Opioid responsiveness of cancer pain syndromes caused by neuropathic or nociceptive mechanisms: a combined analysis of controlled, single-dose studies.

We performed a combined analysis of the results from four controlled single-dose relative-potency studies to assess the impact of inferred pain mechanism on the response to an opioid drug. A total of 168 patients received 474 administrations of either morphine or heroin, and we assessed the analgesic response during a 6-hour period with visual analog scales. We summarized this as a total pain relief (TOTPAR) score. Two experienced pain clinicians reviewed information about pain characteristics and designated each case according to the inferred pain mechanism (neuropathic, nociceptive, or mixed) and the degree of confidence in the inferred mechanism (definite versus probable/possible). They grouped the cases as follows: nociceptive pain only (n = 205), neuropathic pain only (n = 49), and mixed (n = 220). We compared pain relief achieved by patients with different mechanisms, with TOTPAR adjusted for significant covariates (duration of prior opioid administration, doses of opioid administered in the previous 48 hours, pain intensity at the start of the study, BUN:creatinine ratio, and dose of administered opioid). The adjusted mean TOTPAR score of the group with any neuropathic pain was significantly lower than that of the group with nociceptive pain only (26.1 versus 20.4, p = 0.02). The score of the group with definite nociceptive pain alone (adjusted mean TOTPAR = 28.0) was significantly higher than scores of the groups with possible/probable nociceptive pain (TOTPAR = 19.9), mixed mechanisms (TOTPAR = 20.2), definite neuropathic pain alone (TOTPAR = 20.6), and possible/probable neuropathic pain alone (TOTPAR = 22.9).(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic morphine therapy for cancer pain: plasma and cerebrospinal fluid morphine and morphine-6-glucuronide concentrations.

Morphine-6-glucuronide (M-6-G) is an active metabolite that may contribute to the clinical effects produced by systemic administration of morphine. To help clarify the extent to which M-6-G may cross the blood-brain barrier and exert effects, we employed high-performance liquid chromatography with electrochemical detection to measure the concentrations of M-6-G and morphine in the plasma and either ventricular (three patients) or lumbar (eight patients) CSF of cancer patients receiving chronic morphine therapy. The mean ratio of morphine in ventricular CSF:morphine in plasma was 0.71; the same ratio for M-6-G was only 0.077. The average molar ratio of M-6-G: morphine in ventricular CSF was 0.207, and the average molar ratio in plasma was 1.89. Although sampling problems render the lumbar CSF results less reliable, they were very similar. Thus, plasma contained approximately twice as much M-6-G as morphine, whereas CSF contained only one-fifth to one-third as much. These data confirm that M-6-G in plasma is distributed into CSF, but to a far lesser extent than morphine. They help explain animal data demonstrating much higher potency of M-6-G on administration into CSF than systemic administration and indicate that the degree to which M-6-G contributes to morphine effects in humans remains an unresolved question.

L-carnitine supplementation for the treatment of fatigue and depressed mood in cancer patients with carnitine deficiency: a preliminary analysis.

Nutritional factors are among the postulated causes of fatigue, a highly prevalent symptom in the cancer population, with serious impact on patients' quality of life. Deficiency of the micronutrient carnitine may play a role by reducing energy production through fatty acid oxidation. We present preliminary data of an open-label, dose-finding study to determine safety and maximally tolerated dose (MTD) of 1 week of L-carnitine supplementation in cancer patients with fatigue and carnitine deficiency. Patients who met inclusion/exclusion criteria underwent carnitine level determination. Eighty-three percent of these patients (15/18) had carnitine deficiency. Preliminary data analysis of 13 patients showed that total carnitine increased from 30.0 +/- 6.9 to 41.0 +/- 12.1 (mean +/- SD) after 1 week of supplementation (P = 0.01), and free carnitine increased from 24.3 +/- 6.1 to 33.8 +/- 9.8 (P = 0.004). Outcome measures were fatigue (BFI score), depression (CES-D), sleep disruption (ESS), and performance status (Karnofsky). Median (min, max) BFI score at baseline was 73 (46, 82) versus 50 (3, 82) after 1-week supplementation (P = 0.009). CES-D score at baseline was 29 (16, 42) and 22 (8, 32) after 1 week (P = 0.028). ESS at baseline was 46.5 (0, 69) and 30.4 (0, 72) after 1 week (P = 0.015). Karnofsky score did not change significantly (P = 0.38). We are currently conducting a randomized, double-blind, placebo-controlled study to rigorously assess the role of L-carnitine for the treatment of fatigue and depression in cancer patients.

Cancer pain management with a controlled-release oral morphine preparation.

An open-label pilot study was conducted to assess the efficacy and acceptability of a controlled-release oral morphine formulation, MS Contin tablets, when administered "by the clock" two to three times daily as a substitute for opioids given on request to patients with pain caused by advanced cancer. Initially, four-hourly does of standard "immediate-release" oral morphine sulfate tablets were substituted for the patients' prior analgesic medication and titrated to individual needs. Forty of the 47 patients enrolled in the study were subsequently switched to an eight-hourly MS Contin regimen (three patients became too ill to continue the study, and four left the study during the immediate-release titration phase because of adverse reactions that may have been drug related). Small "rescue" doses of standard oral morphine were available to the patients, but they were taken infrequently. Twenty-one of the 37 patients maintained on the eight-hourly schedule consented to be treated with, and were subsequently stabilized on, MS Contin administered every 12 hr, with a reduction of over 20% in their average daily morphine dose. Most of the patients rated the controlled-release medication superior to the standard oral morphine tablets in terms of both convenience and adequacy of relief.

The measurement of symptoms in children with cancer.

The purpose of this study was to determine symptom prevalence, characteristics, and distress in children with cancer. The Memorial Symptom Assessment Scale (MSAS) 10-18, a 30-item patient-rated instrument adapted from a previously validated adult version, provided multidimensional information about the symptoms experienced by children with cancer. This instrument was administered to 160 children with cancer aged 10-18 (45 inpatients, 115 outpatients). To confirm the instrument's reliability and validity, additional data about symptoms were collected from both the parents and the medical charts, and retesting was performed on a subgroup of inpatients. Patients could easily complete the scale in a mean of 11 minutes. The analyses supported the reliability and validity of the MSAS 10-18 subscale scores as measures of physical, psychological, and global symptom distress, respectively. Symptom prevalence ranged from 49.7% for lack of energy to 6.3% for problems with urination. The mean (+/- SD) number of symptoms per inpatient was 12.7 +/- 4.9 (range, 4-26), significantly more than the mean 6.5 +/- 5.7 (range, 0-28) symptoms per outpatient. Patients who had recently received chemotherapy had significantly more symptoms than patients who had not received chemotherapy for more than 4 months (11.6 +/- 6.0 vs. 5. 2 +/- 5.1), and those patients with solid tumors had significantly more symptoms than patients with either leukemia, lymphoma, or central nervous system malignancies (9.9 +/- 7.0 vs. 6.8 +/- 5.5 vs. 6.8 +/- 5.0 vs. 8.0 +/- 6.1). The most common symptoms (prevalence > 35%) were lack of energy, pain, drowsiness, nausea, cough, lack of appetite, and psychological symptoms (feeling sad, feeling nervous, worrying, feeling irritable). Of the symptoms with prevalence rates > 35%, those that caused high distress in more than one-third of patients were feeling sad, pain, nausea, lack of appetite, and feeling irritable. Subscale scores demonstrated large variability in symptom distress and could identify subgroups with high distress. The prevalence, characteristics, and distress associated with physical and psychological symptoms could be quantified in older children with cancer. The data confirm a high prevalence of symptoms overall and the existence of subgroups with high distress associated with one or multiple symptoms. Symptom distress is relatively higher among inpatients, children with solid tumors, and children who are undergoing antineoplastic treatment. Systematic symptom assessment may be useful in future epidemiological studies of symptoms and in clinical chemotherapeutic trials. Symptom epidemiology may also provide a focus for future clinical trials related to symptom management in children with cancer.

Guidelines for use of controlled-release oral morphine in cancer pain management. Correlation with clinical experience.

An open study of 47 patients with cancer pain treated with repeated doses of a controlled-release oral morphine tablet was conducted to assess the acceptability of this drug and develop guidelines for its use. Each patient kept a detailed record of pain, analgesic intake, side effects, and other medications. A nurse observer/clinician followed these patients on a daily basis and kept similar records. Of 47 patients who began the study, 37 were successfully stabilized with standard morphine sulfate tablets and then switched to controlled-release morphine (CRM). Twenty-one patients who completed the study took CRM every 12 h, and 16 patients received a dose every 8 h. Doses of the CRM ranged from 30 mg every 12 h to 360 mg every 8 h. Less frequent doses and uninterrupted sleep were reported advantages. All of the patients completing the study chose to continue this method of pain management and extended care data were obtained from each patient poststudy through continued monitoring.

Transdermal fentanyl for cancer pain. Repeated dose pharmacokinetics.

BACKGROUND: The transdermal therapeutic system (fentanyl), or TTS(fentanyl), continuously delivers fentanyl for up to 72 h. The transdermal therapeutic system (fentanyl)-100 delivers approximately 100 micrograms/h. The repeated dose pharmacokinetics of this drug using the recommended dosing interval have not been evaluated previously and were determined in the present study. METHODS: Blood samples were obtained from ten opioid-tolerant cancer patients who received five applications of TTS(fentanyl) at 72-h intervals. A sample of venous blood was taken before each dose; multiple samples were taken during and after the fifth application. A gas chromatographic/mass spectrometry method was used to assay fentanyl (limit of detection 0.2 ng/ml). RESULTS: For the fifth dose, the mean (SD) maximum concentration was 2.6 (1.3) ng/ml and the mean (SD) area under the serum fentanyl concentration-time curve (0-72 h) was 116.9 (59.9). Following removal of the system, the mean (SD) apparent half-life was 21.9 (8.9) h. There were no differences among the serum fentanyl concentrations measured before the second through fifth doses. Fentanyl absorption was 47% complete at 24 h, 88% complete at 48 h, and 94% complete at 72 h. The mean (SD) dose delivered during the 72-h period was 4.3 (1.1) mg. A first-dose trough concentration predicted from fifth-dose kinetics and the actual first-dose trough concentration were very similar. Adverse effects ascribed to the transdermal system were minimal. CONCLUSIONS: These results suggest that steady-state serum concentrations are approached by the second dose of TTS(fentanyl) and that the kinetics are stable with repeated dosing. The apparent half-life following system removal is relatively long, indicating ongoing absorption from a subcutaneous depot.

Transdermal fentanyl in children with cancer pain: feasibility, tolerability, and pharmacokinetic correlates.

OBJECTIVES: (1) To assess the feasibility and tolerability of the therapeutic transdermal fentanyl system (TTS-fentanyl) by using a clinical protocol developed for children with cancer pain. (2) To estimate the pediatric pharmacokinetic parameters of TTS-fentanyl. METHODS: The drug was administered in open-label fashion; and measures of analgesia, side effects, and skin changes were obtained for a minimum of 2 doses (6 treatment days). Blood specimens were analyzed for plasma fentanyl concentrations. The pharmacokinetics of TTS-fentanyl were estimated by using a mixed effect modeling approach. RESULTS: Treatment was well tolerated. Ten of the 11 patients who completed the 2 doses continued treatment with TTS-fentanyl. The duration of treatment ranged from 6 to 275 days. The time to reach peak plasma concentration ranged from 18 hours to >66 hours in patients receiving the 25 microg/h patch. Compared with published pharmacokinetic data from adults, the mean clearance and volume of distribution of transdermal fentanyl were the same, but the variability was less. CONCLUSIONS: Treatment of children with TTS-fentanyl is feasible and well tolerated and yields fentanyl pharmacokinetic parameter estimates similar to those for adults. A larger study is required to confirm these findings and further test the clinical protocol.