A young woman has to "block out" imagining what could have happened to her at the hands of a family friend who slipped drugs into her hot chocolate.

Wheelchair-bound Peter Brian Hastie, 46, was sentenced to six months home detention this week after pleading guilty in Christchurch District Court to a charge of stupefying the woman, as well as three charges of unlawfully possessing semi-automatic firearms.

The woman, 19, who has name suppression, was 17 when the man - someone she had known since childhood - drugged her hot chocolate with medication to treat insomnia and other chemical imbalances in the brain.

The last thing she remembered was eating pizza before waking up in the morning with grazes on her body, she said.

"Basically, I remember being out for dinner, eating a slice of pizza and I don't remember anything until the morning," she said. "It's extremely hard, not knowing what happened. I mainly just try to block it out."

She woke up in her bed covered in grazes and then went to Christchurch Hospital's Emergency Department after not feeling well and suspecting something sinister had happened.

"When I first arrived they thought I was drunk from the night before," she said.

"At the time I was training with sport and didn't drink or smoke or anything. My mum approached them and said that was not the way it was."

Tests confirmed she had the drugs Zopiclone and Temazepan in her system - the same drugs later found at Hastie's house when police executed a search warrant.

"I was horrified. It's affected me hugely," she said.

"It has made me more aware when I go out and I'm not as trusting of people."

She was ill for days and could not hold down food. She said she was now "a bit anxious" and she would never forgive Hastie for what he did.

She was disgusted with the home-detention sentence.

"Basically, if he wasn't in a wheelchair he would have had 15 months in prison. [The sentence] started at 18 months in prison and it got worked down because of his guilty plea and things, and a hospital report that said it would not be fair to put him in jail."

The court heard how Hastie had no explanation for stupefying the woman but had acknowledged there was some "kissing and cuddling".

Judge Raoul Neave said he believed it was premeditated offending that had been done to "bring about some affectionate conduct between you two, which you feared would not have been welcome in the absence of the drug".

Police figures show that since 2009 there have been three cases of stupefying in Canterbury.

- © Fairfax NZ News