[Differential therapeutic aspects of analgesia with oral sustained-release strong opioids: application intervals, metabolism and immunosuppression]

The opioid oxycodone use-dependently inhibits the cardiac sodium channel NaV 1.5

BACKGROUND AND PURPOSE

Oxycodone is a potent semi-synthetic opioid that is commonly used for the treatment of severe acute and chronic pain. However, treatment with oxycodone can lead to cardiac electrical changes, such as long QT syndrome, potentially inducing sudden cardiac arrest. Here, we investigate whether the cardiac side effects of oxycodone can be explained by modulation of the cardiac Nav 1.5 sodium channel.

EXPERIMENTAL APPROACH

Heterologously expressed human Nav 1.5, Nav 1.7 (HEK293 cells) or Nav 1.8 channels (mouse N1E-115 cells) were used for whole-cell patch-clamp electrophysiology. A variety of voltage-clamp protocols were used to test the effect of oxycodone on different channel gating modalities. Human stem cell-derived cardiomyocytes were used to measure the effect of oxycodone on cardiomyocyte beating.

KEY RESULTS

Oxycodone inhibited Nav 1.5 channels, concentration and use-dependently, with an IC50 of 483 μM. In addition, oxycodone slows recovery of Nav 1.5 channels from fast inactivation and increases slow inactivation. At high concentrations, these effects lead to a reduced beat rate in cardiomyocytes and to arrhythmia. In contrast, no such effects could be observed on Nav 1.7 or Nav 1.8 channels.

CONCLUSIONS AND IMPLICATIONS

Oxycodone leads to an accumulation of Nav 1.5 channels in inactivated states, with a slow time course. Although the concentrations needed to elicit cardiac arrhythmias in vitro are relatively high, some patients under long-term treatment with oxycodone as well as drug abusers and addicts might suffer from severe cardiac side effects induced by the slowly developing effects of oxycodone on Nav 1.5 channels.

[Oral osmotic hydromorphone (OROS) in patients with chronic severe pain due to osteoarthritis under daily routine conditions]

OBJECTIVE

Objective of this prospective, non-interventional study was to obtain data under a therapy with oral osmotic hydromorphone (OROS) in patients with chronic severe pain due to osteoarthritis under daily routineconditions.

METHOD

Using the Brief Pain Inventory (BPI) patients assessed pain relief as well as the impact of pain on activities of daily living. Pain control, treatment satisfaction (by patient and investigator), physical therapy capability and the WOMAC-Index (Western Ontario and McMaster Universities Osteoarthritis) were additionally evaluated. Adverse events were continuously monitored throughout the study.

RESULTS

206 patients with chronic severe pain due to osteoarthritis and an initial pain intensity of 6 (NRS 0-10) received oral OROS-hydromorphone for three months. Under this treatment pain relief as well as the impact of pain on activities of daily living improved significantly. At the last examination, the patients reported a mean pain reduction of 2.5 (rest)/3.0 (movement) by day and of 2.6 (rest)/3.1 (movement) bynight (p < 0.0001). The very good pain control was accompanied by a high treatment satisfaction and an improved sleep quality. Physical therapy capability improved in 77.9% of the patients, the WOMAC index as indicator of pain and function in osteoarthritis decreased significantly from 13.3 (baseline) to 7.5 (V6). The most frequently reported adverse events were obstipation, nausea, dizziness and fatigue. 17.5% of the patients cut the study short because of adverse events.

CONCLUSION

The treatment of patients with chronic pain due to osteoarthritis with oral osmotic hydromorphone resulted in a significant reduction of all documented pain related assessments.