He says the sexual encounter with Andrea Constand was consensual.
"I'm thinking this is a dirty old man with a young girl", Cosby said, according to a decade-old deposition read to jurors on Friday by a police officer.
Cosby's career has been derailed by dozens of sexual assault allegations from women stretching back decades, all of which he has denied.
If convicted, Cosby faces up to 10 years in prison and a $25,000 fine.
Cosby replied: "Dead." The final government witness, toxicologist Timothy Rohrig, said the drowsiness and sedation Constand described in her testimony after accepting three blue pills from Cosby in 2004 could have been caused by a drug similar to Quaaludes - or by Benadryl, the over-the-counter allergy medicine Cosby has maintained he gave to Constand that night.
Cosby's lawyers will present his side of the story before jurors get the case.
Prosecutors plan to close their case Friday afternoon after five days of testimony.
Mr Cosby - the legendary comedian and television star - is on trial this week for allegedly sexually assaulting Andrea Constand, a former employee of his alma mater.
When asked if he ever gave the quaaludes to the young women without their knowledge, Cosby responded, "No", according to the deposition testimony.
Cosby insisted in a May interview that he wouldn't testify during his trial, suggesting it's tricky to be absolutely truthful on the stand given all of the expectations for a testimony. She was in the courtroom Friday.
It's the first time Wyatt has spoken at length to reporters since the trial began. Earlier in the trial, Constand's mother testified that she wasn't looking for money from the entertainer.
The spokesman, Andrew Wyatt, said some members of Cosby's family will join him in court as the trial continues. Cosby said he avoided taking the drug himself so as not to become "sleepy".
On Friday, the prosecution put psychologist Veronique Valliere on the stand.
Cosby's lawyers say Valliere's past social-media posts have shown a pro-prosecution bias.
"When offenders act like nothing happened, or try to revise the truth, it may contribute to the victim's fear they won't be believed", Dr. Valliere said. She testified that victims of celebrities are often frightened to come forward because of the backlash.
Constand, then an administrator with Temple University's women's basketball team, was 30 at the time of the alleged crime in 2004.
Friday's deposition excerpts were also expected to include an exchange where Cosby acknowledged using quaaludes, a now-banned sedative, in his pursuit of women for sex.
In the deposition, he recounted a telephone conversation he had with Constand's mother.
Cosby was charged in 2015 with felony aggravated indecent assault shortly before the statute of limitations on Constand's claim expired.
Cosby said it was on her second visit to his home that she rebuffed him. On Wednesday, actress Sheila Frazier and her hairstylist husband, John Atchison, arrived with Cosby.
His interactions with fans outside the courthouse, coupled with a parade of show business friends who have attended the trial in support, have signaled he is intent on repairing his public image.
In his deposition, read in court by Montgomery County detective James Reape and District Attorney Kevin Steele, Cosby said that in the 1970s he had received seven prescriptions for quaaludes from a doctor in Los Angeles, even though he never meant to take them. However, he is said to have repeatedly dodged her questions.
Having Cosby testify also could spoil his lawyers' successful efforts to prevent jurors from hearing about the more than 60 other women who say he assaulted them since the 1960s.
The 79-year-old Cosby has said he will not testify.