Verteporfin, which is marketed as Visudyne, is a benzoporphyrin derivative used in photodynamic therapy. It functions by eliminating abnormal blood vessels within the eye, which are associated with the wet form of macular degeneration. When administered, the medication accumulates in these vessels, whereby it is stimulated by non-thermal red lighting on a wavelength of 689nm. In the presence of oxygen, highly reactive short-lived oxygen radicals are produced, and these radicals result in damage to the endothelium. This blocks the abnormal blood vessels in question.
In addition to its use in the fight against wet-form macular degeneration, Verteporfin can also be used as an off-label treatment for central serious retinopathy, a disease which can cause visual impairment due to a leakage of fluid underneath the retina, which accumulates beneath the central macula.
The most common side effects patients have experienced when taking Verteporfin include slight changes in vision, irritation of the eyelids (including redness, swelling and itching), headaches, dry eyes, feeling weak or tired, a mild skin rash, itching, constipation, nausea, muscle weakness, flu-like symptoms (such as fever, body aches, sore throat and chills) and reactions at the injection sight (bleeding, swelling, itching and general pain).
Treatment with Verteporfin is a two-step process, and patients may experience these side effects at different stages of treatment. Although these side effects may cause temporary discomfort, any issues should resolve themselves with time. If side effects persist for a prolonged period or seem to be getting worse, the patient is urged to contact their doctor, GP or eye specialist in order to ascertain if there have been any unexpected problems.
Most patients will only experience low-level side effects during treatment with Verteporfin, which can be expected during eye surgery. Because the benefit of the drug outweighs the inconvenience or discomfort of the side effects, most patients are happy to experience temporary issues in order to tackle their problematic macular degeneration.
Ocular (vision) side effects known to occur include decreased visular acuity, dlepharitis, conjunctivitis, itchy eyes, vision loss, lacrimation disorder, mild stromal haze, diplopia, visual field defects and exudation.
If these side effects are present, you should tell your ophthalmologist or healthcare provider immediately. In the event of these side effects occurring shortly after treatment, when you are no longer at the treatment center, you should consider contacting the FDA for advice or the emergency services if you feel like you may require treatment.
In rare circumstances, retinal detachment has been reported. Severe vision decrease has also been reported in up to 5% of patients with one week of treatment, although the majority of these patients go on to fully recover. A small number of patients only experienced a partial decrease, of which the percentage is negligible.
Some patients may encounter gastrointestinal side effects which can include acid reflux and nausea. In rare instances patients have been known to experience elevated liver function tests, although there is no documented evidence that Verteporfin contributes to long-term liver problems, and most patients’ liver function returns to normal shortly after treatment.
Pain caused by Verteporfin infusion could potentially be related to transient neutropenia. A small study describes four patients who experienced pain on infusion, and the average neutrophil counts decreased from 4589/mm3 to 1688/mm3 after infusion. Five control patients in the same study experienced no significant pain, and had no significant change in neutrophil counts post-infusion.
As with other medications used during eye surgery, Verteporfin should only be used as prescribed by a qualified physician who specializes in eye problems. Patients who take more than the advised dose are advised to seek medical assistance, although this should not happen because the medication should only be administered by a qualified professional in a suitable clinic.
For the treatment of adult macular degeneration, the drug is typically administered intravenously at a dose of 6mg per m2 body surface area, over a 10 minute period. After the substance has been injected, it is photoactivated by at least 80 seconds of laser light administration (at a level of 689nm). Laser light activation typically commences 15 minutes after Verteporfin has been infused.
Patients who are also suffering from bilateral lesions are advised to undergo the same level of treatment. If no issues arise, then the patient may be treated in both eyes concurrently, with treatment on the second eye starting no later than 20 minutes after Verteporfin infusion of the first. This is to ensure that both eyes recover at the same level, to avoid one eye being in better condition than the other, as this can cause excess strain on the eye.
Many medications interact with other chemicals or medicines in the body, and this can change the efficacy of the medication or even result in unwanted side effects. Because drug interactions have the potential to cause dangerous reactions in the patient, it is imperative that patients keep a detailed list of all medicines they are currently taking. This extends to over the counter remedies and herbal supplements, as well as prescribed drugs.
Below is a list of medications which are known to have majorly interacted with Verteporfin in a negative way. Patients who are currently undergoing treatment with one or more of these medications are advised to tell their doctor before undergoing eye treatment with Verteporfin:
In addition to any prescription medications or non-prescription remedies, patients are advised to notify their doctor if they are taking anything which may affect blood pressure, blood flow or drowsiness. This can include recreational substances, such as alcohol, as well as sleeping pills, muscle relaxants and cough suppressants. Some medications may contain ingredients designed to cause drowsiness without the patient realising, which is why it is important to be upfront with healthcare providers about all substance use.
Before Verteporfin is administered, a number of standard precautions should be taken so as to avoid extravasation. Examples of such precautions include, but are not limited to:
Extravasation of Verteporfin can cause severe pain, swelling, discoloration and inflammation at the injection site, particularly if the area is exposed to light. In the event of extravasation occurring, it is important that the infusion is immediately stopped. The area of extravasation needs to be completely protected from direct light until discoloration and swelling have faded. This is to prevent local burns, which can be severe. A cold compress should be applied to the site of injection in this instance, and oral medications for pain relief, such as Ibuprofen, can be administered in order to reduce inflammation and discomfort.
Following treatment with Verteporfin, great care should be taken to avoid the exposure of skin and eyes to direct sunlight or bright interior lighting for at least five days. Patients are advised to use low-level lighting and wear UV protective sunglasses, googles or visors.
Patients who experience a severe decrease in vision with a week of Verteporfin treatment should not be retreated, unless their vision subsequently recovers to pre-treatment levels, and the potential benefits of retreatment outweigh the risks. These risks should be carefully considered by the operating physician in order to avoid any permanent damage or complete loss of vision.
Studies have found that Verteporfin is excreted into human breastmilk after standard infusion levels of 6mg per mg2. Breast milk levels of Verteporfin were found to be up to 66% of corresponding levels of plasma, declining within 24 hours, but potentially persisting for at least 48 hours. Although the effects of Verteporfin on nursing infants is currently unknown, mothers may decide to postpone treatment or temporarily discontinue nursing at their discretion.
Verteporfin is supplied in 5mg and 25 mg glass bottles. Because this medication is light-sensitive, it should be stored in desiccated powder form and out of direct sunlight at a temperature of -20C. Before use, it should be prepared by a qualified healthcare professional.
Once past its use by date, Verteporfin should be disposed of carefully as a hazardous material. This means that it should not simply be thrown in a standard bin or poured down a sink, drain or toilet. It should be disposed of in a safe manner so that children or pets cannot access it. Because Verteporfin is typically administered in a hospital or clinic, patients may not need to worry about the disposal of excess or unused quantities of the medicine, as a qualified healthcare professional will ensure of its correct destruction.
While treatment with Verteporfin is greatly beneficial to those experiencing wet-form macular degeneration – the elderly in particular – it is not without its risks to patients who fail to disclose any other medications they are currently taking. It is designed to destroy abnormal blood vessels which would otherwise cause deteriorating eyesight, and is incredibly effective when used properly, in conjunction with laser therapies.
When administered correctly, most patients only experience minor discomfort, which pales in comparison to the positive effects of saving their eyesight at its current level. In order to achieve the best possible results with this medication, doctor and patient should work together to ascertain the best frequency of use. Some patients may only need a one off treatment to alleviate symptoms of macular degeneration, whereas other may require repeated ongoing treatment, typically once every three months.