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Transdermal-controlled administration of oxycodone.

The permeability of hairless mouse skin membrane to the weak base narcotic analgesic oxycodone (pKa = 8.53) was investigated. The effects of pH on the solubility and skin permeation rate were also studied. The results of the study of skin permeation of drug through hairless mouse skin suggest that the permeability of oxycodone base is approximately 7.4 times higher than that of protonated oxycodone. The nonionic species of oxycodone, at various drug loadings, was then incorporated in a Dow-Corning silicone elastomer for the evaluation of the release rate and skin permeation rate. It was found that Q/t1/2 is directly proportional to the square root of the drug loading dose, as expected by Higuchi's equation (where Q is the cumulative amount released and t is time). However, the skin permeation rate was observed to increase initially with drug loading and level off at the loading dose of 60 mg/cm3.

Administration, Cutaneous↗

The effects of a single exposure to uncontrollable stress on the subsequent conditioned place preference responses to oxycodone, cocaine, and ethanol in rats.

RATIONALE: Acute stress has been shown to facilitate the rewarding effects of a number of commonly abused drugs, although the stressor typically must be administered either immediately before or during drug administration and often in the same environment. We have previously reported that a single session of an uncontrollable (inescapable tailshock, IS), but not controllable (escapable tailshock, ES), stressor can enhance the conditioned place preference (CPP) response to morphine, even when stressor and drug administration are separated temporally and spatially. However, this persistent, trans-situational enhancement did not occur to amphetamine CPP. OBJECTIVES: The following experiments were conducted to determine whether the long-term effects of IS on drug reward are specific to opioids. MATERIALS AND METHODS: Adult, male Sprague-Dawley rats were exposed to a single session of IS or remained in their home cages (HC). Twenty-four hours later, using an unbiased procedure, CPP conditioning was conducted with either oxycodone (0, 2, or 5 mg/kg, sc), cocaine (0, 1, 5, or 10 mg/kg, ip), or ethanol (0.3, 1, or 2 g/kg, ip). Another group of rats were exposed to IS, ES, or HC treatment and conditioned with oxycodone (5 mg/kg, sc) 24 h later. RESULTS: IS enhanced the subsequent CPP response to oxycodone, but not cocaine or ethanol. This enhancement was dependent on the controllability of the stressor, as ES did not affect oxycodone CPP. CONCLUSIONS: These results indicate that the long-term, trans-situational enhancing effect of uncontrollable stress on drug reward is specific to opioids.

Analgesics, Opioid↗

Nanogram level quantitation of oxycodone in human plasma by capillary gas chromatography using nitrogen-phosphorus selective detection.

A sensitive and specific capillary gas chromatographic assay is reported for the quantitation of oxycodone in human plasma. The technique involves a single extraction of oxycodone and internal standard (hydrocodone) from plasma by toluene containing 1% isopropanol. Separation is achieved on a methyl silicone (HP-1) fused-silica capillary column (25 m x 0.2 mm I.D., 0.33 microns film thickness) and detection is by nitrogen-phosphorus selective mode. The minimum quantifiable limit is 1.8 ng/ml using 2 ml of plasma. The method is applicable to characterize the plasma profile of oxycodone in humans after a single oral 5-mg oxycodone hydrochloride tablet.

Chromatography, Gas↗

A pharmacokinetic/pharmacodynamic study of controlled-release oxycodone.

A single-dose, analytically blinded, randomized, crossover study was conducted in 22 healthy male volunteers to compare the bioavailability of one 20 mg with two 10 mg controlled-release (CR) oxycodone tablets. In addition, pharmacodynamic effects were assessed using both objective and subjective measures for up to 48 hr after dosing. The two treatments were bioequivalent, with comparable rates (Cmax of one 20 mg tablet was 109% of two 10 mg tablets; 90% confidence limits: 98.4%-120%) and extents (AUC0-infinity: 107%; 100%-114%) of absorption. In addition, no significant differences between tablets were found for mean values of Tmax, T/12abs, or T/12elim. Correlations between plasma oxycodone concentrations and most pharmacodynamic measures were significant. The strongest correlations were observed for pupil size (r = -0.53) and subjects' assessment of drug effect (r = 0.53), with changes in plasma concentration accounting for more than 25% of the observed changes in these variables. This study demonstrated bioequivalence of two 10 mg and one 20 mg CR oxycodone tablet, with significant correlation between plasma oxycodone concentrations and pharmacodynamic effects in normal volunteers.

Adult↗

Preoperative administration of controlled-release oxycodone for the management of pain after ambulatory laparoscopic tubal ligation surgery.

STUDY OBJECTIVE: To examine the analgesic efficacy of administering controlled-release (CR) oxycodone 10 mg before elective ambulatory laparoscopic tubal ligation surgery. DESIGN: Randomized, double-blind study. PATIENTS: 50 healthy women presenting for elective ambulatory laparoscopic tubal ligation surgery. SETTING: Ambulatory surgery center of a university hospital. INTERVENTIONS: Fifty patients were administered either placebo (n = 25) or CR oxycodone 10 mg (n = 25) 1 hour before surgery. All patients were administered a similar general anesthetic. In the postanesthesia care unit (PACU), fentanyl 25 microg was administered for a verbal analog scale (VAS) pain score >or=3. Patients were discharged home when they were awake and alert, had stable vital signs, were able to void, tolerated oral fluids, experienced no side effects, had a VAS or=3. MEASUREMENTS: VAS pain scores and the frequency of postoperative nausea and vomiting were recorded in the PACU. While at home, patients were contacted by telephone after surgery and asked about their pain score, time to first analgesic use, frequency of postoperative nausea and vomiting, and total acetaminophen/oxycodone use in the 24 hours following surgery. MAIN RESULTS: Patients in the CR oxycodone group had a shorter time to discharge (p < 0.001), reported lower postoperative pain scores (p < 0.001), lower frequency of postoperative nausea and vomiting (p < 0.05), longer time to first analgesic use (p < 0.0,001), and required less fentanyl in the PACU (p < 0.01) and fewer acetaminophen/oxycodone tablets in the 24 hours following surgery. CONCLUSION: The preoperative administration of CR oxycodone 10 mg is an effective analgesic technique in the management of pain following ambulatory laparoscopic tubal ligation surgery, and may facilitate earlier postoperative discharge.

Adult↗

Discriminative stimulus, reinforcing, physical dependence, and antinociceptive effects of oxycodone in mice, rats, and rhesus monkeys.

Despite oxycodone's (4,5-epoxy-14-hydroxy-3-methoxy-17-methylmorphinan-6-one) history of clinical use and the attention it has received as a drug of abuse, few reports have documented its pharmacology's relevance to its abuse or its mechanism of action. The purposes of the present study were to further characterize the analgesic effects of oxycodone, its mechanism of action, and its effects in terms of its relevance to its abuse liability. The results indicate that oxycodone had potent antinociceptive effects in the mouse paraphenylquinone writhing, hot-plate, and tail-flick assays, in which it appeared to be acting as a mu-opioid receptor agonist. It generalized to the heroin discriminative stimulus and served as a positive reinforcer in rats and completely suppressed withdrawal signs in morphine-dependent rhesus monkeys. These results suggest that the analgesic and abuse liability effects of oxycodone are likely mediated through mu-opioid receptors and provide the first laboratory report of its discriminative stimulus, reinforcing, and morphine cross-dependency effects.

Analysis of Variance↗

Ventilatory responses of healthy subjects to intravenous combinations of morphine and oxycodone under imposed hypercapnic and hypoxaemic conditions.

AIMS: Previous isobolographic analysis revealed that coadministration of morphine and oxycodone produces synergistic antinociception in laboratory rodents. As both opioids can produce ventilatory depression, this study was designed to determine whether their ventilatory effects were synergistic when coadministered to healthy human subjects. METHODS: A placebo-controlled, randomized, crossover study was performed in 12 male volunteers. Ventilatory responses to hypoxaemia and hypercapnia were determined from 1-h intravenous infusions of saline ('placebo'), 15 mg morphine sulphate (M), 15 mg oxycodone hydrochloride (O), and their combination in the dose ratios of 1:2, 1:1, 2:1. Drug and metabolite concentrations in serial peripheral venous blood samples were measured by high-performance liquid chromatography-MS/MS. RESULTS: 'Placebo' treatment was without significant ventilatory effects. There were no systematic differences between active drug treatments on either the slopes or intercepts of the hypoxaemic and hypercapnia ventilation responses. During drug treatment, the mean minute ventilation at PetCO(2) = 55 mmHg (V(E55)) decreased to 74% of the subjects' before treatment values (95% confidence interval 62, 87), 68% (57, 80), 69% (59, 79), 68% (63, 73), and 61% (52, 69) for M15, M10/O5, M7.5/O7.5, M5/O10 and O15, respectively. Recovery was more prolonged with increasing oxycodone doses, corresponding to its greater potency and lower clearance compared with morphine. CONCLUSIONS: Although adverse ventilatory effects of these drugs were found as expected, no unexpected or disproportionate effects of any of the morphine and oxycodone treatments were found that might impede their use in combination for pain management.

Adolescent↗

Intravenous morphine and oxycodone for pain after abdominal surgery.

Intravenous morphine and oxycodone were given double blind in doses of 0.05 mg/kg after major abdominal surgery to 39 patients. The dosing interval was 5 min, until the patient did not want any further analgesics. Less oxycodone was needed than morphine, both to achieve the "first state of pain relief" (13.2 mg vs. 24.9 mg) and during the whole 2-h study period (21.8 mg vs. 34.2 mg). The "first state of pain relief" was achieved faster (28 min vs. 46 min) and lasted longer (39 min vs. 27 min) with oxycodone than morphine. Morphine caused more sedation and a greater decrease in the mean arterial blood pressure than oxycodone. In other respects the two opioids were comparable.

Abdomen↗

Laboratory monitoring of OxyContin (oxycodone): clinical pitfalls.

Some patients have headaches that are refractory to standard treatments, and they require chronic administration of opioid analgesics. The use of opioids in a clinical setting must be closely monitored due to the medications' potential for addiction, abuse, and fatal interactions. Limited access to opioids and the demand for them outside the clinical setting leads to another danger. Patients can mislead their providers into prescribing opioids, intending to sell the medications instead of using them to alleviate their own pain. For protection of the patient, as well as the community, it is vital that such activity be prevented. We recently encountered a patient we suspected of abusing or misusing OxyContin (oxycodone). In order to determine whether the patient was taking the medication as prescribed, we ordered a urine-based immunoassay drug screen. The results were negative; the patient appeared to not have oxycodone in his system. Based on these results, we dismissed the patient from our practice. At the patient's request, a second test was performed, this time using gas chromatography-mass spectrometry. It indicated that the patient did indeed have sufficiently high levels of oxycodone in the urine. The minimum level threshold was too high to detect the presence of oxycodone in the immunoassay. We would like to help prevent future misunderstandings such as we experienced. To do so, we will first present the case of our patient, followed by a discussion of the actions taken. Finally, we will provide an overview of analgesic monitoring systems.

Adult↗

Lack of interaction between levofloxacin and oxycodone: pharmacokinetics and drug disposition.

Previous studies have demonstrated a significant reduction in the oral bioavailability of trovafloxacin and ciprofloxacin when administered concomitantly with an intravenous opiate such as morphine. This decrease in absorption results in a 36% and 50% lower AUC for trovafloxacin and ciprofloxacin, respectively, which could cause clinical failures. The authors investigated the possibility of a similar interaction between oxycodone and levofloxacin. Eight healthy volunteers were randomized in an open-label, two-way crossover study to receive oxycodone, 5 mg p.o. Q4H, and levofloxacin, 500 mg p.o. 1 hour after starting the oxycodone or levofloxacin 500 mg p.o. alone. Blood samples were drawn at 0, 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, 18, and 24 hours for Cmax, tmax, and AUC determinations. There was not a significant difference (p > 0.05) in AUC (48.59 +/- 8.52 vs. 49.9 +/- 9.93), Cmax (7.73 +/- 2.6 vs. 6.6 +/- 2.0), and tmax (1.1 +/- 0.6 vs. 1.6 +/- 1.1) for levofloxacin versus levofloxacin/oxycodone regimens. It was concluded that oral oxycodone and levofloxacin can be administered concomitantly without a significant decrease in AUC, Cmax, or tmax.

Adult↗

Minimal interaction between gatifloxacin and oxycodone.

Previous studies have demonstrated a significant reduction in the oral bioavailability of trovafloxacin and ciprofloxacin when administered concomitantly with an intravenous opiate, such as morphine. This decrease in absorption results in a 36% and 50% lower AUC for trovafloxacin and ciprofloxacin, respectively, which could cause clinical failures. The authors investigated the possibility of a similar interaction between oxycodone and gatifloxacin. Twelve healthy volunteers were randomized in an open-label, two-way crossover study to receive oxycodone (5 mgpo Q4H) andgatifloxacin (400 mg po 1 h) after starting the oxycodone or gatifloxacin 400 mg po alone. Blood samples were drawn at 0, 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, 18, and 24 hours postdosing. No significant difference was noted (p > 0.05) in AUC (31.6 +/- 7.3 vs. 31.7 +/- 7.1) and Cmax (3.2 +/- 0.6 vs. 3.0 +/- 0.6) for gatifloxacin versus gatifloxacin/oxycodone regimens; however, the tmax (1.8 +/- 0.8 vs. 4.3 +/- 1.5) was significantly delayed (p < 0.001). It was concluded that oral oxycodone and gatifloxacin can be administered concomitantly without a significant decrease in bioavailability.

Adolescent↗

Comparison of valdecoxib and an oxycodone-acetaminophen combination for acute musculoskeletal pain in the emergency department: a randomized controlled trial.

UNLABELLED: Oral opioids are potent analgesics that are used to treat acute pain in the emergency department (ED). However, they are associated with adverse events such as sedation that may delay safe patient discharge. OBJECTIVE: To compare the safety and efficacy of a new cyclooxygenase-2 inhibitor, valdecoxib, with those of an oxycodone-acetaminophen combination in patients with acute musculoskeletal pain. METHODS: This was a double-blind, randomized controlled trial at an immediate care section of a suburban university-based ED with an annual census of 75,000. Adults with acute musculoskeletal pain without contraindications to the study medications were included. After recording their initial pain scores, patients were randomized to either oral valdecoxib 40 mg or oxycodone 10 mg with acetaminophen 650 mg. Pain scores were recorded at 30 and 60 minutes, and patients who requested additional pain relief were given an oral analgesic at the physician's discretion. Twenty-four-hour telephone follow-up was performed. The pain severity was recorded at 0, 30, and 60 minutes using a validated 100-mm visual analog scale marked "most" at the high end. The need for rescue medications and the occurrence of adverse events were determined. Study outcomes were compared with Student's t-test, repeated-measures analysis of variance (ANOVA), and chi(2) tests as appropriate. RESULTS: Fifty-one patients were randomized to valdecoxib (26) or oxycodone (25). Mean (+/- SD) age was 36 (+/- 14.7) years; 49% were women. Pain locations included extremities (49%), neck (29%), and back (22%). Baseline patient characteristics and pain severities were similar. There was no between-group difference in pain scores at 30 and 60 minutes. The changes in pain scores over time were also similar in the two study groups (repeated-measures ANOVA, p = 0.32). Patients treated with valdecoxib were less likely to experience sedation/dizziness (15% vs. 44%, p = 0.03) and to require rescue medications within the next 24 hours (44% vs. 74%, p = 0.04). CONCLUSIONS: Valdecoxib is as effective as an oxycodone-acetaminophen combination in treating ED patients with acute musculoskeletal pain at 30 minutes and less likely to cause sedation or the need for rescue analgesia over the next day.

Acetaminophen↗

The use of oxycodone in cancer-related pain: a literature review.

Oxycodone is a semi-synthetic opioid agonist that can be used as an alternative to morphine in controlling cancer pain. It differs from morphine in its biphasic qualities in controlled release (CR) formulation. This review of post-1995 international literature explores the use of oxycodone compared with morphine, as well as titration studies comparing CR formulation against the conventional immediate release (IR) formulation. Most studies involved small numbers and so their results cannot be generalized. Statistical tests were used inappropriately in several of the studies reviewed, which compromises the validity of the findings, but it is important to note that there was broad agreement between researchers. Studies were graded based on research quality criteria of the US Agency for Health Care Policy and Research (United States Department for Health and Human Services, 1993). Conversion ratios and side-effects are discussed and recommendations made for the use of oxycodone in opioid rotation, particularly for patients suffering morphine-induced hallucinations. Several studies also recommend the use of oxycodone in preference to morphine in patients with renal impairment.

Analgesics, Opioid↗

A randomized trial of controlled-release oxycodone during inpatient rehabilitation following unilateral total knee arthroplasty.

BACKGROUND: Reliance on "as-needed" analgesia following total knee arthroplasty may lead to inadequate control of pain and delayed recovery of function. Preemptive use of controlled-release opioids may improve pain control, accelerate recovery, and reduce the need for inpatient rehabilitative services. This study was designed to determine whether controlled-release opioids enhance post-arthroplasty pain control and facilitate functional recovery during rehabilitation. METHODS: Fifty-nine patients admitted for inpatient rehabilitation following unilateral total knee arthroplasty were randomized to receive OxyContin (controlled-release oxycodone) (twenty-nine patients) or a placebo (thirty patients) every twelve hours. Both groups could receive on-request, immediate-release oxycodone (5 mg every four hours). The dose of study medication was increased on the basis of the frequency of requests for immediate-release oxycodone. Measures of interest included pain ratings as determined with a visual-analog scale, changes in the range of motion of the knee and quadriceps strength, and improvements in selected Functional Independence Measure scores during the first eight physical therapy sessions. The duration of the hospital stay for rehabilitation also was compared between the two groups. RESULTS: Baseline demographic, clinical, and functional characteristics were similar between the OxyContin and placebo groups. Compared with the placebo group, the patients who received OxyContin reported significantly less pain as well as significantly greater range of motion of the knee (passive motion, p = 0.036; active motion, p< 0.001) and quadriceps strength (p = 0.001) by the eighth physical therapy session. The patients who received OxyContin also were discharged from the rehabilitation hospital at an average of 2.3 days earlier than the patients in the placebo group (p = 0.013). CONCLUSIONS: Preemptive use of controlled-release oxycodone during rehabilitation following total knee arthroplasty leads to improved pain control, more rapid functional recovery, and a reduced need for inpatient rehabilitative services.

Aged↗

[Controlled release oxycodone--a new option in the treatment of severe and very severe pain. Review of studies on neuropathic, physical activity-related and postoperative pain].

Opioids are used not only in the treatment of cancer pain, but also pain of non-malignant genesis. In recent years, the efficacy of controlled release (CR) oxycodone in the treatment of the above-mentioned types of pain has been investigated in a number of clinical studies. The present article reviews the clinical studies that have been already published. Thanks to its outstanding pharmacological and pharmacodynamic properties, CR oxycodone is fast acting and brings about long lasting pain relief, coupled with benefits for physical and mental activities. This results in a significant quality-of-life improvement. Oral therapy with CR oxycodone is safe and can be precisely controlled. Since there are no clinical relevant metabolites, there is no danger of accumulation in patients with renal infarction due to these metabolites. Side effects are those typical for opioids, and are readily manageable. CR oxycodone is a good alternative in the treatment of non-cancer pain and can be recommended as first-line treatment for the above-mentioned indications.

Administration, Oral↗

Comparison of intravenous diclofenac, indomethacin and oxycodone as post-operative analgesics in patients undergoing knee surgery.

The non-steroidal anti-inflammatory drugs diclofenac, indomethacin and oxycodone were compared in the treatment of pain after arthroscopy or arthrotomy of the knee in a double-blind, randomized trial. A single and, if needed, a repeated dose of one of the following six dose and drug alternatives was given intravenously for post-operative pain relief: diclofenac 37.5 mg or 75 mg, indomethacin 25 mg or 50 mg and oxycodone 5 mg or 10 mg. Oxycodone 5 mg i.v. was used as a rescue medication whenever the patient needed further pain relief after the two doses of the trial drugs. The observation period was 14 h. In the diclofenac group the patients needed significantly less trial and rescue analgesics than in the indomethacin (P less than 0.001) and oxycodone (P less than 0.05) groups, the latter groups being equal in this respect. Both the duration from the first trial drug infusion to the second trial medication and to the first rescue medication were significantly longer in the diclofenac group than in the indomethacin group (P less than 0.05 and less than 0.01, respectively).

Adult↗

Isolation and identification of urinary metabolites of oxycodone in rabbits.

Metabolism of oxycodone was studied in the rabbit and found to proceed through five metabolic pathways: O-demethylation, N-demethylation, N-oxidation, 6-keto reduction, and glucuronidation. Six urinary metabolites were isolated and identified in the unconjugated form: 14-hydroxydihydromorphinone, 14-hydroxydihydrocodeine, 14-hydroxydihydrocodeinone N-oxide (oxycodone N-oxide), 14-hydroxydihydroisocodeine, 14-hydroxydihydrocodeine N-oxide, and noroxycodone, together with unchanged oxycodone. Identification was made by means of various chromatographic and spectral comparisons with authentic samples. Oxycodone, 14-hydroxydihydromorphinone, 14-hydroxydihydrocodeine, 14-hydroxydihydroisocodeine, and noroxycodone were also identified as aglycons of conjugated metabolites.

Animals↗

A study of deaths involving oxycodone.

Nine deaths involving oxycodone were investigated to assess the contribution of this opiate to these fatalities. All except one of the bodies were subjected to a full autopsy by specialist pathologists with a subsequent thorough toxicological examination. No significant anatomical pathology was found at autopsy. All deaths gave concentrations of oxycodone in femoral blood higher than expected following normal therapeutic use. In three cases no other drug in toxic concentrations was detected. Two cases involved the presence of a high concentration of a benzodiazepine and in a further two cases a high concentration of alcohol in addition to other drugs in therapeutic concentrations were present. One case involved methamphetamine in significant concentrations and another involved high concentrations of oxazepam in combination with pethidine. In all cases the presence of oxycodone was given as a factor contributing to the death. In only one case were there circumstances clearly indicating suicide. Our observations suggest that oxycodone is at least as toxic as other opiates and will cause deaths if misused.

Adult↗