The tribunal, chaired by barrister Shahid Hamid and includes former captain Intikhab Alam and doping expert Waqar Ahmed, is hearing the case after the pair tested positive for performance enhancing banned steroid nandrolone.
"During the second hearing Akhtar and Asif recorded their statements. Asif came alone and was questioned for over an hour while Akhtar was accompanied by doctor Nauman Niaz and stayed for the same duration," a Pakistan Cricket Board spokesman said on Friday.
Niaz is his personal physician.
Hamid is expected to release a statement about the proceedings later Friday.
Akhtar and Asif, who both pleaded innocence, were sent home from the Champions Trophy in India last week. Their 'B' samples are yet to be examined.
During the preliminary hearing, which lasted around four hours last week, the tribunal handed medical reports to both the pacemen and asked them to record their statements in the next hearing.
Akhtar, who returned to cricket only last month after missing Pakistan's Test series in England with an ankle injury, said he never cheated in cricket.
"I have not knowingly taken any performance enhancing drugs and would never cheat my teammates or opponents in this way," the 31-year-old Akhtar has said.
Both Akhtar and Asif face a two-year ban, the minimum for a first offense under International Cricket Council doping rules. However, the PCB said it will take its own decision since the tests were conducted internally.
The PCB has also said that if both players demand tests on their B samples, they would be given the opportunity once the tribunal finished its work.
The tribunal is expected to submit its findings in two weeks.