Raymond W. Houde

The memorial pain assessment card. A valid instrument for the evaluation of cancer pain

Effective evaluation and treatment of cancer pain require valid and independent measurement of pain intensity, pain relief, and psychological distress. The Memorial Pain Assessment Card (MPAC) is a simple instrument designed to provide rapid evaluation of these subjective experiences. On the 8.5 by 11 inch card are printed the eight pain intensity descriptors, and three visual analog scales which measure pain intensity, pain relief, and mood. Experienced patients can complete it in less than 20 seconds. The authors administered the MPAC to 50 hospitalized cancer patients within 48 hours of referral to the Pain Service for inadequate pain control, together with standard measures: The McGill Pain Questionnaire, Profile of Mood States, Hamilton Depression Scale, and Zung Anxiety Scale. Correlational and multiple regression analyses revealed that the MPAC can distinguish pain intensity from pain relief and from general psychological distress, and it can provide multidimensional assessment that is practically equivalent to the full assessment battery. We conclude that the MPAC is valid and effective for clinical use, and recommend it for the assessment of individual patients, and as an outcome measure in clinical trials.

SUBLINGUAL ABSORPTION OF SELECTED OPIOID ANALGESICS

Ongoing interest in the improvement of pain management with opioid analgesics has led to the investigation of sublingual opioid absorption. The present report determined the percent absorption of selected opioid analgesics from the oral cavity of normal subjects under conditions of controlled pH and swallowing when a 1.0 ml aliquot of the test drug was placed under the tongue for a 10‐minute period. Compared with morphine sulfate at pH 6.5 (18% absorption), buprenorphine (55%), fentanyl (51%), and methadone (34%) were absorbed to a significantly greater extent (p < 0.05), whereas levorphanol, hydromorphone, oxycodone, heroin, and the opioid antagonist naloxone were not. Overall, lipophilic drugs were better absorbed than were hydrophilic drugs. Plasma morphine concentration‐time profiles indicate that the apparent sublingual bioavailability of morphine is only 9.0% ± 11.9% (SD) of that after intramuscular administration. In the same subjects the estimated sublingual absorption was 22.4% ± 9.2% (SD), indicating that the sublingual absorption method may overestimate apparent bioavailability. When the oral cavity was buffered to pH 8.5, methadone absorption was increased to 75%. Thus, an alkaline pH microenvironment that favors the unionized fraction of opioids increased sublingual drug absorption. Although absorption was found to be independent of drug concentration, it was contact time dependent for methadone and fentanyl but not for buprenorphine. These results indicate that although the sublingual absorption and apparent sublingual bioavailability of morphine are poor, the sublingual absorption of methadone, fentanyl, and buprenorphine under controlled conditions is relatively high.

Pharmacokinetics and pharmacodynamics of methadone in patients with chronic pain

Concentrations of methadone in plasma, estimates of pain relief, and pupillary size were determined after a single intravenous dose (10 to 30 mg) of methadone hydrochloride to eight patients with chronic pain, five of whom had cancer. The pharmacokinetic parameter estimates reveal rapid and extensive distribution (Varea) and a slow apparent elimination half‐life (t½) (mean Varea = 3.59 L/kg and harmonic mean t½ = 23 hours). The harmonic mean blood clearance is 106 ml/min, the harmonic mean renal clearance is 3.9 ml/min, the mean hepatic extraction ratio is 0.089, and plasma protein binding is 86% to 89%. These results suggest that only the free (unbound) fraction of methadone present in blood is extracted by the liver and that methadone can be classified as a low (hepatic)‐extraction drug. The data were fit to a pharmacokinetic‐pharmacodynamic model to obtain estimates of the steady‐state plasma methadone concentration required to produce 50% of the maximum pain relief. This value varied from 0.04 to 1.13 μg/ml (mean = 0.29 μg/ml). These results indicate substantial interindividual variation in the relationship between changes in plasma methadone concentration and analgesia in patients with chronic pain receiving opioids. A pharmacokinetic‐pharmacodynamic model may be useful for the individualization of analgesic dosage and therefore the optimization of pain management in patients with chronic pain.

Sources of variation in analgesic responses in cancer patients with chronic pain receiving morphine

Abstract Our objective was to identify and quantify sources of variation in the relief of chronic pain with morphine. Relief scores were extracted from records obtained during controlled trials of analgesics in cancer patients with chronic pain in which intramuscular morphine was the assay standard. Relief data from 715 patients after 565 8‐mg and 538 16‐mg doses were segregated according to age, race, sex, pre‐drug pain intensity, character and site. Middle‐aged patients obtained relief after 8 mg comparable to relief obtained by younger patients after 16 mg; oldest patients obtained relief after 8 mg comparable to relief obtained by middle‐aged patients after 16 mg. Blacks receiving 8 mg obtained relief comparable to whites receiving 16 mg. Sex‐related differences were not significant. Patients with moderate, as compared to severe, pre‐drug pain obtained significantly greater relief only after 16 mg. Patients reporting dull pain obtained relief after 8 mg comparable to relief obtained with sharp pain after 16 mg. Patients with abdominal pain obtained relief after 8 mg comparable to relief of pain in the chest or arms after 16 mg. These results provide dose‐related evidence of variation in relief with morphine in chronic cancer pain and establish particular patient and pain characteristics as variables for which controls

Relative Analgesic Potency of Oral Zomepirac and Intramuscular Morphine in Cancer Patients with Postoperative Pain

A twin crossover assay of oral zomepirac and intramuscular morphine was completed in 159 cancer patients with postoperative pain. Zomepirac was a surprisingly effective oral analgesic in these patients, 100 mg orally being roughly equivalent to 16 mg intramuscular morphine. Time-effect data indicate that the peak effect for oral zomepirac may occur slightly later than that for morphine but that zomepirac is relatively rapidly effective after oral administration. Side effect occurrence was roughly in the same range for both drugs, with drowsiness, nausea, dry mouth, and feelings of weakness being observed after both drugs while sweating was observed more frequently after zomepirac. The assay further provided a demonstration of the effectiveness of the twin crossover design as a clinical assay method, providing increased sensitivity of crossover data in a patient population available for only a limited number of study treatments.

Clinical analgesic assay of repeated and single doses of heroin and hydromorphone

&NA; A direct comparison of the analgesic activities of heroin and hydromorphone was carried out in cancer patients with postsurgical pain. Intramuscular doses of 5 and 10 mg of heroin were compared with 1 and 2 mg of hydromorphone in a randomized, double‐blind, 4‐point parallel group assay. Design innovations in the study provided that about half the patients would receive prior repeated doses of the same drug as the test medication and half would receive the alternate medication. Both test drugs were found to be potent, relatively short acting analgesics with similar profiles of action. Hydromorphone was about 5 times as potent as heroin on a milligram basis. The comparison of those patients who had repeated doses of the same treatment prior to the test dose and those who had repeated doses of the alternate drug demonstrated no significant effect on the relative potency estimates. Side effect occurrence was similar for both drugs, with sleepiness the most prominent effect. The study supports the view that hydromorphone and heroin produce similar clinical effects and that either drug may adequately substitute for the other. Covariate analysis indicated that time since last analgesic was positively related to analgesia and amount of prior opioid had a negative relationship. To a lesser extent, increase in patient age was associated with an increase in analgesic scores. Taking these covariates into account served to increase the sensitivity of the analysis.

Cocaine and morphine interaction in acute and chronic cancer pain

&NA; An evaluation of the analgesic, mood and side effects of the combination of intramuscular morphine and oral cocaine was conducted in 17 patients with postoperative pain and 19 others with chronic malignant pain for the purpose of assessing the therapeutic merits of so‐called ‘euphoriant’ elixirs in the management of pain in cancer patients. The study was designed as a randomized and double‐blind single dose but complete cross‐over comparison of the combination of 10 mg intramuscular morphine and 10 mg oral cocaine with morphine alone, cocaine alone, and placebo. While patients clearly discriminated between the analgesic effects of morphine and placebo, there were no differences in the analgesic responses to cocaine and placebo, or in responses to morphine and the combination of morphine and cocaine in either patient group. Side effects were predominantly morphine‐like and occurred in 59% of patients after the combination, 43% after morphine, 34% after cocaine and 25% after placebo. Interaction effects between cocaine and morphine were observed in terms of positive changes toward selected aspects of mood (e.g., cheerful, friendly) in postoperative patients but toward negative aspects of mood (e.g., sad, serious) in patients with chronic pain.

Intramuscular meptazinol and morphine in postoperative pain

Meptazinol is an agonist‐antagonist opioid analgesic believed to be unique in its selectivity for µ1 (high affinity) receptors and its cholinergic activity. Our objectives were to determine the relative analgesic potency of intramuscular meptazinol and morphine and to compare mood and side effects in 102 patients with cancer who have postoperative pain. Meptazinol (50, 100, and 200 mg) and morphine (4, 8, and 16 mg) were given for moderate to severe pain in a double‐blind, randomized but balanced, incomplete block design. Serial multiple assessments of pain, relief, mood, and side effects were made. The most precise estimates of relative analgesic potency indicate that meptazinol is equivalent to 10 mg morphine at 120 mg (95% confidence interval 80 to 170 mg) for peak effect and at 175 mg (95% confidence interval 125 to 270 mg) for total effect. Mean (±SE) times to peak effect and to remedication were 0.9 ±0.1 and 3.6 ± 0.2 hours for meptazinol and 1.4 ±0.1 and 4.8 ± 0.4 hours for morphine at equianalgesic peak effects. The percentages of subjects with one or more side effects were 18, 49, and 73 for graded meptazinol doses and 32,49, and 65 for graded morphine doses. Mean numbers of side effects per subject were 0.3, 1.5, and 3.5 for meptazinol and 0.5, 0.7, and 1.7 for morphine. Profiles of side effects differed. Mood improvement and overall satisfaction were dose related and greater for morphine than for meptazinol. Side effects may limit the use of meptazinol in doses that relieve severe postoperative pain.

Appraisal of pain relief mediates the relationship between pain intensity and emotional distress in cancer pain

CHRONIC PAIN PATIENTS AND MEt

Disposition and effects of intravenous (iv) methadone (met) in cancer patients

TAL HEALTH SERYICES.A.H.Lebovits1r2,D.M.Richlin1,S.Rule1,& M.Lefkowitzl,Depts.of 1 Anesthesioloqy & 2Psychiatry,Mt.Sinai Schl.Med.,NY,NY 10029. Aim of 1nvestiqation:Patients with chronic pain often experience severe psychological difficulties,both before and after onset of pain.A retrospective chart review was conducted to assess use of mental health services. Methods:Charts of patients(excludinq terminally ill cancer patientslseen by the Mt.Sinai Pain Management Service in a l-year period were reviewed to determine contacts with mental health professionals,use of psychotropic medication,substance abuse,and selected demographic characteristics. Results:76 patients were reviewed.Mean age was 44.3 yr;53% were female andmedianpain duration was 3.5 yr.The 3 most common chronic pain syndromes were low back pain/sciatica(32%),abdominal pain(l6%),and myofascial pain(l3%).Information available for 65 patients(86%)indicated that 38(58%) had a history of previous contact with a mental health professional,with 17 (45%)of this group initiating contact before pain onset.Women were siqnificantly more likely to report such contact than men(X2=5.27,p-z.O5).Depression was the most common reason for psychological intervention.39 patients (53%)were either currently taking psychotropic medication or had done so in the past;Valium was the most common drug used.20 patients(26%)also reported significant abuse of prescription druqs,street druqs,or alcohol. Conclusions:Current Pain Service practice includes patient screening and exclusion of patients with major psychiatric disorders.Nevertheless,the finding of a nontrivial incidence of previous psychological distress requiring professional attention emphasizes the need for careful evaluation of psychological factors in diagnosis and treatment planning for chronic pain patients.The high incidence of psychotropic drug use and substance abuse further mandates an integral role for mental health professionals in comprehensive pain management.