[The estimation of the i.m. morphine-equivalent in cancer pain treatment with different opioids or different routes of administrations. Practical meaning and limitations.]

What Orthopaedic Surgeons Need to Know: The Basic Science Behind Opioids

On October 26, 2017, US president, Donald J. Trump, declared the opioid epidemic a national public health emergency. This declaration opened the door to government funding for programs geared toward studying and treating opioid addiction; however, part of the responsibility to slow the epidemic falls on physicians. Orthopaedic surgeons prescribed the third-highest number of narcotic prescriptions among all physician groups, and therefore, they have a major role to play in decreasing the use of opioids. Although restricting prescriptions is part of the solution, orthopaedic surgeries are often painful, and opioid medications, along with other multimodal nonopioid medications, allow patients to control pain and improve function, especially in the short term. Therefore, to successfully manage pain and opioid prescriptions, orthopaedic surgeons should know the basic science behind these powerful medications. Understanding the basic mechanism of action of opioid and nonopioid medication classes, knowing what oral morphine equivalent are, and knowing which nonopioid drugs can amplify or weaken the potency of opioids will help orthopaedic surgeons become more informed prescribers and leaders in helping control the opioid epidemic.

[Opioids in "non-malignant" pain-results of long-term treatment in patients with rheumatic disease.]

The oral administration of strong opioids like morphine is a very effective treatment in cancer pain. However, these analgesics are rarely prescribed for patients suffering from severe "non-malignant" pain. We examined the effects of oral opioids (morphine sulphate tablets, buprenorphine and levomethadone) given to patients with intractable rheumatic pain, which were refractory to other therapeutic measures. The origin of pain was inflammation or a degenerative lesion of the spine. Within a period of more than 3 years, 12 patients were treated accordingly. In 9 patients we could achieve sufficient pain relief, two of them showing improvement only after having changed the initially prescribed drug. We had to stop opioid medication in two patients because of side-effects and, moreover, in one patient because of failure to produce analgesia. 775 weeks of treatment were documented until December 31th, 1990, with an individual duration ranging from 11 to 145 weeks. It was necessary to increase the dose of morphine in the course of treatment of one patient, who is up to now being treated for more than 77 weeks. In all other patients the doses were either stable or varied. No severe side-effects such as respiratory depression were associated with long-term opioid therapy. Constipation was observed in 4 patients, nausea in two patients and urinary retention in one patient. These side-effects could be well treated by an additional medication. No drug abuse, dependence or tolerance were observed. Strong opioids are not analgesics of first choice in patients with rheumatic disease, but an opioid medication should be considered-as well as in patients with intractable pain caused by another disease-when alternative therapeutic measures have failed. The principles of opioid medication in rheumatic pain are similar to those in patients with cancer pain.

[Drugs for postoperative analgesia: routine and new aspects: Part 2: opioids, ketamine and gabapentinoids]

In part 1 of this review, perioperative aspects of the use of non-opioids (acetaminophene, dipyrone, traditional NSAR, coxibs) were discussed. In part 2 the perioperative aspects of opioids (weak opioids: tramadol, tilidine with naloxone, strong opioids: morphine, piritramide, oxycodone, hydromorphone, fentanyl, methadone, buprenorphine) and coanalgesics (gabapentinoids; ketamine) will now be presented. The main aim of the review is to describe the use, risks and cost of some substances to facilitate the differential indication. New aspects concerning the use of gabapentinoids and ketamine are discussed.

Clinical pharmacokinetics of transdermal opioids: focus on transdermal fentanyl

Transdermal delivery allows continuous systemic application of opioids through the intact skin. This review analyses the pharmacokinetic properties of transdermal opioid administration in the context of clinical experience, with a focus on fentanyl. A transdermal therapeutic system (TTS) for fentanyl has been developed. The amount of fentanyl released is proportional to the surface area of the TTS, which is available in different sizes. After the first application of a TTS, a fentanyl depot concentrates in the upper skin layers and it takes several hours until clinical effects are observed. The time from application to minimal effective and maximum serum concentrations is 1.2 to 40 hours and 12 to 48 hours, respectively. Steady state is reached on the third day, and can be maintained as long as patches are renewed. Within each 72-hour period, serum concentrations decrease gradually over the second and third days. When a TTS is removed, fentanyl continues to be absorbed into the systemic circulation from the cutaneous depot. The terminal half-life for TTS fentanyl is approximately 13 to 25 hours. The interindividual variability of serum concentrations, partly caused by different clearance rates, is markedly larger than the intraindividual variability. The effectiveness of TTS fentanyl was first demonstrated in acute postoperative pain. However, the slow pharmacokinetics and large variability of TTS fentanyl, together with the relatively short duration of postoperative pain, precluded adequate dose finding and led to inadequate pain relief or, especially, a high incidence of respiratory depression; such use is now contraindicated. Conversely, in cancer pain, TTS fentanyl offers an interesting alternative to oral morphine, and its effectiveness and tolerability in this indication has been demonstrated by a number of trials. Its usefulness in chronic pain of nonmalignant origin remains to be confirmed in controlled trials. In general, TTS fentanyl produces the same adverse effects as other opioids, mainly sedation, nausea, vomiting and constipation. In comparison with oral morphine, TTS fentanyl causes fewer gastrointestinal adverse events. The risk of hypoventilation is comparatively low in cancer patients. Sufentanil and buprenorphine may also be suitable for transdermal delivery, but clinical results are not yet available. Transdermal morphine is only useful if applied to de-epithelialised skin. However, iontophoresis may allow transdermal administration of opioids, including morphine, with a rapid achievement of steady state concentrations and the ability to adjust delivery rates. This would be beneficial for acute and/or breakthrough pain, and initial clinical trials are in progress.

High-dose oral morphine in cancer pain management: a report of twelve cases

We present 12 case reports from patients treated with more than 600 mg of morphine per day. We found no "opioid-nonresponsive pain" under treatment with a combination of morphine and nonopioids, supplemented with coanalgesics where appropriate. Side effects of morphine therapy were controlled with adjuvant drugs. Serious adverse effects were not observed. Episodes of break-through pain, dysphagia, and dyspnea caused by far advanced cancer disease were seen frequently.

Direct conversion from oral morphine to transdermal fentanyl: a multicenter study in patients with cancer pain

Direct conversion from oral morphine to transdermal fentanyl with a ratio of oral morphine/transdermal fentanyl (100:1 mg) daily was examined in patients with cancer pain. Patients with a 'stable and low level of cancer pain' receiving a constant dosage of sustained release morphine during a pre-study phase of 6 days were included in the study. Initial fentanyl dosage was calculated by a conversion table. The transdermal system was changed every 72 h and the dosage was adjusted to the needs of the patients according to the VAS scores and the requirement of liquid morphine, which was allowed to achieve sufficient pain relief. Regression analysis at the end of the study revealed a mean morphine/transdermal fentanyl ratio of 70:1. Pain relief during treatment with transdermal fentanyl was identical to sustained release morphine. However, significantly more patients took supplemental medication with liquid morphine during transdermal fentanyl therapy. The number of patients suffering from pain attacks did not increase with transdermal fentanyl. Constipation and medication with laxatives decreased significantly during fentanyl therapy. Other side effects and vital signs were identical. Three patients suffered from a morphine withdrawal syndrome beginning within the first 24 h of transdermal fentanyl therapy. Cutaneous reactions to the patch were rare, mild and transient. Patients and physicians reported satisfaction with the transdermal therapy. 94.7% of the patients chose to continue the transdermal fentanyl therapy at the end of the study due to better performance in comparison to oral morphine. Due to these results an initial conversion from oral morphine to transdermal fentanyl with the ratio of 100:1 is safe and effective.

[Experience with intra- and perioperative high-dosage steroids in microneursurgical revision operations on lumbar discs.]

A consecutive series of 100 microneurosurgical revision operations on lumbar discs has been evaluated in a prospective and randomized clinical trial analyzing the influence of dexamethasone on postoperative clinical outcome.

METHODS

Of the 100 patients, 50 received dexamethasone 8 mg by local intrathecal injection during the operation and perioperative dexamethasone by a systemic route for 7 days. A reference group of 50 patients did not receive any steroids. The two groups were compared with reference to postoperative lumbar and radicular pain, regression of paresis, analgesic requirements during hospitalization and duration of stay in hospital. One year after the end of the study clinical results and ability to work in the two groups were compared.

RESULTS

A significantly lower analgesic requirement was found in the dexamethasone-treated group. We found no evidence that steroids had ameliorate the regression of paresis or lumbar and radicular pain at the end of hospitalization. There was no difference in the clinical outcome 1 year after reoperation.

CONCLUSIONS

After revision operations on lumbar discs, corticosteroids are a helpful adjuvant drug for relief of lumbar or radicular pain, but they do not significantly improve the final clinical outcome.

Transdermal fentanyl in uncontrolled cancer pain: titration on a day-to-day basis as a procedure for safe and effective dose finding--a pilot study in 20 patients

All communications on the use of transdermal fentanyl as well as the recommendations of the manufacturer include the direction that patients should be titrated with a short-acting narcotic to control their cancer pain before they are converted to a fentanyl transdermal therapeutic system (TTS). We investigated the possibility of avoiding this titration phase by immediate fentanyl TTS therapy in patients with uncontrolled cancer pain. Dose finding was performed by direct titration of fentanyl TTS according to clinical necessity on a day-to-day basis. Morphine solution for rescue medication was available. Short-term follow-up was 28 days, and 20 patients (10 in- and 10 outpatients) were evaluable. On the average, sufficient pain control [visual analogue scale (VAS) < 35 mm] was reached within 48 h of the start of fentanyl TTS. The mean VAS values before and during fentanyl TTS therapy were 53 mm (before), 27 mm (week 1), 21 mm (week 2), 18 mm (week 3) and 21 mm (week 4). There were statistically significant lower VAS values at all follow-up times compared to pretreatment values (e.g. pretreatment to day 1: P = 0.019; pretreatment to day 28: P = 0.002; Wilcoxon sign-rank test). The mean fentanyl TTS doses were 70 micrograms/h (week 1), 98 micrograms/h (week 2), 107 micrograms/h (week 3) and 116 micrograms/h (week 4). The differences of mean fentanyl TTS does were significantly different between days 1 and 7 (P < 0.001) and between days 8 and 14 (P = 0.006), but not between days 15 and 21 and days 22 and 28.(ABSTRACT TRUNCATED AT 250 WORDS)