Is there a good replacement for Opacorden?

Indeed, exposure to sunlight should be avoided and protected during treatment with Opacorden, as it causes photosensitivity that may persist for several months after stopping treatment. The pharmacist can advise on the selection of a substitute in the sense of the same active substance but from a different manufacturer. You probably mean a completely different drug, because the pharmaceutical equivalent will have exactly the same effects and side effects. However, only a doctor can make a change in treatment. It is difficult to say whether in the case of your uncle there is even a possibility of using other treatments for arrhythmias. Amiodarone (the active ingredient in Opacorden) is an antiarrhythmic drug - talk to your cardiologist about alternative treatment. A molecule similar to amiodarone, but devoid of iodine atoms, is dronedarone. However, it is difficult for me to answer whether in the individual case of your uncle it would be the right choice, moreover, the treatment is rather expensive: https://www.gdziepolek.pl/substancje/dronedarone https://www.gdziepolek.pl/kategorie/leki-na-arytmie There is no such drug as "Minurit", I think you mean Milurit - this drug actually comes in a dose of 100 mg and 300 mg. Milurit 100 mg contains 100 milligrams of the active substance - allopurinol. Milurit 300 mg contains 300 milligrams of the active substance allopurinol. So, the difference lies in the strength of the drug - a higher dose contains three times more allopurinol: https://www.gdziepolek.pl/produkty/49202/milurit-tabletki/apteki/w-warszawie