She was administered four doses of the drug on the first day and a final dose on the second day.
The GP left to go overseas after the final dose and left his assistant with the responsibility of monitoring the woman.
At 6am the following morning, the assistant found her dead in the same position she had been since the previous afternoon.
In a decision released today, Mr Hill found the GP had not provided the woman with sufficient information about the risks and side effects of ibogaine.The doctor also failed to obtain the woman's written consent, which was required because of the treatment's experimental nature.
Mr Hill said the monitoring was "regrettably lax" and that the GP failed to keep comprehensive records.
He found the assistant did not monitor the woman adequately and that the clinic did not operate safely.
"For such a complex and intensive treatment, the documented policies and procedures were minimal," said Mr Hill.
"The impression is that it was a sloppy operation with little regard for professional standards."
Iboga New Zealand Limited was found to be responsible for the organisational failings and breached the Code.
The GP, who has stopped practising here, has agreed to undertake further training before resuming practice in New Zealand.
Should he reapply, the commissioner is recommending the Medical Council to review the GP's competence.
The GP and his assistance had both apologised to the woman's family.
