Relative potency of controlled-release oxycodone and controlled-release morphine in a postoperative pain model

A new cocktail formula with diprospan of local infiltration analgesia in primary total hip arthroplasty: A prospective, randomized, controlled, observer-blinded study

OBJECTIVE

This study aimed to observe the analgesic effect of the cocktail formulation with diprospan during total hip arthroplasty (THA).

METHODS

From September 2018 to April 2019, 120 patients undergoing primary unilateral THA were included in this prospective, randomized, observer-blinded study. Patients were randomized into three groups, according to the different local infiltration analgesia (LIA) strategies: LIA with ropivacaine (the ropivacaine group, n = 40), LIA with a new cocktail containing ropivacaine, diprospan, and morphine (the cocktail group, n = 40), and the control group (n = 40). The primary outcomes included postoperative pain scores. The resting visual analogue scale (VAS) scores were measured at 2, 6, and 12 h after the surgery (a.m. and p.m.) on postoperative day (POD) 1, POD2, and the day of discharge. Movement VAS scores were assessed at 6 h, 12 h after the operation (a.m. and p.m.) on POD1, POD2, and the day of discharge. The secondary outcomes included opioid consumption, postoperative hospital stay, range of motion of the hip at discharge, patient satisfaction, and the results of the follow-up.

RESULTS

After the screening, 120 patients were randomized into three groups (40 patients in each group). All of the patients completed the trial. The resting VAS scores in the ropivacaine group and cocktail group at 2 h were lower than those in the control group (P < 0.001 and P < 0.001, respectively, F = 17.054), and the same trend was also postoperatively found at 6 h (p = 0.005 and P = 0.002, F = 6.212). Twelve hours after the operation, the pain score in the cocktail group was lower than that in the other two groups, but only the difference between the cocktail group and the control group was statistically significant (P = 0.018, F = 3.144). From the morning of the first postoperative day to the a.m. on POD 2, the VAS scores in the cocktail group were significantly lower than those in the ropivacaine group and the control group. Furthermore, the movement VAS scores in the ropivacaine group and the cocktail group were better than those in the control group at 6 and 12 h post-operation (P < 0.05). The per capita opioid consumption in the cocktail group was less than that in the ropivacaine group and the control group within 24 h post-operation. There were no significant differences in the comparison of additional indicators among the three groups.

CONCLUSION

The new cocktail with diprospan had a better result and longer duration time for early postoperative pain control in primary THA via the posterolateral approach under general anesthesia, especially for treating resting pain.

Analgesic effects of indomethacin spray on drug-induced oral mucositis pain in patients with cancer: A single-arm cross-sectional study

Aims

Symptomatic treatment is insufficient for chemotherapy‐ or targeted therapy‐induced oral mucositis (OM) pain, and benzydamine mouthwash is not commercially available in Japan. We evaluated the analgesic effects of an in‐hospital preparation of 0.25% indomethacin spray (IMS) on anticancer drug‐induced OM pain.

Methods

This single‐arm prospective trial enrolled 20 patients (median age 62.0 years) with OM and numerical rating scale scores of ≥5 who were undergoing chemotherapy or targeted therapy in our hospital. Pain scores were recorded using a visual analog scale (VAS) before and 30 min after IMS administration. Pain relief (PR) scores were recorded at 15, 30, and 60 min after IMS administration; total PR after 60 min (TOTPAR₆₀) was calculated, and the mean PR score after 3 days (PR_3days) was determined.

Results

The median (interquartile range) OM grade of the participants was 2.0 (2.0–2.3). The VAS score decreased significantly at 30 min after IMS administration (p = .001). The median (interquartile range) TOTPAR₆₀ and PR_3days were 6.0 (3.8–7.3) and 2.0 (2.0–3.0), respectively.

Conclusions

IMS helped improve patients’ quality of life. The risk of systemic adverse effects was low because of the low dose administered. IMS effectively relieved anticancer drug‐induced OM pain and may be useful for immediate self‐medication.

Analgesic effect of single-shot ropivacaine at different layers of the surgical site in primary total hip arthroplasty: a randomised, controlled, observer-blinded study

Objectives

The aim of this study was to evaluate the efficacy of local infiltration anaesthesia (LIA) during primary total hip arthroplasty (THA) via a posterolateral approach under general anaesthesia and to compare the efficacy of LIA in all layers with LIA in the deep and superficial fascia.

Patients and methods

One hundred twenty patients were randomised into three groups: LIA in the deep and superficial fascia (group A), LIA in all layers (group B) and the control (group C). The primary outcomes were the visual analogue scale (VAS) pain scores at rest and on movement within 72 h (h) postoperatively. The secondary outcomes included opioid consumption, patient satisfaction, range of motion (ROM), straight leg raise completion rate, length of hospital stay, opioid-related side effects and wound complications. We followed the patients until 6 months after discharge.

Results

At 2 and 6 h, groups A and B had lower resting VAS scores than group C (p < 0.01); at 12 h, group B had a lower resting VAS score than group C (p < 0.05). At 6 and 12 h, the movement VAS scores in groups A and B were lower than those in group C (p < 0.01). Groups A and B had similar VAS scores during the observation period. Groups A and B had higher levels of patient satisfaction than group C (p = 0.03 and p = 0.018, respectively). Opioid consumption was similar in the three groups. There were no significant differences in the other secondary outcomes amongst the three groups. No difference was found in hip rehabilitation or chronic pain during the follow-up period.

Conclusion

Single-shot LIA with ropivacaine alone reduces the pain score during the first 12 postoperative hours and improves patients’ satisfaction with THA. LIA in the deep and superficial fascia and LIA in all layers have similar analgesic effects. LIA in the deep and superficial fascia may be an alternative method to LIA in all layers.

Are newer, more expensive pharmacotherapy options associated with superior symptom control compared to less costly agents used in a collaborative practice setting?

Innovative approaches to care may be necessary to provide the most effective symptom management to hospice patients. One approach is prescribing newer pharmacotherapy options with the potential to improve symptom management in hospice. Such therapies are sometimes prescribed outside of Food and Drug Administration indications and are typically more costly than older agents usedfor the same symptoms. Another approach is the collaborative practice (CP) care model, whereby clinical pharmacists are given prescriptive authority according to evidence-based protocols and algorithms within boundaries approved by a physician. The agents typically included in CPprotocols are those with wide therapeutic indices and with substantial evidence to support their use. The purpose of this study was to examine both approaches to management ofpain, insomnia, and nausea, comparing symptom scores for those patients who received noncollaborative drug therapies (transdermal fentanyl, zolpidem, and ondansetron) to those who received agents under CP (oral sustained-release opioids, temazepam, andprochlorperazine). The object of the study was to investigate outcomes associated with newer drug therapy options as compared to older agents for the management of pain, insomnia, and nausea. A secondary goal is to compare symptom outcomes for patients receiving pharmaceutical care under CP and non-CP models. The study design was retrospective with a cohort. A total of 50 patients were randomly selected for each cohort of the pain and insomnia study arms. Only 45 patients prescribed oral ondansetron met inclusion criteriafor the nausea group; 45 patients prescribed prochlorperazine were randomly selected as the comparator group. Patients were compared on their degree of response to the prescribed therapy. Response was classified as complete, partial, no improvement from baseline, worsened, or unknown. A complete response was defined as the symptom score improving to a 0 of 10, regardless of the previous value documented. A partial response was defined as any improvement in score that did not result in a 0 of 10. No improvement from baseline reflected a lack of overall change in score throughout the series of data points collected. A worsened response was any score found to be higher than the score documented at the time of dispense. The unknown category reflects any set of scores that had an “NIA” documented at the time of medication dispense or when documented for both attempts subsequent to dispensing the medication. A complete response was present in 14 of 50 (24 percent) of the patients prescribed fentanyl as compared with 12 of 50 (28 percent) of those prescribed oral therapy (p = .82). Responses defined as partial, no improvement over baseline, worsened, and unknown were also comparable between the two cohorts. A complete response was seen in 26 patients prescribed temazepam (52 percent), whereas only 11 (22 percent) of patients initially prescribed zolpidem achieved the same response (p = .003 7). Both groups had a similar distribution of partial, no improvement over baseline, and worsened responses. For the nausea arm of the study, a difference was found in the number of complete responses, favoring prochlorperazine (22 of 45, 48.9 percent for prochlorperazine, 12 of 45, 26.7 percent for ondansetron, p =. 0504), as well as an increased number of worse responses seen with ondansetron patients (p = .0513); however, neither difference was statistically significant. Newer pharmacotherapy options for the management of pain, insomnia, and nausea were not found to be superior when compared to older agents prescribed under CR

In vitro metabolism of specific CYP2D and CYP3A opioid substrates using rat liver S9 fractions and mass spectrometry reveal a severe metabolic impairment with increasing age

Codeine and oxycodone are opioids used to alleviate pain. The outcome of the treatment is ultimately related to their metabolism by Cytochromes P450 (CYPs). Depending on the drugs used, alterations in the metabolism of drugs by CYPs can lead to severe consequences including alterations in their efficacy, safety and toxicity. The objectives of this study were to develop a novel HPLC-MS/MS method capable of quantifying codeine and oxycodone along with specific metabolites using an isotopic dilution strategy and study the rate of formation of morphine (CYP2D), norcodeine (CYP3A), oxymorphone (CYP2D) and noroxycodone (CYP3A). The chromatographic separation was achieved using a Biobasic C₁₈ 100 × 1 mm column combined with an isocratic mobile phase composed of methanol and 10 mm ammonium acetate (40:60) at a flow rate of 75 μL/min. The mass spectrometer was operating in scan mode MS/MS and the analytical range was set at 10-10 000 nm. The precision (RSD) and accuracy (RE) observed were 4.4-11.5 and -9.1-6.1% respectively. Liver S9 fractions from 3-, 6-, 12- and 18-month-old male Sprague-Dawley rats were prepared and Michaelis-Menten parameters were determined. The derived maximum enzyme velocity suggested a rapid saturation of the CYP2D and CYP3A active sites in the liver S9 fractions of 18-month-old rats. Moreover, metabolic stabilities of codeine and oxycodone in rat liver S9 fractions were significantly greater for the 18-month-old rats. This study suggests that there is an impairment of CYP2D and CYP3A metabolism in aging rats.

Design and in vivo evaluation of oxycodone once-a-day controlled-release tablets

The aim of present study was to design oxycodone once-a-day controlled-release (CR) tablets and to perform in vitro/in vivo characterizations. Release profiles to achieve desired plasma concentration versus time curves were established by using simulation software and reported pharmacokinetic parameters of the drug. Hydroxypropyl methylcellulose (HPMC) 100,000 mPa·s was used as a release modifier because the polymer was found to be resistant to changes in conditions of the release study, including rotation speed of paddle and ion strength. The burst release of the drug from the CR tablets could be suppressed by applying an additional HPMC layer as a physical barrier. Finally, the oxycodone once-a-day tablet was comprised of two layers, an inert HPMC layer and a CR layer containing drug and HPMC. Commercial products, either 10 mg bis in die (bid [twice a day]) or once-a-day CR tablets (20 mg) were administered to healthy volunteers, and calculated pharmacokinetic parameters indicated bioequivalence of the two different treatments. The findings of the present study emphasize the potential of oxycodone once-a-day CR tablets for improved patient compliance, safety, and efficacy, which could help researchers to develop new CR dosage forms of oxycodone.

Molecular mechanisms underlying the enhanced analgesic effect of oxycodone compared to morphine in chemotherapy-induced neuropathic pain

Oxycodone is a μ-opioid receptor agonist, used for the treatment of a large variety of painful disorders. Several studies have reported that oxycodone is a more potent pain reliever than morphine, and that it improves the quality of life of patients. However, the neurobiological mechanisms underlying the therapeutic action of these two opioids are only partially understood. The aim of this study was to define the molecular changes underlying the long-lasting analgesic effects of oxycodone and morphine in an animal model of peripheral neuropathy induced by a chemotherapic agent, vincristine. Using a behavioural approach, we show that oxycodone maintains an optimal analgesic effect after chronic treatment, whereas the effect of morphine dies down. In addition, using DNA microarray technology on dorsal root ganglia, we provide evidence that the long-term analgesic effect of oxycodone is due to an up-regulation in GABA_B receptor expression in sensory neurons. These receptors are transported to their central terminals within the dorsal horn, and subsequently reinforce a presynaptic inhibition, since only the long-lasting (and not acute) anti-hyperalgesic effect of oxycodone was abolished by intrathecal administration of a GABA_B receptor antagonist; in contrast, the morphine effect was unaffected. Our study demonstrates that the GABA_B receptor is functionally required for the alleviating effect of oxycodone in neuropathic pain condition, thus providing new insight into the molecular mechanisms underlying the sustained analgesic action of oxycodone.

Oxycodone overdose causes naloxone responsive coma and QT prolongation

BACKGROUND

Although there are limited data on oxycodone overdose, it has been suggested that, in addition to central nervous system (CNS) depression, oxycodone may cause QT prolongation. Given the high prescription rate and increasing use of oxycodone, an understanding of its effects and treatment in overdose is necessary.

AIM

To investigate the clinical features, electrocardiogram (ECG) parameters and treatment of oxycodone overdose.

DESIGN

Retrospective review of a clinical database.

METHODS

One hundred and thirty-seven oxycodone overdoses were identified from admissions to a toxicology unit between January 2001 and May 2011. Demographic information, details of ingestion, clinical effects, ECG parameters [heart rate (HR), QT and QRS], naloxone use and length of stay (LOS) were extracted from a clinical database. QT was measured manually and plotted on a QT nomogram. LOS was extracted for all overdoses over the same period.

RESULTS

From 137 oxycodone overdoses, 79 (58%) ingested immediate release (IR) and 58 (42%) ingested sustained release (SR) or a combination of IR and SR. The median age was 40 years [interquartile range (IQR): 33-49 years], and 87 were female (64%). The median ingested dose of IR oxycodone was 70 mg (IQR: 40-100, range: 5-200), compared to 240 mg (IQR: 80-530, range: 30-1600) for SR oxycodone. Benzodiazepines were the most frequent co-ingested drug in 52 (38%) cases. No arrhythmias were recorded. Twenty-four patients (18%) had bradycardia of which five had a HR < 50 beats/min. From 116 available ECGs, the median QRS was 95 ms (IQR: 90-102 ms), and there were 20 (17%) abnormal QT-HR pairs. Naloxone boluses were required in 65 admissions (47%), and 34 (25%) required a naloxone infusion. There was higher overall naloxone use with SR and IR + SR (32/58, 55%) compared to IR oxycodone (33/79, 42%). The median LOS was 18 h (IQR: 12-35), which was greater than the median LOS for all toxicology admissions at 15 h (IQR: 8-24) over the same period. Patients requiring a naloxone infusion had an even greater LOS of 36 h (IQR: 20-62 h).

CONCLUSION

In addition to the expected CNS depression, the opioid oxycodone can cause bradycardia and QT prolongation in overdose. The SR formulation is associated with the use of naloxone infusions and a longer LOS.

Controlled-release oxycodone tablets after transdermal-based opioid therapy in patients with cancer and non-cancer pain

BACKGROUND AND AIMS

Several publications and guidelines stress the efficacy and safety of opioid-based therapy for cancer and non-cancer pain management. The first point of the World Health Organization (WHO) guidelines recommends that, if possible, analgesics should be given by mouth. This advice fully matches the European Society for Medical Oncology (ESMO) guidelines, which advise that opioids should be titrated to take effect as rapidly as possible. The European Association for Palliative Care (EAPC) guidelines specify that transdermal fentanyl should be administered only in patients with stable analgesic requirements. The aim of this study was to assess the efficacy and influence on the quality of life of controlled- release (CR) oxycodone in patients who had obtained no or only partial pain relief after transdermal (TTD)-based opioid therapy.

METHODS

Forty-one consecutive patients experiencing persistent cancer and non-cancer related pain and in treatment with transdermal- based opioid therapy for at least 5 days were enrolled in this open-label, multicenter observational study. All patients were switched from transdermal to oral opioid therapy with oxycodone CR for 21 days. Pain intensity was rated on a numeric rating scale (NRS) from 0 to 10 (0=no pain, 10=maximum severity). Patients were asked to rate their perceptions on efficacy and pain interference on the quality of life on an NRS from 0 to 10 (0=no interference, 10=maximum interference).

RESULTS

After 3 days with oxycodone CR, pain intensity decreased by 38.83% (p<0.001) and maintained a significant decrease throughout the period (T0-T7: -59.71%, p<0.001; T0-T21: -65.75%, p<0.001). The average daily dose of oxycodone CR increased from 68.75 mg at baseline to 72.39 mg after 7 days and was maintained stable until the study ended. At T0, 56.10% of patients suffered from severe pain (NRS 7- 10); this percentage had decreased to 2.56% at the end of the study. About 7% of patients considered transdermal therapy effective at baseline; after 21 days, 72.22% and 19.44% of patients considered it effective and very effective, respectively. Quality of life improved significantly during the 21 days with the oral treatment (p<0.001).

CONCLUSIONS

Switching from transdermal opioid to oxycodone CR treatment is effective and leads to patients' improved satisfaction and quality of life.

Advantage of early induction of opioid to control pain induced by irradiation in head and neck cancer patients

OBJECTIVE

Although radiotherapy is effective for head and neck cancer patients, the local pain evoked by the irradiation itself reduces food intake and frequently halts the treatment. Thus, pain control is an important problem in radiotherapy for head and neck cancer. We performed to examine whether early induction of low-dose, opioid from mild pain improves dietary and caloric intake, while reducing weight loss.

METHODS

The subjects were 43 patients who were hospitalized for head and neck cancer from 2004 to 2008. They were patients who underwent radiation treatment but those who did not undergo preoperative treatment. They were divided into two groups, depending on whether the pain was mild or moderate when an opioid was introduced (MILD and MODERATE, N=23 and 20, respectively).

RESULTS

The visual analog scale scores for pain were significantly lower in the MILD than in the MODERATE group at between 25 and 50 Gy. The amount of oxycodone used for pain was significantly lower in the MILD than the MODERATE group. A regular diet was maintained for significantly longer in the MILD group. Caloric intake was significantly higher in the MILD group at over 20 Gy. Weight loss was significantly lower in the MILD group at over 20 Gy. The incidence of side effects was equal in both groups.

CONCLUSION

Our results indicated that the introduction of opioids for mild pain during radiotherapy controls the level of pain, improving food intake in head and neck cancer patients.

Different effects of morphine and oxycodone in experimentally evoked hyperalgesia: a human translational study

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT * Previous studies using short-lasting experimental pain stimulations in healthy volunteers have shown differences in opioid effects regarding visceral pain stimulations. However, these differences can be more pronounced in patients due to a sensitized pain system. Therefore, the aim of the present study was to mimic the clinical situation by investigating opioid effects on experimental pain in healthy volunteers after experimentally evoked hyperalgesia. WHAT THIS STUDY ADDS? * We now know that morphine and oxycodone exerts different effects in the sensitized pain system as we found a greater analgesic effect of oxycodone in response to skin, muscle and oesophageal pain stimulation. This supports clinicians' experiences that oxycodone can be superior to morphine in the treatment of some pain conditions. The evoked hyperalgesia bridged findings from studies in healthy volunteers to patients, and new fundamental knowledge on different analgesic effects in hyperalgesia was found. AIM Similar analgesics may have different analgesic potencies especially in patients in whom the pain system is sensitized. The aim was to investigate different opioid effects on experimental pain after the sensitized pain system was mimicked evoking hyperalgesia in healthy volunteers. METHODS Twenty-four healthy volunteers were randomized to treatment with morphine (30 mg orally) and oxycodone (15 mg orally) or placebo in a double-blind crossover study. Hyperalgesia was induced by oesophageal perfusion with acid and capsaicin. Several exploratory endpoints were studied using skin heat, muscle pressure and oesophageal mechanical, heat and electrical stimulation. Effects on pain from deeper structures were considered most important. RESULTS Different analgesic potencies were found. Oxycodone had a greater analgesic effect than morphine attenuating pain from: (i) heat stimulation of skin (P= 0.016); difference between the means of 0.39 degrees C, 95% CI 0.22, 2.09. (ii) muscle pressure (P < 0.001); difference between the means of 11.93kPa, 95% CI 5.4, 18.5. (iii) oesophageal heat stimulation (P < 0.001); difference between the means of 38.54 cm(2), 95% CI 15.37, 61.71 and (iv) oesophageal electrical stimulation (P= 0.016); difference between the means of 6.69mA, 95% CI 1.23, 12.13. CONCLUSION After sensitization of the pain system different analgesic potencies of morphine and oxycodone were found in response to skin, muscle and oesophageal pain stimulation, in which oxycodone had a greater effect. As similar differential analgesic potencies of the two opioids have been found in patients with chronic pain, the experimental hyperalgesia model bridged findings from studies in healthy volunteers to patients.

Effect of the inhibition of CYP3A4 or CYP2D6 on the pharmacokinetics and pharmacodynamics of oxycodone

PURPOSE

The main metabolic pathways of oxycodone, a potent opioid analgetic, are N-demethylation (CYP3A4) to inactive noroxycodone and O-demethylation (CYP2D6) to active oxymorphone. We performed a three-way, placebo-controlled, double-blind cross-over study to assess the pharmacokinetic and pharmacodynamic consequences of drug interactions with oxycodone.

METHODS

The 12 participants (CYP2D6 extensive metabolizers) were pre-treated with placebo, ketoconazole or paroxetine before oral oxycodone ingestion (0.2 mg/kg).

RESULTS

Pre-treatment with ketoconazole increased the AUC for oxycodone 2- to 3-fold compared with placebo or paroxetine. In combination with placebo, oxycodone induced the expected decrease in pupil diameter. This decrease was accentuated in the presence of ketoconazole, but blunted by paroxetine. In comparison to pre-treatment with placebo, ketoconazole increased nausea, drowsiness, and pruritus associated with oxycodone. In contrast, the effect of pre-treatment with paroxetine on the above-mentioned adverse events was not different from that of placebo. Ketoconazole increased the analgetic effect of oxycodone, whereas paroxetine was not different from placebo.

CONCLUSIONS

Inhibition of CYP3A4 by ketoconazole increases the exposure and some pharmacodynamic effects of oxycodone. Paroxetine pretreatment inhibits CYP2D6 without inducing relevant changes in oxycodone exposure, and partially blunts the pharmacodynamic effects of oxycodone due to intrinsic pharmacological activities. Pharmacodynamic changes associated with CYP3A4 inhibition may be clinically important in patients treated with oxycodone.

Significance of protein binding in pharmacokinetics and pharmacodynamics

The significance of plasma protein binding on drug efficacy and, subsequently, the clinical relevance of changes in protein binding has been controversially discussed for decades. The uncertainty concerning the impact of plasma protein binding on a drug's pharmacological activity is, in part, related to the approach used when investigating and interpreting protein binding effects in vitro and in vivo. Frequently, a generalized one-size-fits-all approach, such as "protein binding does matter/does not matter," may not be applicable. An appropriate analysis requires careful consideration of both pharmacokinetic and pharmacodynamic processes, as they both contribute to the safety and efficacy of drugs. Therefore, the aim of this article is to provide a concise review of the theoretical concepts of protein binding, and to discuss relevant examples where applicable.

Does co-administration of paroxetine change oxycodone analgesia: An interaction study in chronic pain patients

Oxycodone is a strong opioid and it is increasingly used in the management of acute and chronic pain. The pharmacodynamic effects of oxycodone are mainly mediated by the μ-opioid receptor. However, its affinity for the μ-opioid receptor is significantly lower compared with that of morphine and it has been suggested that active metabolites may play a role in oxycodone analgesia. Oxycodone is mainly metabolized by hepatic cytochrome (CYP) enzymes 2D6 and 3A4. Oxycodone is metabolized to oxymorphone, a potent μ-opioid receptor agonist by CYP2D6. However, CYP3A4 is quantitatively a more important metabolic pathway. Chronic pain patients often use multiple medications. Therefore it is important to understand how blocking or inducing these metabolic pathways may affect oxycodone induced analgesia. The aim of this study was to find out whether blocking CYP2D6 would decrease oxycodone induced analgesia in chronic pain patients.

The effects of the antidepressant paroxetine, a potent inhibitor of CYP2D6, on the analgesic effects and pharmacokinetics of oral oxycodone were studied in 20 chronic pain patients using a randomized, double-blind, placebo-controlled cross-over study design. Pain intensity and rescue analgesics were recorded daily, and the pharmacokinetics and pharmacodynamics of oxycodone were studied on the 7th day of concomitant paroxetine (20 mg/day) or placebo administration. The patients were genotyped for CYP2D6, 3A4, 3A5 and ABCB1.

Paroxetine had significant effects on the metabolism of oxycodone but it had no statistically significant effect on oxycodone analgesia or use of morphine for rescue analgesia. Paroxetine increased the dose-adjusted mean AUC0–12h of oxycodone by 19% (−23 to 113%; P = 0.003), and that of noroxycodone by 100% (5–280%; P < 0.0001) but decreased the AUC0–12 h of oxymorphone by 67% (−100 to −22%; P < 0.0001) and that of noroxymorphone by 68% (−100 to −16%; P < 0.0001).

Adverse effects were also recorded in a pain diary for both 7-day periods (placebo/paroxetine). The most common adverse effects were drowsiness and nausea/vomiting. One patient out of four reported dizziness and headache during paroxetine co-administration, whereas no patient reported these during placebo administration (P = 0.0471) indicating that these adverse effects were due to paroxetine.

No statistically significant associations of the CYP2D6 or CYP3A4/5 genotype of the patients and the pharmacokinetics of oxycodone or its metabolites, extent of paroxetine–oxycodone interaction, or analgesic effects were observed probably due to the limited number of patients studied.

The results of this study strongly suggest that CYP2D6 inhibition does not significantly change oxycodone analgesia in chronic pain patients and that the analgesic activity of oxycodone is mainly due to the parent compound and that metabolites, e.g. oxymorphone, play an insignificant role. The clinical implication of these results is that induction of the metabolism of oxycodone may lead to inadequate analgesia while increased drug effects can be expected after addition of potent CYP3A4/5 inhibitors particularly if combined with CYP2D6 inhibitors or when administered to poor metabolizers of CYP2D6.

Opioid rotation: the science and the limitations of the equianalgesic dose table

Opioid rotation refers to a switch from one opioid to another in an effort to improve the response to analgesic therapy or reduce adverse effects. It is a common method to address the problem of poor opioid responsiveness despite optimal dose titration. Guidelines for opioid rotation are empirical and begin with the selection of a safe and reasonably effective starting dose for the new opioid, followed by dose adjustment to optimize the balance between analgesia and side effects. The selection of a starting dose must be based on an estimate of the relative potency between the existing opioid and the new one. Potency, which is defined as the dose required to produce a given effect, differs widely among opioids, and among individuals under varying conditions. To effectively rotate from one opioid to another, the new opioid must be started at a dose that will cause neither toxicity nor abstinence, and will be sufficiently efficacious in that pain is no worse than before the change. The estimate of relative potency used in calculating this starting dose has been codified on "equianalgesic dose tables," which historically have been based on the best science available and have been used with little modification for more than 40 years. These tables, and the clinical protocols used to apply them to opioid rotation, may need revision, however, as the science underlying relative potency evolves. Review of these issues informs the use of opioid rotation in the clinical setting and defines key areas for future research.

Oral oxycodone hydrochloride versus epidural anaesthesia for pain control after radical retropubic prostatectomy

OBJECTIVE

To evaluate whether combined oral intake of paracetamol (4 x 1 g) + oxycodone hydrochloride (2x10 mg) is adequate and equivalent to epidural anaesthesia (EDA) with respect to postoperative pain control and postoperative mobilization after radical retropubic prostatectomy (RRP).

MATERIAL AND METHODS

Forty consecutive patients scheduled for RRP were randomized to either: EDA with ropivacaine + paracetamol (4 x 1 g tablet) + injected or oral morphine on demand (EDA group); or infiltration of 25-40 ml of 0.25% bupivacaine into the wound + oxycodone hydrochloride (2 x 10 mg tablet) + paracetamol (4x1 g tablet) + injected or oral morphine on demand (OXY group). The groups were compared with respect to pain control determined by means of a visual analogue scale (VAS), time to free mobilization, hospital stay, complications, operation time and bleeding.

RESULTS

Both analgesic regimens provided satisfactory analgesia, i.e. VAS scores remained significantly below 4 (p<0.0001). The EDA group experienced slightly less pain than the OXY group on the operation day but this was not significant: median VAS scores of 0.7 and 1.8, respectively (p=0.27). Median VAS scores during hospital stay were 1.7 in both treatment groups. VAS scores ranged from 0.1 to 3.3 and from 0.2 to 3.5 in the EDA and OXY groups, respectively. There was no significant difference in postoperative mobilization between the groups (p=0.06). The median duration of hospital stay was 3 nights in both groups.

CONCLUSION

Postoperative pain control after RRP with oral oxycodone hydrochloride, paracetamol and extra morphine on demand is preferable to EDA when pain control as well as mobilization and costs are taken into account.

Correlates of extramedical use of OxyContin versus other analgesic opioids among the US general population

BACKGROUND

There has been substantial public and media attention regarding extramedical use of OxyContin, but few studies focus on the characteristics of extramedical OxyContin users and whether they differ from extramedical other opioid users.

METHODS

We used data from 8218 respondents who were past-year extramedical opioid analgesic users in the 2005 and 2006 National Survey of Drug Use and Health (NSDUH). We investigated differences in socio-demographic and psychiatric characteristics associated with past-year extramedical OxyContin use (n=1144) versus extramedical other opioid analgesics use (n=7074). Data on opioid sources was compared among past-month users. We also compared extramedical opioid users (n=8218) versus other drug users (n=16,214), and individuals with an analgesic disorder who had past-year extramedical OxyContin use (n=339) versus those with other opioid use (n=820).

RESULTS

Past-year opioid users were more likely than users of other illegal drugs to be more educated and have a past-year major depressive episode. Past-year OxyContin users were more likely than other opioid users to be 18-25 years old (aOR=1.9[1.1,3.2]), and have mental health and deviant behavior problems. Those with past-year analgesic disorder who used OxyContin were more likely to be younger, sell illegal drugs (aOR=2.5[1.5,4.2]), and use illegal drugs than those who used other opioids. Past-month OxyContin users were more likely than past-month other opioid users to buy analgesics from drug dealers/other strangers and obtain opioid analgesics from multiple sources.

CONCLUSION

Our findings point out differences between OxyContin and other opioid users that might help prevention specialists and assist efforts to curb opioid analgesics diversion.

Cancer pain and analgesia

Pain ranges in prevalence from 14-100% among cancer patients and occurs in 50-70% of those in active treatment. Cancer pain may result from direct invasion of tumor into nerves, bones, soft tissue, ligaments, and fascia, and may induce visceral pain through distension and obstruction. Cancer pain is multifaceted. Clinicians may describe cancer pain as acute, chronic, nociceptive (somatic), visceral, or neuropathic. Despite implementation of the WHO guidelines, reports of undertreatment of cancer pain persist in various clinical settings and in spite of decades of work to reduce unnecessary discomfort. Substantial obstacles to adequate pain relief with opioids include specific concerns of patients themselves, their family members, physicians, nurses, and the healthcare system. The WHO analgesic ladder serves as the mainstay of treatment for the relief of cancer pain in concert with tumoricidal, surgical, interventional, radiotherapeutic, psychological, and rehabilitative modalities. This multidimensional approach offers the greatest potential for maximizing analgesia and minimizing adverse effects. Primary therapies are directed at the source of the cancer pain and may enhance a patient's function, longevity, and comfort. Adjuvant therapies include nonopioids that confer analgesic effects in certain medical conditions but primarily treat conditions that do not involve pain. Nonopioid medications (over-the-counter agents) are useful in the management of mild to moderate pain, and their continuation through step 3 of the WHO ladder is an option after weighing a drug's risks and benefits in individual patients. Symptomatic treatment of severe cancer pain should begin with an opioid, regardless of the mechanism of the pain. They are very effective analgesics, titrate easily, and offer a favorable risk/benefit ratio. Cancer pain remains inadequately controlled despite the diagnostic and therapeutic means of ensuring that patients feel comfortable during their illness. Therefore, all practitioners need to make control of cancer pain a professional duty, even if they can only use the most basic and least expensive analgesic medications, such as morphine, codeine, and acetaminophen, to reduce human suffering.

Oxycodone: a review of its use in the management of pain

BACKGROUND

Oxycodone is a strong opioid that acts at mu- and kappa-opioid receptors. It has pharmacological actions similar to strong opioids, but with a specific pharmacologic profile and greater analgesic potency to morphine. The efficacy of oxycodone in managing neuropathic and somatic pain, both of malignant and non-malignant origin, has been established in a wide range of settings.

SCOPE

This review aims to provide a comprehensive evaluation of oxycodone and its role within clinical settings in order to provide an evidence-based perspective on its use in the clinic. Literature searches using Medline, EMBASE and Cochrane Databases were used to compile data for review. The review provides information on the pharmacokinetics and pharmacodynamics of oxycodone and also profiles established clinical data in neuropathic and somatic pain as well as emerging data to support the use of oxycodone in visceral pain, which may be due to its interaction with kappa-opioid receptors. Oxycodone is available in a range of formulations for oral, intraspinal and parenteral administration.

FINDINGS

The prolonged-release form of oxycodone offers a fast onset of analgesia, controlling pain for 12 hours and providing clinically meaningful relief of moderate to severe pain and improving quality of life across a broad spectrum of pain types.

CONCLUSIONS

Oxycodone provides significant pain relief. It has relevant points of difference from other opioids and as such may be a suitable alternative to morphine.

Within-subject comparison of the psychopharmacological profiles of oral oxycodone and oral morphine in non-drug-abusing volunteers

RATIONALE

Nonmedical use and abuse of prescription opioids is a significant problem in the USA. Little attention has been paid to assessing the relative psychopharmacological profile (including abuse liability-related effects) of specific prescription opioids.

OBJECTIVES

The aim of this study is to directly compare the psychopharmacological profile of two oral opioids within the same subject.

METHODS

A randomized, placebo-controlled, crossover study was done in which 20 non-drug-abusing volunteers ingested 10 and 20 mg of oxycodone, 30 and 60 mg of morphine, and placebo in separate sessions. Drug doses were equated on an objective measure of opiate effects: miosis. Subjective, psychomotor, reinforcing, and physiological effects of the opioids were assessed.

RESULTS

In general, the two opioids at equimiotic doses produced similar prototypic opiate-like effects and psychomotor impairment of similar magnitude. However, several effects were found only with 20 mg oxycodone. Both drugs produced abuse liability-related subjective effects but also dysphoric effects, particularly with 60 mg morphine. Neither drug at either dose functioned as a reinforcer, as measured by the Multiple Choice Procedure. Relative potency ratios indicated an average oxycodone/morphine [corrected] ratio of 1:3 [corrected]

CONCLUSIONS

The psychopharmacological profile of oxycodone and morphine at equimiotic doses had many similarities; however, differences were found in producing abuse liability-related and dysphoric effects. In the medical community, it is commonly accepted that oral oxycodone is 1.5 to 2 times as potent as oral morphine in producing analgesia; using this ratio, although patients may experience similar degrees of pain relief, those receiving oxycodone may be experiencing stronger and potentially different psychopharmacological effects.

Postoperative pain management: new, convenient analgesic therapies

Despite the potential benefits to patient health that can result from effective pain management, survey results continue to indicate that acute postoperative pain remains inadequately managed worldwide. The development of novel analgesics and advanced analgesic delivery techniques has the potential to improve current strategies for postoperative pain management. This article outlines the pharmacological principles and clinical utility of recently developed agents and a novel drug delivery device indicated for the management of moderate-to-severe acute postoperative pain.

Premedication with controlled-release oxycodone does not improve management of postoperative pain after day-case gynaecological laparoscopic surgery

BACKGROUND

Controlled-release (CR) oxycodone provides an option for the prevention of postoperative pain. We designed this randomized double-blinded placebo controlled study to evaluate the control of pain after premedication with CR oxycodone 15 mg in addition to ibuprofen 800 mg orally in day-case gynaecological laparoscopic surgery.

METHODS

Sixty consenting patients were anaesthetized in a standardized fashion. Postoperative analgesia was provided by ibuprofen 800 mg twice a day in combination with fentanyl i.v. in the recovery room and normal-release (NR) oxycodone orally after the recovery room. The visual analogue scale (VAS) scores for pain and side-effects, and the amounts of postoperative analgesics were recorded for 24 h after discharge from the hospital. After a statistical analysis of the original study, we extended the study to investigate another 10 patients, who received CR oxycodone 15 mg orally in an open-labelled fashion 60 min before surgery. The plasma concentrations of oxycodone were measured from samples drawn before and 2, 4, 6 and 8 h after premedication.

RESULTS

The amounts of fentanyl [100 microg (0-330) in the CR oxycodone group; 125 microg (0-330) in the placebo group], NR oxycodone, or the VAS scores for pain during the first 24 h after the discharge from the hospital did not differ after the premedication with CR oxycodone or placebo. In the extension study group, the peak plasma concentration (C(max)) of oxycodone was 10.0 (4.6-14.7) ng ml(-1), indicating possibly a sub-therapeutic level.

CONCLUSION

Oral premedication with CR oxycodone did not improve management of postoperative pain after day-case gynaecological laparoscopic surgery.

Efficacy and Tolerability of Oxycodone Hydrochloride Controlled-Release Tablets in Moderate to Severe Cancer Pain

BACKGROUND AND OBJECTIVE

Oxycodone is a semisynthetic opioid analgesic drug classed as a strong opioid. The controlled-release oxycodone tablet formulation (OCRT) was approved in China in 2004 for management of moderate to severe cancer pain. Few data about the efficacy of OCRT and clinical outcomes in Chinese patients taking this drug are available. The purpose of this study was to evaluate the efficacy and tolerability of this drug for relief of moderate to severe cancer pain in Chinese patients.

METHODS

This was a prospective, open-label, multicentre clinical trial carried out in ten hospitals in Zhejiang Province, China. Patients with cancer pain with a score > or =4 (numerical rating scale) were enrolled. They received oral OCRT at an initial dosage of 5mg every 12 hours for patients scoring 4-6 and 10mg every 12 hours for patients scoring > or =7. Doses were then titrated on an individual basis. Onset of analgesic action, pain score and quality-of-life (QOL) scores - including items measuring family understanding and support, sleep, mental state, appetite, fatigue, and activities of daily life - were evaluated. Adverse effects were also documented.

RESULTS

216 patients (126 males and 90 females) aged 22-84 years were enrolled. The total mean OCRT dosage was 445.2 +/- 361.6mg (range 130-2320mg). The daily dosages of the vast majority of cases (89%) were between 10mg and 30mg. Onset of analgesic action occurred within 1 hour in 198 cases (91.7%) following administration of OCRT. 82.4% of cases were titrated to a steady dosage level within 2 days following administration of the first dose of medication. Pain score decreased significantly (p < 0.01) from 7.1 +/- 1.2 at baseline to 2.3 +/- 1.2 one week after starting medication and 1.8 +/- 0.9 four weeks after starting medication. Scores on all six QOL items increased significantly (p < 0.01) compared with baseline but showed varying rates of improvement. Adverse events included constipation, nausea, vomiting, drowsiness and dysuria. These were noted most frequently in the first week (25.5% of patients) and lessened over time. No severe adverse events were noted.

CONCLUSION

We conclude that OCRT is well tolerated and effective in controlling moderate to severe cancer pain in Chinese patients.

Optimizing use of opiates in the management of cancer pain

Cancer pain is often suboptimally managed. The underestimation and undertreatment continues to be a problem despite the availability of consensus-based guidelines. Most patients with cancer develop pain. The prevalence and severity of pain among cancer patients varies according to primary and metastatic sites and stage of disease. Opioid therapy is the cornerstone of management of severe chronic pain in the field of cancer patients and in general in palliative care medicine. Since this class of drugs is the cornerstone of the treatment, optimizing its use may be useful in clinical practice. For this purpose we focused on 4 distinct issues: 1) How to implement the use the opioids in cancer patients; 2) How to optimise the use of morphine in cancer patients; 3) The management of side effects and opioid switching; 4) What is the role of other potent opioids. A holistic approach including an appropriate use of opioids may improve pain control in most cancer patients, particularly for those with advanced disease.

Toward evidence-based prescribing at end of life: a comparative analysis of sustained-release morphine, oxycodone, and transdermal fentanyl, with pain, constipation, and caregiver interaction outcomes in hospice patients

OBJECTIVE

The primary goal of this investigation was to examine selected outcomes in hospice patients who are prescribed one of three sustained-release opioid preparations. The outcomes examined include: pain score, constipation severity, and ability of the patient to communicate with caregivers.

PATIENTS AND SETTINGS

This study included 12,000 terminally ill patients consecutively admitted to hospices and receiving pharmaceutical care services between the period of July 1 and December 31, 2002.

DESIGN

We retrospectively examined prescribing patterns of sustained-release morphine, oxycodone, and transdermal fentanyl. We compared individual opioids on the aforementioned outcome markers, as well as patient gender, terminal diagnosis, and median length of stay.

RESULTS

Patients prescribed a sustained-release opioid had similar average ratings of pain and constipation severity, regardless of the agent chosen. Patients prescribed transdermal fentanyl were reported to have more difficulty communicating with friends and family when compared with patients prescribed either morphine or oxycodone. On average, patients prescribed transdermal fentanyl had a shorter length of stay on hospice as compared with those receiving morphine or oxycodone.

CONCLUSION

There was no difference in observed pain or constipation severity among patients prescribed sustained-release opioid preparations. Patients receiving fentanyl were likely to have been prescribed the medication due to advanced illness and associated dysphagia. Diminished ability to communicate with caregivers and a shorter hospice course would be consistent with this profile. Further investigation is warranted to examine the correlation between a patient's ability to interact with caregivers and pain control achieved.

Evaluation of the pharmacokinetic profile and analgesic efficacy of oral morphine after total hip arthroplasty

BACKGROUND AND OBJECTIVE

Oral morphine may be useful for postoperative pain relief, but few studies have tested its use after in-hospital surgery.

METHODS

We evaluated clinical efficacy and the pharmacokinetic parameters of oral morphine after total hip arthroplasty. We recruited 60 patients who had total hip arthroplasty under general anaesthesia. The patients were randomized to receive placebo, 10 mg morphine sulphate or 20 mg morphine sulphate orally every 4 h for 24 h. The oral administration was started 3 h after the morphine-loading dose in the Post Anaesthesia Care Unit and then patients used intravenous morphine patient-controlled analgesia for 24 h. Pain score at rest (scored by patients on a visual analogue scale), sedation, nausea, vomiting and urinary retention were monitored. In 11 additional total hip arthroplasty patients, we determined the pharmacokinetics of morphine and its metabolites after oral administration of 20 mg morphine sulphate every 4 h for 16 h.

RESULTS

The amount of morphine administered via patient-controlled analgesia over 24 h was reduced in the 20-mg group compared with that in the placebo group (19.0 +/- 2.7 mg vs. 33.0 +/- 5.5 mg; P = 0.03). No significant morphine-sparing effect was observed in the 10-mg group. Pain scores and side-effects were similar in all groups. The pharmacokinetic study revealed a limited and slow absorption of morphine.

CONCLUSION

Despite a limited absorption of oral morphine postoperatively, high doses of oral morphine have a significant analgesic effect after total hip arthroplasty.

A comparative study of oxycodone and morphine in a multi-modal, tissue-differentiated experimental pain model

Visceral pain can be difficult to treat with classical mu-opioid agonists and it has been suggested to use opioids with distinct pharmacological profiles. In animal experiments, oxycodone has shown different effects compared to morphine, and clinical observations have shown that oxycodone may occasionally be superior to, e.g., morphine in the treatment of visceral pain. In the current study, we randomised 24 healthy subjects to treatment with either morphine (30 mg), oxycodone (15 mg) or placebo in a crossover study. The experimental pain model involved multi-modal (mechanical, thermal and electrical) pain tests in the skin, muscles and viscera. The pain tests were carried out at baseline and 30, 60 and 90 min after oral administration of the drugs. The model showed effect of the two opioids compared to placebo on all stimulus modalities in all three types of tissues (all P values <0.001). Both opioids attenuated the sensory response mainly to painful stimulations. Morphine and oxycodone were equipotent in pain modulation of the skin and muscles, but oxycodone had superior analgesic effect to both morphine and placebo on the mechanical (P<0.001) and thermal (P<0.001) stimulations of the oesophagus. In conclusion, the multi-modal and tissue-differentiated pain model could link findings from animal experiments to clinical findings. A different pharmacological profile of oxycodone compared to that of morphine was shown, and thus oxycodone may be a useful alternative to morphine in the treatment of visceral pain syndromes.

Oxycodone

Oxycodone has been in clinical use since 1917. Parenteral oxycodone was used mainly for the treatment of acute postoperative pain whereas combinations, for example, oxycodone and acetaminophen, were used for moderate pain. Since the introduction of controlled-release oxycodone, it has been used to manage cancer-related pain and chronic non-cancer-related pain problems. Controlled studies have been performed in postoperative pain, cancer pain, osteoarthritis-related pain, and neuropathic pain due to postherpetic neuralgia and diabetic neuropathy. The pharmacodynamic effects of oxycodone are typical of a mu-opioid agonist. Oxycodone closely resembles morphine but it has some distinct differences, particularly in its pharmacokinetic profile. Being an old drug, the basic pharmacology of oxycodone has been a neglected field of research.

The use of controlled-release versus scheduled oxycodone in the immediate postoperative period following total joint arthroplasty

This prospective study examined whether better pain control could be achieved in the first 48 hours after joint arthroplasty with controlled-release oxycodone compared to scheduled oxycodone with acetaminophen. In the study group, controlled-release oxycodone was administered on the day of surgery and was continued during patients' hospital stay. The study group then was compared to a previous group in which effective pain control was obtained with around-the-clock oxycodone with acetaminophen. Findings indicated controlled-release oxycodone did not provide better pain control compared to scheduled oxycodone with acetaminophen in the first 48 hours following total joint arthroplasty.

Simultaneous determination of oxycodone and its major metabolite, noroxycodone, in human plasma by high-performance liquid chromatography

Oxycodone (14-hydroxy-7,8-dihydrocodeinone) is a potent opioid receptor agonist. In the present study, a liquid-liquid extraction-based reversed-phase HPLC method with UV detection was validated and applied for the analysis of oxycodone and its major metabolite, noroxycodone, in human plasma. The analytes were separated using a mobile phase, consisting of acetonitrile and phosphate buffer (8:92, v/v) at a flow rate of 1 mL/min, and UV detection at 205 nm. The retention times for oxycodone, noroxycodone and codein (internal standard) were 14.7, 13.8 and 10.2 min, respectively. The validated quantitation range of the method was 2-100 ng/mL for oxycodone and 10-100 ng/mL for noroxycodone. The developed procedure was applied to assess the pharmacokinetics of oxycodone and its metabolite following administration of a single 20 mg oral dose of oxycodone hydrochloride to one healthy male volunteer.

Effectiveness and safety of oral extended-release oxymorphone for the treatment of cancer pain: a pilot study

GOALS OF WORK

Inadequate analgesia and/or unmanageable adverse events frequently result in the need to rotate patients with cancer pain to a different opioid. The availability of a novel oral extended-release (ER) formulation of oxymorphone provides clinicians with another treatment option. In this study, we assessed the analgesic effectiveness and safety of the new oral ER formulation of oxymorphone following treatment with controlled-release (CR) morphine sulfate or oxycodone.

PATIENTS AND METHODS

Adults with moderate to severe cancer pain were stabilized for > or =3 days on morphine CR or oxycodone CR, and then treated for 7 days at their stabilized dose. Drug selection was based upon patients' previous use or investigator preference. Patients were then crossed over for 7 days of treatment at an estimated equianalgesic dosage of oxymorphone ER. Pain was assessed using a visual analog scale, and adverse events were recorded.

MAIN RESULTS

A total of 86 patients entered open-label treatment. Of 34 patients assigned to morphine CR and 52 assigned to oxycodone CR, 21 (61.8%) and 42 (80.8%) completed stabilization and began treatment with oxymorphone ER, respectively; 59 of 63 (93.7%) completed treatment with oxymorphone. There were no significant differences in daily pain intensity scores between oxymorphone ER and comparators (paired t -test). Rescue medication use, expressed as the percent of the daily dose of scheduled opioid, was greater during morphine CR treatment than after crossover to oxymorphone ER (25.2% vs 13.3%; P <0.05, Wilcoxon's test). The tolerability/safety profiles (e.g., nausea, drowsiness, somnolence) were similar for all opioids.

CONCLUSIONS

Cancer patients stabilized on morphine CR or oxycodone CR were safely and rapidly converted to a lower milligram dose of oxymorphone ER that provided adequate pain relief with comparable tolerability. These results justify additional trials with oxymorphone ER.

Controlled-release oxycodone for the management of pediatric postoperative pain

Studies addressing pain management after pediatric spinal fusion surgery have focused on the use of patient-controlled or epidural analgesia during the immediate postoperative period. Controlled-release (CR) analgesics have been found to be safe and effective in adults. The purpose of this study was to describe the use of oxycodone-CR in pediatric patients after the immediate postoperative period. A retrospective chart review of 62 postoperative spinal fusion patients (10-19 years) was conducted. The mean initial oxycodone-CR dose was 1.24 mg/kg/day. The mean ratio of conversion from parenteral morphine equivalents to oxycodone-CR was 1:1. Mean pain scores decreased from 4.2/10 to 3.7/10 with the transition to oxycodone-CR. Common side effects included dizziness, constipation, and nausea. Oxycodone-CR was used for an average of 13.3 days, which included an average wean time of 6 days. Results of this study demonstrate safe and effective use of oxycodone-CR in the pediatric spinal fusion population.

Quantitative contribution of CYP2D6 and CYP3A to oxycodone metabolism in human liver and intestinal microsomes

Oxycodone undergoes N-demethylation to noroxycodone and O-demethylation to oxymorphone. The cytochrome P450 (P450) isoforms capable of mediating the oxidation of oxycodone to oxymorphone and noroxycodone were identified using a panel of recombinant human P450s. CYP3A4 and CYP3A5 displayed the highest activity for oxycodone N-demethylation; intrinsic clearance for CYP3A5 was slightly higher than that for CYP3A4. CYP2D6 had the highest activity for O-demethylation. Multienzyme, Michaelis-Menten kinetics were observed for both oxidative reactions in microsomes prepared from five human livers. Inhibition with ketoconazole showed that CYP3A is the high affinity enzyme for oxycodone N-demethylation; ketoconazole inhibited >90% of noroxycodone formation at low substrate concentrations. CYP3A-mediated noroxycodone formation exhibited a mean K(m) of 600 +/- 119 microM and a V(max) that ranged from 716 to 14523 pmol/mg/min. Contribution from the low affinity enzyme(s) did not exceed 8% of total intrinsic clearance for N-demethylation. Quinidine inhibition showed that CYP2D6 is the high affinity enzyme for O-demethylation with a mean K(m) of 130 +/- 33 microM and a V(max) that ranged from 89 to 356 pmol/mg/min. Activity of the low affinity enzyme(s) accounted for 10 to 26% of total intrinsic clearance for O-demethylation. On average, the total intrinsic clearance for noroxycodone formation was 8 times greater than that for oxymorphone formation across the five liver microsomal preparations (10.5 microl/min/mg versus 1.5 microl/min/mg). Experiments with human intestinal mucosal microsomes indicated lower N-demethylation activity (20-50%) compared with liver microsomes and negligible O-demethylation activity, which predict a minimal contribution of intestinal mucosa in the first-pass oxidative metabolism of oxycodone.

Lack of analgesic efficacy of oral delta-9-tetrahydrocannabinol in postoperative pain

We have evaluated the efficacy of delta-9-tetrahydrocannabinol (delta-9-THC), the main psychoactive constituent of cannabis, in postoperative pain. In a randomized double-blind, placebo-controlled, single-dose trial, we investigated 40 women undergoing elective abdominal hysterectomy. Randomization took place when postoperative patient-controlled analgesia was discontinued on the second postoperative day. When patients requested further analgesia, they received a single, identical capsule of either oral delta-9-THC 5 mg (n=20) or placebo (n=20) in a double-blind fashion. The primary outcome measure was summed pain intensity difference (SPID) at 6 h after administration of study medication derived from visual analogue pain scores on movement and at rest. Secondary outcome measures were time to rescue medication and adverse effects of study medication. Mean (SD) VAS pain scores before medication in the placebo and delta-9-THC groups were 6.3(2.6) and 6.4(1.3)cm on movement, and 3.2(1.9) and 3.3(0.9) on rest, respectively. There were no significant differences in mean (95% confidence interval of the difference) SPID at 6 h between the groups [placebo 7.9, delta-9-THC 4.3(-1.8 to 9.0)cm h on movement; placebo 8.8, delta-9-THC 4.9(-0.2 to 8.1)cm h at rest] and time to rescue analgesia [placebo 217, delta-9-THC 163(-22 to 130)min]. Increased awareness of surroundings was reported more frequently in patients receiving delta-9-THC (40 vs 5%, P=0.04). There were no other significant differences with respect to adverse events. This study demonstrates no evidence of an analgesic effect of orally administered delta-9-THC 5 mg in postoperative pain in humans.

Acute pain treatment for older adults hospitalized with hip fracture: current nursing practices and perceived barriers

This article examines acute pain management practices for patients 65 years of age and older who were hospitalized during 1999 for hip fracture. Data were collected from the medical records of patients (N = 709) admitted to 12 hospitals in the Midwest and from questionnaires on pain practices completed by nurses (N = 172) caring for these patients. The major variables examined were (1). pharmacological and nonpharmacological treatments for acute pain in hospitalized elders, (2). nurses' perceived stage of adoption for avoiding meperidine use and for administering analgesics around-the-clock, and (3). nurses' perceived barriers to optimal treatment of acute pain in elders. Acetaminophen was the most frequently administered analgesic, but administered doses were far less than the maximum daily recommended dose. More than one third (39%) of the nurses reported that they always avoided the use of meperidine, and over half reporting avoiding its use sometimes. However, the majority of patients (56.8%) received at least one dose of meperidine, even though evidence suggests that other analgesic agents are more appropriate for treatment of acute pain in elders. Only 27% of patients received patient-controlled analgesia, and only 22.3% of patients received around-the-clock administration during the first 24 hours after admission of analgesics that had been ordered on a prn basis. The majority of nurses were aware that around-the-clock administration of analgesics was preferable, but only 33.7% were persuaded (believed) that this method should be used. Intramuscular injection was used for 52.2% of patients, even though this route is not recommended for older adults. The most frequently used nonpharmacological intervention was repositioning, followed by use of pressure relief devices and cold application. Nurses reported difficulty contacting physicians and difficulty communicating with them about type and/or dose of analgesics as the greatest barriers to pain management. Findings from this multi-site study show that active and focused "translation" interventions are needed to promote adoption of evidence-based acute pain management practices by health care providers.