g/d, or an additional dose of 250 mg ornidazole if the daily dose is 1 g/d, should therefore be administered before the start of haemodialysis.
The pharmacokinetics or ornidazole in neonates and young children are similar to those in adults.
The tablets must always be taken after meals.
There are two possible therapeutic regimens: Single-dose therapy (for acute trichomoniasis); five-day therapy (for chronic forms of trichomoniasis). The tablets should be taken after meals.
(a) Single dose therapy
(b) Five day therapy
| Type of Treatment | Daily Dosage (500 mg tablets) |
|---|---|
| (a) Single-dose | 3 tablets in the evening |
| (b) Five-day therapy | 2 tablets (1 tablet mornings and evenings) |
In all cases, the sexual partner should also be treated using the same
oral dosage so as to avoid reinfection.
The dosage for children is 25 mg per kg bodyweight per day, given in a single dose.
(a) Three-day treatment of patients with amoebic dysentery
(b) Five-to-ten-day treatment for all forms of amoebiasis
| Duration of Treatment | Daily Dosage | |
|---|---|---|
| Adults and children over 35 kg | Children up to 35 kg | |
| a) Three days | 3 tablets in one evening dose Over 60 kg bodyweight: 4 tablets ( 2 tablets mornings and evenings) |
125 mg (1/4 tablet) per 3 kg bodyweight in one dose (equivalent to 40 mg per kg) |
| b) Five to ten days | 2 tablets (1 tablet mornings and evenings) | 125 mg (1/4 tablet) per 5 kg bodyweight in one dose (equivalent to 25 mg per kg) |
| Duration of Treatment | Daily dosage | |
|---|---|---|
| Adults and children over 35 kg | Children up to 35 kg | |
| One to two days | 3 tablets in the evening in one dose | 125 mg (1/4 tablet) per 3 kg bodyweight in one dose (equivalent to 40 mg per kg) |
Prophylaxis: 1500 mg orally, 12 hours before surgery then 500 mg 12-hourly for 3 to 5 days postoperatively.
Tiberal is contraindicated in patients with known hypersensitivity to the medicine or to other nitroimidazole derivatives.
Caution should be exercised in patients with diseases of the CNS, e.g., epilepsy or multiple sclerosis.
The effect of other medicines can be intensified or impaired.
Somnolence, dizziness, tremor, rigidity, poor coordination, seizures, vertigo or temporary loss of consciousness may occur in patients receiving Tiberal. If they occur, such effects may affect tasks requiring alertness including the patient's ability to drive and operate machinery.
Extensive studies in various species have revealed no sign of any teratogenic or foetotoxic action of Tiberal. However, no controlled studies have been carried out in pregnant women. As a matter of principle, Tiberal should not be prescribed in early pregnancy or to nursing mothers except when absolutely necessary.
Mild side effects such as somnolence, headache and gastrointestinal disturbances like nausea and vomiting may occur.
Disturbances of the CNS such as dizziness, tremor, rigidity, poor coordination, seizures, tiredness, vertigo, temporary loss of consciousness and signs of sensory or mixed peripheral neuropathy have been observed in isolated cases. Taste disturbances, abnormal liver function tests and skin reactions have been observed.
In contrast to other nitroimidazole derivatives, ordinazole does not inhibit aldehyde dehydrogenase and is therefore not incompatible with alcohol. However, ornidazole potentiates the effect of coumarin-type oral anticoagulants. The dosage of the anticoagulant has to be adjusted accordingly. Ornidazole prolongs the muscle-relaxant effect of vecuronium bromide.
In cases of overdosage the symptoms mentioned under Undesirable Effects occur in more severe form.
No specific antidote is known. The administration of diazepam is recommended if cramps occur.
This medicine should not be used after the expiry date shown on the pack.
Prescription medicine
Tablets 500 mg, 10's.
Roche Products (New Zealand) Ltd
P O Box 12-492
Penrose
AUCKLAND
Telephone: (09) 633 0700
Telefax: (09) 633 0722
Toll Free: 0800 656 464
2 June 2004
Reference: International Standard Product Information dated March 2004.