Sinner's was the first of two high-profile cases in tennis in quick succession, with women's world number two Iga Swiatek handed a one-month suspension in November after a positive test for the angina medication trimetazidine.
"Obviously having just won the Australian Open, to miss three months of the Tour and therefore to be eligible to play at Roland Garros, the timing couldn't have been any better for Sinner, but I still think it leaves a pretty sour taste for the sport.
Sinner has reached a settlement with the World Anti-Doping Agency (WADA) over two positive drugs test last year.
In September, Sinner said he was "very disappointed and also surprised" when WADA appealed against an independent tribunal's ruling of "no fault or negligence" for his two positive tests.
WADA accepts that Sinner "did not intend to cheat, and that his exposure to clostebol did not provide any performance-enhancing benefit and took place without his knowledge as the result of negligence of members of his entourage".
