Digital Public Defence: Marlin Comelon Marlin Comelon at Institute of Clinical Medicine will be defending the thesis Opioids in postoperative pain treatment. Studies on analgesic efficacy and reduction of opioid- induced side effects for the degree of PhD (Philosophiae Doctor).

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Photo: Amalie Huth Hovland, UiO

The public defence will be held as a video conference over Zoom.

The defence will follow regular procedure as far as possible, hence it will be open to the public and the audience can ask ex auditorio questions when invited to do so.

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Due to copyright reasons, an electronic copy of the thesis must be ordered from the faculty. In order for the faculty to have time to process the order, it must be received by the faculty no later than 2 days prior to the public defence. Orders received later than 2 days before the defence will not be processed. Inquiries regarding the thesis after the public defence must be addressed to the candidate.

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Adjudication committee

  • First opponent: Professor Ole Mathiesen, University of Copenhagen, Denmark
  • Second opponent: Professor Pål Klepstad, Norwegian University of Science and Technology, Trondheim 
  • Third member and chair of the evaluation committee: Professor Signe Søvik, Institute of Clinical Medicine, University of Oslo

Chair of defence

Professor Emeritus Vegard Dahl, Institute of Clinical Medicine, University of Oslo

Principal supervisor

Harald Lenz


Opioids have an important role in the treatment of postoperative pain, making them essential drugs in the field of anesthesiology. However, opioids have common side effects such as nausea, vomiting, constipation and respiratory depression. Recently there has also been focus on a less known side effect, opioid-induced hyperalgesia, when paradoxical lowering of the pain threshold increases pain after opioid use. 

In her thesis, «Opioids in postoperative pain treatment. Studies on analgesic efficacy and reduction of opioid-induced side effects» Marlin Comelon has conducted three randomized controlled trials on the analgesic effect and side effects of opioids with relevance in the postoperative setting. In the first study, no effect on constipation was found from adding peripherally acting naloxone to the opioid oxycodone after hysterectomy. Naloxone did, however, not antagonize the analgesic effect of oxycodone. The second study focused on tapentadol which combines effects from µ-opioid receptors and noradrenaline reuptake inhibition for analgesia. Similar analgesic effects from tapentadol and oxycodone after hysterectomy were found, but the patients receiving tapentadol had less nausea and need for antiemetics. The third study was an experimental crossover study on healthy volunteers. It demonstrated that gradual withdrawal of remifentanil infusion, as opposed to abrupt withdrawal, could prevent opioid-induced hyperalgesia. 

The two clinical studies in the thesis contribute to the evidence on which patients may have benefits from these drugs over standard treatment. Oxycodone-naloxone is not likely to have effect in patients with normal risk of postoperative constipation but can be an alternative for long-term use in patients with a high risk of constipation. Tapentadol is an option for patients with previous postoperative nausea and vomiting. The study on opioid-induced hyperalgesia helps increase awareness of adverse postoperative effects from perioperative opioids. 

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Published Apr. 14, 2021 9:35 AM - Last modified Apr. 29, 2021 2:37 PM