How does photodynamic therapy (PDT) work?
One course of PDT consists of one injection of PhotoBarr plus one or two laser light applications. To increase your response rate, you may need up to three PDT courses, separated by at least 90 days.
PhotoBarr injection: You will receive one intravenous injection of PhotoBarr(2 mg per kg of body weight) 40 to 50 hours before laser light treatment. The reddish-brown solution is slowly injected, over 3 to 5 minutes, into a vein.
Laser light treatment: Your doctor will apply the red laser light(not a burning laser) to the involved area using an endoscope (a device used to see inside certain parts of the body).. You may receive a second laser light treatment 96-120 hours after the initial injection of PhotoBarr. You will be given a sedative along with a local anaesthetic, to minimise discomfort
If you miss the laser light treatment
Both the medicine and laser light are necessary for the therapy to work. If you realise that you have missed your appointment for the laser treatment, contact your doctor immediately. Your doctor will decide how to proceed with the treatment.
How to prevent a photosensitivity reaction
Photosensitivity reactions are very common side effects of PhotoBarr (affecting more than 2 users in 3). They consist mainly of sunburn-like reactions, mild redness on exposed skin, usually the face and hands. For 90days following your PhotoBarr injection, you must take precautions to avoid exposure of skin and eyes to light. If you have liver problems, this period might be longer.
Since PhotoBarris activated by the red part of light, sunscreens for UV (ultraviolet) light will not protect you against photosensitivity reactions.
Direct sunlight:
Before you go to receive your PhotoBarrinjection, check that there are adequate shades and curtains in your home to keep out bright sunlight. If you go out during daylight hours (even on cloudy days and while travelling in a vehicle), you should take the following precautions:
- cover as much skin as possible by wearing a long-sleeved shirt, trousers, socks, shoes, gloves and a wide brimmed hat
- protect your eyes with dark sunglasses.
- remember to take protective clothing and sunglasses with you to your appointment, as you will be photosensitive once the injection has been given.
Indoor light:
Avoid direct exposure to bright indoor lights, including dental lamps, operating room lamps, unshaded light bulbs at close proximity or neon lights.
However, to speed up the natural process of inactivating the medicine in your body, it is good to expose the skin to normal levels of indoor light. You do not need to stay in a darkened room.
Photosensitivity skin test
About 90 days after the PhotoBarr injection, you should test the photosensitivity of your skin as follows:
Cut a 2-inch hole in a paper bag, put it on your hand or elbow (not your face).
Expose a small area of skin to sunlight for 10 minutes.
Check for the appearance of red marks, swelling or blistering after one day.
- if none of these appear on the exposed area, then you can gradually return to your normal outdoor activities, limiting exposure to the sun during the midday hours.
- if any of these signs are seen, then continue to protect yourself from bright light for 2 more weeks, then repeat the skin test. If you go on holiday to an area with more sunshine, remember to repeat the skin test, especially if some areas of skin have not been exposed to sunlight since your PhotoBarr treatment.