Photofrin - General Information
The purified component of hematoporphyrin derivative, it consists of a mixture of oligomeric porphyrins. It is used in photodynamic therapy (hematoporphyrin photoradiation); to treat malignant lesions with visible light and experimentally as an antiviral agent. It is the first drug to be approved in the use of photodynamic therapy in the United States. [PubChem]
Pharmacology of Photofrin
Photofrin is a photosensitizing agent used in the photodynamic therapy (PDT) of tumors. Photofrin is indicated for the palliation of patients with completely obstructing esophageal cancer, or of patients with partially obstructing esophageal cancer who cannot be satisfactorily treated with Nd:YAG laser therapy, reduction of obstruction and palliation of symptoms in patients with completely or partially obstructing endobronchial nonsmall cell lung cancer (NSCLC), and the treatment of microinvasive endobronchial NSCLC in patients for whom surgery and radiotherapy are not indicated. The cytotoxic and antitumor actions of porfimer are light and oxygen dependent. Tumor selectivity in treatment occurs through a combination of selective retention of porfimer and selective delivery of light.
Photofrin for patients
There have been no formal interaction studies of PHOTOFRIN and any other drugs. However, it is possible that concomitant use of other photosensitizing agents (e.g., tetracyclines, sulfonamides, phenothiazines, sulfonylurea hypoglycemia agents, thiazide diuretics, and griseofulvin) could increase the photosensitivity reaction.
PHOTOFRIN PDT causes direct intracellular damage by initiating radical chain reactions that damage intracellular membranes and mitochondria. Tissue damage also results from ischemia secondary to vasoconstriction, platelet activation and aggregation and clotting. Research in animals and in cell culture has suggested that many drugs could influence the effects of PDT, possible examples of which are described below. There are no human data that support or rebut these possibilities.
Compounds that quench active oxygen species or scavenge radicals, such as dimethyl sufloxide, b-carotene, ethanol, formate and mannitol would be expected to decrease PDT activity. Preclinical data also suggest that tissue ischemia, allopurinol, calcium channel blockers and some prostaglandin synthesis inhibitors could interfere with PHOTOFRIN PDT. Drugs that decrease clotting, vasoconstriction or platelet aggregation, e.g., thromboxane A2 inhibitors, could decrease the efficacy of PDT. Glucocorticoid hormones given before or concomitant with PDT may decrease the efficacy of the treatment.
PHOTOFRIN is contraindicated in patients with porphyria or in patients with known allergies to porphyrins.
PDT is contraindicated in patients with an existing tracheoesophageal or bronchoesophageal fistula.
PDT is contraindicated in patients with tumors eroding into a major blood vessel.
Additional information about Photofrin
Photofrin Indication: Indicated in the treatment of esophageal cancer.
Mechanism Of Action: Cellular damage caused by porfimer is a consequence of the propagation of radical reactions. Radical initiation may occur after porfimer absorbs light to form a porphyrin excited state. Spin transfer from porfimer to molecular oxygen may then generate singlet oxygen. Subsequent radical reactions can form superoxide and hydroxyl radicals. Tumor death also occurs through ischemic necrosis secondary to vascular occlusion that appears to be partly mediated by thromboxane A2 release.
Drug Interactions: Not Available
Food Interactions: Not Available
Generic Name: Porfimer
Synonyms: DHE; DHP ether; Dihematoporphyrin ether; Porfimer sodium
Drug Category: Dermatologic Agents; Antineoplastic Agents; Antiviral Agents
Drug Type: Small Molecule; Approved; Investigational
Absorption: Not Available
Toxicity (Overdose): Not Available
Protein Binding: ~90%
Biotransformation: Not Available
Half Life: 10-452 hours
Dosage Forms of Photofrin: Powder, for solution Intravenous
Chemical IUPAC Name: Not Available
Chemical Formula: C68H74N8O11
Porfimer on Wikipedia: https://en.wikipedia.org/wiki/Porfimer
Organisms Affected: Humans and other mammals