The winner of MTV's reality show Splitsvilla 2, who was believed to be part of a MMS scandal, was nominated via the captain's vote.
Pradhan recently survived a pregnancy scare but has not been keeping well these days.
The other two housemates nominated were Seema Parihar and Sameer Soni.
Exclusive: Meet the Bigg Boss 4 contestants
Wild days ahead on Bigg Boss 4!
Sena: Why do we need Pak people in Bigg Boss?
Dhoni-Sakshi to tie knot at Vasundhara's farmhouse
Thackeray: Come what may, won't allow Bigg Boss