Action And Clinical Pharmacology: Mechanism of Action: Praziquantel induces a rapid contraction of schistosomes by a specific effect on the permeability of the cell membrane. The drug further causes vacuolization and disintegration of the schistosome tegument. The effect is more marked on adult worms compared to young worms. An increased calcium influx may play an important role.
Secondary effects are inhibition of glucose uptake, lowering of glycogen levels and stimulation of lactate release. The action of praziquantel is limited very specifically to trematodes and cestodes; nematodes (including filariae) are not affected.
After oral administration, praziquantel is rapidly absorbed (approximately 80%), subjected to a first pass effect, metabolized and eliminated by the kidneys. Maximal serum concentration is achieved 1 to 3 hours after dosing. The half-life of praziquantel in serum is 0.8 to 1.5 hours.
Indications And Clinical Uses: For the treatment of infections due to the following species of schistosoma: (S. haematobium, S. japonicum, S. mansoni, and S. mekongi), and infections due to the liver flukes C. sinensis/O. viverrini. (Approval of this indication was based on studies in which the two species were not differentiated.)
Contra-Indications: Patients who have previously shown hypersensitivity to the drug.
Since parasite destruction within the eye may cause irreparable lesions, ocular cysticercosis should not be treated with praziquantel.
Manufacturers’ Warnings In Clinical States: Information for the Patient: There may possibly be effects on vigilance. Patients should be warned not to drive a car and not to operate machinery on the day of praziquantel treatment and during the subsequent 24 hours as their ability to do so may be temporarily impaired by the use of praziquantel.
Children: Safety in children under 4 years of age has not been established.
Pregnancy: No adequate and well-controlled studies have been conducted with praziquantel in pregnant women (see Precautions).
Precautions: General: Nephrotoxic effects of praziquantel have not been observed. Since 80% of praziquantel and its derivatives are excreted in the kidneys, excretion may be delayed in patients with impaired renal function.
Caution should be taken in patients with uncompensated liver insufficiency or with hepatosplenic schistosomiasis. Because of reduced drug metabolization in the liver, considerably higher and longer lasting concentrations of unmetabolized praziquantel can occur in the vascular system and/or collateral circulation, leading to prolonged plasma half-life. If necessary, the patient may be hospitalized for the duration of treatment. Mild increases in liver enzymes have also been reported in some patients.
Patients suffering from cardiac irregularities should be monitored during treatment.
When schistosomiasis or fluke infection is found in patients living in or coming from areas with endemic human cysticercosis, it is advisable to hospitalize the patient for the duration of treatment.
Pregnancy: An increase in the abortion rate was found in rats at 3 times the single human therapeutic dose. Although animal reproduction studies have not brought to light any evidence that the mother or the unborn child might be harmed, these studies are not always predictive of human response. Praziquantel should not be used in pregnancy unless clearly needed.
Lactation : Praziquantel appears in the milk of nursing women at a concentration of 20 to 25% that of maternal serum. Breast-feeding should be suspended for the day(s) of treatment and the following 72 hours.
Drug Interactions: Dexamethasone, when taken simultaneously, can lead to lower concentrations of praziquantel in blood.
Concomitant administration of drugs increasing the activity of drug metabolizing liver enzymes (cytochrome P450), i.e., antiepileptic drugs, may reduce plasma levels of praziquantel.
Adverse Reactions: Adverse reactions vary according to dose and duration of praziquantel medication. Furthermore, they are dependent on the parasite species, extent of parasitization, duration of infection and localization of the parasites in the body.
Apart from these conditions, abdominal pain, inappetence, nausea, vomiting, headache, vertigo, weakness, dizziness, drowsiness, malaise, myalgia, urticaria or elevated temperature may occur occasionally to frequently.
Depending on the kind of infection the following additional adverse reactions have been observed in single cases: bloody diarrhea, seizure, arrhythmia, generalized hypersensitivity (including polyserositis).
Mild increases in liver enzymes have been reported in some patients.
It is often not clear whether the complaints reported by patients or the undesired effects recorded by the physician are caused by praziquantel itself (direct relation), or may be considered to be an endogenous reaction to the death of the parasites (indirect relation) or are symptomatic observations of the infestation (no relation). It may be difficult to differentiate between the possible variations.
Symptoms And Treatment Of Overdose: Symptoms and Treatment: No data are available regarding overdosage in humans. In the event of an overdose, a fast-acting laxative is recommended. In rats and mice the acute oral LD50 was approximately 2 500 mg/kg and in dogs the oral LD50 was less than 200 mg/kg.
Dosage And Administration: Doses should be individualized depending on the diagnosis. Based on clinical experience, the following dosages are recommended.
Schistosomiasis: 3Â´20 mg/kg body weight as a 1-day treatment. The tablets should be swallowed whole with a little liquid, preferably during or after meals. Keeping the tablets (or segments thereof) in the mouth may reveal a bitter taste which can cause gagging or vomiting.
With single daily doses it is recommended to take the tablets in the evening. If ingestion of tablets several times a day is prescribed, the interval between administration should be at least 4 hours and not more than 6 hours.
When broken, each of the 4 segments contains 150 mg of active ingredient so that the dosage can be easily adjusted to the patient’s body weight.
Children: Safety and efficacy in children under 4 years of age has not been established (see Warnings).
Availability And Storage: Each white, film-coated, oblong tablet, with three scores on both sides and engraved BAYER on one side and LG on the other, contains: praziquantel 600 mg. Nonmedicinal ingredients: cornstarch, magnesium stearate, microcrystalline cellulose, polyvidone 25, sodium lauryl sulfate, polyethylene glycol 4000, methylhydroxypropylcellulose and titanium dioxide. When broken, each of the four segments contains 150 mg of the active ingredient so that the dosage can be easily adjusted to the patient’s body weight. Segments are broken off by pressing the score (notch) with thumbnails. If one quarter of a tablet is required, this is best achieved by breaking the segment from the outer end. Bottles of 6. Store at room temperature below 30Â°C. Protect from light and excessive humidity.
BILTRICIDE® Bayer Praziquantel Anthelmintic
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