Drug information of Porfimer

Porfimer


The purified component of hematoporphyrin derivative, it consists of a mixture of oligomeric porphyrins.

Mechanism of effect

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.

Pharmacodynamic

Tumor selectivity in treatment occurs through a combination of selective retention of porfimer and selective delivery of light.

Pharmacokinetics

Half-Life: 17 days (first dose); 30 days (second dose); retained longest in tumors, skin, and reticuloendothelial organs

Peak Plasma Concentration: 15 mcg/mL

Protein Bound: 90%

Vd: 0.49 L/kg

Clearance: 0.051 mL/min/kg

Dosage

Adult

Esophageal Cancer, Endobronchial NSCLC

2 mg/kg IV over 3-5 minutes 

Follow by corresponding spectrum of laser light 40-50 hours after injection, then again 96-120 hours after injection; separate repeat courses by 30 days; not to exceed 3 courses

Ablation of High-grade Dysplasia in Barrett's Esophagus

2 mg/kg IV over 3-5 minutes 

Follow by corresponding spectrum of laser light 40-50 hours after injection, then again 96-120 hours after injection; separate repeat courses by 30 days; not to exceed 3 courses

Pediatric

Safety and efficacy not established

Alerts

Separate from radiotherapy by 2-4 wk

Avoid sunlight following injection

Esophageal stricture reported within 6 months of initiating treatment (usually within 6 months of treatment)

Inflammation resulting from treatment may obstruct airway (not for use in patients with esophageal tumors eroding into the trachea or bronchial tree

Potentially fatal gastrointestinal and esophageal necrosis and perforation may occur following treatment

May experience substernal chest pain from inflammatory responses within the treatment area

Risk of hemorrhage increased in patients esophageal varices or tumors eroding into pulmonary blood vessels

Ocular discomfort reported

Photosensitivity reactions reported in patients exposed to direct sunlight or bright indoor light

Thromboembolism reported, particularly in patients with other risk factors (eg, advanced cancer, postsurgery, prolonged immobilization, CV disease)

Points of recommendation

  • Tell all of your health care providers that you take Porfimer. This includes your doctors, nurses, pharmacists, and dentists.
  • If you have upset stomach, throwing up, diarrhea, or are not hungry, talk with your doctor. There may be ways to lower these side effects.
  • Have blood work checked as you have been told by the doctor. Talk with the doctor.
  • You may get sunburned more easily. Avoid sun, sunlamps, bright indoor lights, and tanning beds for as long as you were told by your doctor. Wear clothing and eyewear that protects you from the sun. Sunscreens will not protect you.
  • Bright lights may bother you for some time after using Porfimer. Wear sunglasses for as long as you were told by your doctor.
  • People using Porfimer may get skin reactions where Porfimer is used. These reactions may include blisters, burning, itching, redness, swelling, or a warm feeling. Call your doctor if you have skin reactions that are very bad, bother you, or do not go away.
  • Talk with your doctor if you will need to be still for long periods of time like long trips, bedrest after surgery, or illness. Not moving for long periods may raise your chance of blood clots.
  • Call your doctor right away if you have signs of a blood clot like chest pain or pressure; coughing up blood; shortness of breath; swelling, warmth, numbness, change of color, or pain in a leg or arm; or trouble speaking or swallowing.
  • Tell your doctor if you are pregnant or plan on getting pregnant. You will need to talk about the benefits and risks of using Porfimer while you are pregnant.
  • Tell your doctor if you are breast-feeding. You will need to talk about any risks to your baby.

Pregnancy level

Group c - Not adequate studies in pregnant women


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