It depends what you mean by “business system”. DHIS2 was originally designed as a generic management information system, so you could easily expand the scope of data captured to include HR, financial and stock data, for example. But this would still just be summary/aggregate data, for management purposes. DHIS2 wasn’t intended to be used as an operational system (ie managing day-to-day patient care at the point-of-delivery), so things like prescribing were definitely out-of-scope.
Since then, DHIS2 has been expanded to include Event Capture and Trackers, which do allow you to collect some operational and patient-level information for specific purposes if needed. But Trackers are much simpler and more limited than Electronic Medical Records (EMR) or e-prescribing systems, so it really depends on the complexity of your operations. For example, if you’re running an ART dispensary with a limited range of medicines, it could be quite feasible to create a DHIS2 Tracker to manage simple prescriptions; but if you’re running a pharmacy that stocks the full range of medicines used in a district hospital, and which receives prescriptions from all over the hospital, then you’ll probably need a much more powerful, feature-rich EMR or e-prescribing system.