"We did receive a call from Charlie's house this morning, asking for medical assistance and advice," the couple tell PEOPLE in a statement, "and immediately insisted the caller dial 911. Dr. Nassif also immediately called 911."
Sheen, 45, was taken by ambulance to Cedars-Sinai Medical Center, where his parents Martin and Janet Sheen soon arrived.
"As longtime friends, we are obviously very concerned about his well-being," say Nassif and Maloof-Nassif, who appear on Real Housewives of Beverly Hills. "Our thoughts and prayers are with him and his family right now and we wish him a speedy recovery."