Porfimer sodium
Porfimer sodium
Porfimer sodium
( POOR-fih-mer)
Pregnancy Category: C Photofrin (Rx)

Classification: Antineoplastic, miscellaneous

Action/Kinetics: A photosensitizing drug used in the photodynamic therapy (PDT) of tumors. The effects are both light and oxygen dependent. Following IV injection, porfimer is retained for a prolonged period of time in tumors, skin, and organs of the reticuloendothelial system (including liver and spleen). Drug administration is followed by illumination with 630 nm of light, which causes a photochemical (not a thermal) effect. Cellular damage is the result of propagation of radical reactions, including formation of superoxide and hydroxyl radicals. Tumor death may also occur through ischemic necrosis secondary to vascular occlusion that is likely mediated through release of thromboxane A ₂. t 1/2, elimination: 250 hr. Mean plasma levels after 48 hr: 2.6 mcg/mL. About 90% bound to serum proteins.

Uses: Completely obstructing esophageal cancer or those with partially obstructing esophageal cancer who cannot be treated satisfactorily with Nd:YAG laser therapy. Microinvasive endobronchial non-small cell lung cancer where surgery and radiotherapy are not indicated.

Contraindications: Known allergies to porphyrins. Use of PDT in existing tracheoesophageal or bronchoesophageal fistulas or tumors eroding into a major blood vessel. Lactation.

Special Concerns: Those treated with porfimer sodium will be photosensitive and must observe precautions to avoid exposure of the skin and eyes to direct sunlight or bright indoor lighting. Use with extreme caution in esophageal varices and where treatment-induced inflammation can obstructe the main airway. Safety and efficacy have not been determined in children.

Side Effects: Side effects listed are those possible from porfimer PDT. Over 95% of clients experienced one or more side effects. Location of the tumor was predictive for three side effects: esophageal edema if the tumor was in the upper one-third of the esophagus, atrial fibrillation if in the middle third, and anemia if in the lower third. Clients with large tumors (greater than 10 cm) were more likely to manifest anemia. Some GI, CV, and respiratory side effects may be due to mediastinal inflammation.
GI: Constipation, N&V;, abdominal pain, dysphagia, esophageal edema, esophageal tumor bleeding, hematemesis, dyspepsia, esophageal stricture, diarrhea, eructation, esophagitis, melena, esophageal perforation, gastric ulcer, ileus, jaundice, peritonitis. Respiratory: Pleural effusion, dyspnea, pneumonia, pharyngitis, respiratory insufficiency, coughing, tracheoesophageal fistula, bronchitis, bronchospasm, respiratory distress, laryngotracheal edema, pulmonary hemorrhage, respiratory failure pneumonitis, pulmonary edema, stridor. CNS: Insomnia, anorexia, confusion, anxiety. CV: Atrial fibrillation, cardiac failure, tachycardia, hypertension, hypotension, angina pectoris, bradycardia, MI sick sinus syndrome, SVT. Body as a whole: Fever, pain, chest pain, back pain, peripheral edema, asthenia, substernal chest pain, generalized edema, surgical complications, weight decrease, dehydration. Ophthalmic: Abnormal vision, diplopia, eye pain, photophobia, ocular senstivity, photosensitivity reaction. Miscellaneous: Anemia (due to tumor bleeding), moniliasis, UTI, sepsis.

Overdose Management: Symptoms: Photosensitivity. Increased symptoms and damage to normal tissue following an overdose of light. Treatment: Treat photosensitivity by protecting eyes and skin from direct sunlight or bright indoor light for 30 days. Then, test clients for residual photosensitivity. Porfimer is not dialyzable.

Drug Interactions: Allopurinol / Effect of porfimer Beta-carotene / PDT activity Calcium channel blockers / Effect of porfimer Ethanol / PDT activity Glucocorticoids / PDT activity Griseofulvin / Photosensitivity reaction Hypoglycemic drugs / Photosensitivity reaction Mannitol / PDT activity Phenothiazines / Photosensitivity reaction Prostaglandin synthesis inhibitors / Effect of porfimer Sulfonamides / Photosensitivity reaction Tetracyclines / Photosensitivity reaction Thiazide diuretics / Photosensitivity reaction

How Supplied: Cake or Freeze-Dried Powder for Injection: 75 mg.

Dosage
?IV Injection Esophageal cancer.
The first stage is IV injection of porfimer, 2 mg/kg, given over 3-5 min. Illumination with laser light (300 J/cm of tumor length at a wavelength of 630 nm) 40-50 hr later is the second stage of therapy. A second laser light application may be given 96-120 hr after the porfimer injection, which is preceded by gentle debridement of residual tumor. This regimen may be repeated 30 days after the initial therapy; up to three courses of treatment (each separated by a minimum of 30 days) may be given.