The time taken by Myoprol XL 50 Tablet to start working varies from person to person. Usually, Myoprol XL 50 Tablet starts working within 15 minutes. However, in some patients, it may take up to 2 hours to start working. It starts acting slowly and the maximum or full effect is usually experienced within a span of 1 week. In case you do not feel any difference while taking Myoprol XL 50 Tablet, do not panic. The medicine exerts its beneficial effects when taken for a long time.