How can one dispose of haram money resulting from the purchase of a pharmacy with a loan that was later discovered to be interest-based (ribawi), after borrowing from someone else to repay the original loan?

Whoever takes an interest-bearing loan has committed a grave sin that necessitates sincere repentance, for "the one who repents from sin is like one who has no sin." He is not obligated to dispose of the pharmacy he bought with the interest-bearing loan, as money is fungible. If he repays the loan through any permissible means, his liability is absolved, and the pharmacy and its profits are lawful.