Composition
Radagel is 0.1% Radachlorin gel for external application. Radagel comes in 25-g vials. Each vial contains 25 mg (1 mg/g) of
active chlorine substance, i.e. sodium salt. Twenty-five-gram vials are supplied in boxes with instructions enclosed. Boxes of 10
vials are provided with one instruction per box.
Indications
Radagel is applied to destroy malignant tumors of various origins. Radagel can be used both independently from and in
combination with cytotoxic chemotherapy and radiotherapy to potentiate the therapeutic effect produced by them. Radagel also
prevents implantation metastases due to its intraoperative effect on tissues.
Mechanism of Action
Radagel is a superpotent high-selective photosensitizer applied in photodynamic therapy (PDT). Radagel is rapidly
(within a time span of 30 min to 5 hours) accumulated in malignant tumors. The contrast index ranges from 3 to 40, depending on
the type of a tumor. Radagel is effective when excited by optical radiation at a wavelength of 662+5 nm. As a result, it starts to
actively generate cytotoxic elements (such as singlet oxygen) in the tumor. Radachlorin is a highly cytophototoxic compound aimed
at various types of tumor cells. Thus, it is considered to be able to prevent tumor growth. The absence of dark cytotoxicity and
the rapid elimination of this compound from the skin of mucous membranes make Radagel especially beneficial in PDT. The use of
Radagel causes no damage to healthy organs and tissues, nor does it make skin hypersensitive to daylight. Compounds for
chemotherapy and radiotherapy are able to increase the clinical effect produced by PDT. The results obtained in experiments carried
out on animals showed that Radagel decreases the mobility of animals to some extent. However, other functional parts of the central
nervous system were not affected.
Dosage and Application
Radagel is used to treat both adults and children with superficial nodal and erosive malignant tumors of the 1st and 2nd
stages (epitheliomas, basaliomas, etc.). Thirty minutes before the PDT session, Radachlorin, 0.1% gel for external application,
is applied at a dose of 0.2 g per 1 cm? of the surface (0.2 mg of radachlorin) and covered with a waterproof band. After that,
the excessive gel is removed, and the patient is exposed to 662+5 nm laser radiation at a radiation density of 200 to 500 J/cm?.
The exposure time is 3 to 60 min.
Contraindications
Hypersensitivity to any component of the compound.
Precautions
After the use of Radagel, the patient should not be exposed to bright light (especially daylight) within 12 hours. Furthermore,
he or she should prevent their eyes from bright light within the following 12 hours. It is also recommended that the patient should
avoid watching TV during first hours after the use of the compound. No experiments have been carried out during pregnancy.
Radachlorin, like any other drugs, should not be used during pregnancy, especially in the early months of pregnancy, unless it is
doubtless that the expected benefit for the mother stands higher than the potential risk of her expected child.
Side Effects
In some cases, the use of Radagel may raise the patient's temperature up to 37.0°C to 38.5°Ñ or make him or her feel feverish.
Usually, these side effects disappear within 30 min. To prevent these effects, one should take antipyretic, analgetic, and
antihistaminic compounds. It is also reported that skin becomes hypersensitive to radiation after the use of Radagel.
Overdosage
Currently, there is not much information about radachlorin overdosage. Experiments on animals showed that LD10 totals 119 mg
per kg, which exceeds the recommended dosage by a factor of 100 to 500. Intoxication causes severe cardiopulmonary decompensation.
In the case of overdosage, one should undergo a corresponding kind of symptomatic supporting therapy.
Storage Conditions
Radagel, gel for external application, should be kept in a cool dark place.
Pharmakokinetics and Metabolism in Experiments on Animals
Thirty minutes after the intravenous administration at a dose of 20 mg/kg, radachlorin shows the maximum of concentration in the
tumor (up to 0,3 mM) and remains there for up to 5 hours. The contrast range of accumulation becomes at a maximum after 3 hours.
For superficial tumors, the accumulation contrast is 3 for the tumor/muscular tissues and 4 for the tumor/skin tissues. After 24
hours, 98 percent of the compound is eliminated out of the body (the semi-elimination period is 12 hours). Radachlorin is eliminated
mainly from the body due to liver metabolism. Less than 2 percent of the administered dose goes out unchanged with urine.
The blood plasma protein binding amounts to 90 to 95 percent.
