Since you took out the loan for business purposes only, you can claim the interest as a business expense.
You do not need to itemize deductions to claim this as a business expense. Enter them in the Interest Expense interview under Business income and Expenses > Business Expenses > Other Common Business Expenses
The fact that the loan is secured by your primary residence (or another property) does not disqualify you from claiming the interest as a business deduction.
From Publication 535 Business Expenses:
"The allocation of loan proceeds and the related interest is not generally affected by the use of property that secures the loan."