Meptazinol and morphine in postoperative pain assessed with a new method for onset and duration

A single-tablet fixed-dose combination of racemic ibuprofen/paracetamol in the management of moderate to severe postoperative dental pain in adult and adolescent patients: a multicenter, two-stage, randomized, double-blind, parallel-group, placebo-controlled, factorial study

BACKGROUND

The combination of ibuprofen and paracetamol may confer analgesic benefits over monotherapy with either agent. In a previous study, an ibuprofen/paracetamol combination provided significantly better analgesic efficacy than comparable doses of ibuprofen or paracetamol alone in patients experiencing moderate to severe acute postoperative pain after extraction of impacted third molars.

OBJECTIVE

This study compared the efficacy and tolerability of 3 doses of a single-tablet fixed-dose combination (FDC) of ibuprofen and paracetamol (ibuprofen/paracetamol doses of 100 mg/250 mg, 200 mg/500 mg, and 400 mg/1000 mg) with comparable doses of ibuprofen (200 or 400 mg) monotherapy, paracetamol (500 or 1000 mg) monotherapy, and placebo in the 8 hours after surgical removal of 3 to 4 impacted third molars (stage 1) and with placebo over the next 72 hours (stage 2).

METHODS

This was a multicenter, 2-stage, randomized, double-blind, parallel-group, placebo-controlled, factorial study. Male or female outpatients were eligible for the study if they were aged >or=16 years, were referred for surgical removal of at least 3 impacted third molars (2 of which had to be mandibular impacted molars), and gave written informed consent. In stage 1, patients were randomly assigned to ibuprofen 200 mg, ibuprofen 400 mg, paracetamol 500 mg, paracetamol 1000 mg, FDC ibuprofen 100 mg/paracetamol 250 mg, FDC ibuprofen 200 mg/paracetamol 500 mg, FDC ibuprofen 400 mg/paracetamol 1000 mg, or placebo. In stage 2, patients who had been taking FDC therapy or placebo continued the same treatment, whereas those taking monotherapy received FDC therapy, incorporating the same dose of active monotherapy from stage 1. First-line rescue medication (hydrocodone 7.5 mg and paracetamol 500 mg) was available at any time after dosing; however, in stage 1, any patient who required rescue medication within 60 minutes of receipt of study medication was considered a "dropout" from therapy, and, in stage 2, patients who required >2 doses of first-line rescue medication in a 24-hour period were considered treatment failures. In stage 1, the primary efficacy end points were the sum of pain relief and pain intensity differences over an 8-hour follow-up period (SPRID8) and the pain relief and pain intensity difference scores at each time point (15, 30, 45, 60, 90, 120, 180, 240, 300, 360, 420, and 480 minutes after dosing). Several secondary variables were also measured, including the patient's global assessment of the study medication. The 2-stopwatch method was used for measures of perceptible and meaningful pain relief. In stage 2, the primary efficacy end point was the number of completed 24-hour periods (as 0, 1, 2, or 3) in which the patient required no more than one dose of rescue medication and rated the treatment as "good," "very good," or "excellent." The tolerability of study medications was assessed in relation to the frequency, nature, and severity of adverse events (AEs), as well as their relationship to study medication; vital signs were also measured. AEs were assessed at 8 hours after dosing in stage 1, at 72 hours after dosing in stage 2, and at the follow-up visit (7-10 days after surgery); in addition, patients were instructed to report any AE that occurred between scheduled assessments.

RESULTS

Of 735 patients randomly assigned in stage 1, a total of 715 (97.3%) entered and 678 (92.2%) completed stage 2. Most patients were female (62.6% [460/735]) and white (91.3% [671/735]); the mean (SD) age was 20.3 (3.5) years and the mean weight was 69.7 (15.7) kg. The mean total impaction score was 11.1 (1.4), and the mean baseline pain score on the visual analog scale was 76.9 (12.0). Overall, 422 of 735 patients (57.4%) reported severe pain at baseline and 313 of 735 (42.6%) reported moderate pain. For the primary efficacy end point (SPRID8), FDC ibuprofen 400 mg/paracetamol 1000 mg was significantly more effective than ibuprofen 400 mg (P = 0.02) and paracetamol 1000 mg (P < 0.001) in the immediate postoperative period (stage 1), and FDC ibuprofen 200 mg/paracetamol 500 mg was significantly more effective than ibuprofen 200 mg (P < 0.001) and paracetamol 500 mg (P < 0.001). The FDC ibuprofen 200 mg/paracetamol 500 mg was also significantly more effective than paracetamol 1000 mg (P < 0.001), but failed to reach statistical significance in comparison with ibuprofen 400 mg. Continued postoperative therapy with all 3 FDCs on an as-needed basis was significantly more effective than placebo during the subsequent 72 hours (all, P < 0.001). During stage 1, rescue medication was required by 53 of 73 (72.6%), 29 of 75 (38.7%), 21 of 74 (28.4%), 56 of 76 (73.7%), and 51 of 74 (68.9%) patients in the placebo group and the ibuprofen 200-mg, ibuprofen 400-mg, paracetamol 500-mg, and paracetamol 1000-mg treatment groups, respectively. In the FDC treatment groups, the need for rescue medication included 27 of 71 (38.0%), 40 of 143 (28.0%), and 32 of 149 (21.5%) patients in the ibuprofen 100-mg/paracetamol 250-mg, ibuprofen 200-mg/paracetamol 500-mg, and ibuprofen 400-mg/paracetamol 1000-mg groups, respectively. The rates of treatment-related AEs between the first and second doses of study medication were significantly lower for FDC ibuprofen 400 mg/paracetamol 1000 mg (8/149 patients [5.4%]) than for placebo (14/73 [19.2%]; P < 0.01) and paracetamol 1000 mg (10/74 [13.5%]; P < 0.05); and also lower for FDC ibuprofen 200 mg/paracetamol 500 mg (9/143 [6.3%]) compared with ibuprofen 200 mg (12/75 [16.0%]; P < 0.05) and paracetamol 500 mg (17/76 [22.4%]; P < 0.001).

CONCLUSION

FDC ibuprofen 200 mg/paracetamol 500 mg and ibuprofen 400 mg/paracetamol 1000 mg were significantly more effective in this population than were comparable doses of ibuprofen or paracetamol alone in moderate to severe acute dental pain and were significantly more effective than placebo in providing sustained pain relief.

Comparative sensitivity of stopwatch methodology and conventional pain assessment measures for detecting early response to triptans in migraine: results of a randomized, open-label pilot study

BACKGROUND

The standard measure of efficacy used in migraine trials is a 4-point patient-rated headache pain intensity (HPI) scale. However, it has been suggested that using a stopwatch to measure the time to meaningful pain relief can provide a more precise measurement of treatment response.

OBJECTIVE

This study evaluated the sensitivity of a stopwatch method for detecting meaningful relief of headache pain and the correlation of this method with the HPI scale and a 5-point pain relief scale.

METHODS

In this open-label, parallel-group pilot study, patients were randomized to receive oral eletriptan 40 mg, eletriptan 80 mg, or rizatriptan 10 mg for the treatment of a single acute migraine attack. The effect of study treatment on migraine pain was assessed immediately before dosing and at 0.5, 1, 1.5, 2, 3, and 4 hours after dosing. At each time point, patients recorded the 3 types of pain assessment in a patient diary. HPI was rated using the standard 4-point International Headache Society pain intensity scale (from 0 = no pain to 3 = severe pain). Pain relief was rated on a 5-point pain relief scale (from 4 = no relief to 0 = complete relief). The time to the onset of meaningful pain relief was measured using a stopwatch. At 4 hours after dosing, patients provided a global rating of the overall efficacy of study medication on a 5-point scale (from 0 = poor to 4 = excellent).

RESULTS

Seventy-nine patients participated in the trial (78.5% female; mean [SD] age, 37.7 [9.8] years; 58.2% white). The median times to meaningful pain relief measured by stopwatch were 84, 72, and 93 minutes for eletriptan 40 mg, eletriptan 80 mg, and rizatriptan 10 mg, respectively (log-rank P = 0.029, eletriptan 80 mg vs rizatriptan 10 mg). At 90 minutes (approximating the median time to meaningful pain relief on the stopwatch), headache response rates using HPI scoring (mild to no pain) were 65%, 68%, and 52% in the respective treatment groups, with no significant difference between groups. On the pain relief scale, the corresponding mean (SD) scores at 90 minutes were 1.6 (1.2), 1.4 (1.3), and 2.0 (1.4) (P = NS). The pain relief-defined response (> or = 75% pain relief) at 90 minutes did not differ significantly between the 3 treatment groups (62%, 56%, and 48%). Detection of early improvement (0.5 and 1 hour) was similar with the HPI and pain relief scales.

CONCLUSION

The results of this open-label pilot study suggest the convergent validity of 3 pain-assessment methods in migraine, but indicate that the use of a stopwatch may be a more sensitive method for detecting between-group differences.

Analgesic efficacy of the cyclooxygenase-inhibiting nitric oxide donor AZD3582 in postoperative dental pain: Comparison with naproxen and rofecoxib in two randomized, double-blind, placebo-controlled studies

OBJECTIVE

This study assessed the analgesic efficacy of single doses of 4-(nitrooxy)butyl-(2S)-2-(6-methoxy-2-naphthyl) propanoate (AZD3582) in acute postoperative dental pain after the removal of an impacted mandibular third molar (ie, wisdom tooth).

METHODS

Two randomized, placebo-controlled, double-blind studies were performed. In a dose-finding study, 242 patients were randomized to AZD3582 375, 750, 1500, or 2250 mg (n = 41, 37, 42, and 41, respectively); naproxen 500 mg (n = 39); or placebo (n = 42). In a comparator study, 282 patients were randomized to AZD3582 500 mg (n = 78) or 750 mg (n = 83), rofecoxib 50 mg (n = 80), or placebo (n = 41). Primary outcomes included time to rescue medication, time to pain relief, and mean pain intensity difference (MPID), as well as safety profile. Pain was rated on a visual analog scale.

RESULTS

In the dose-finding study, 52% (126/242) were women; the mean (SD) age was 25.1 (4) years, mean weight was 69.0 kg, and the mean (SD) body mass index (BMI) was 23.7 (3) kg/m2. In the comparator study, 58% (164/282) were women; the mean (SD) age was 27 (6.4) years, mean weight was 71 kg, and mean (SD) BMI was 24.2 (3) kg/m2. In the dose-finding study, the AZD3582 750-, 1500-, and 2250-mg groups were superior to placebo in the primary variables "time to rescue medication (0-8 hours)" (hazard ratios [HRs] [95% CIs], 0.17 [0.07-0.42], P < 0.003; 0.23 [0.11-0.50], P < 0.001; and 0.15 [0.06-0.36], P < 0.001, respectively), "time to meaningful pain relief" (HRs [95% CIs], 3.42 [1.87-6.25], P < 0.003; 2.49 [1.37-4.50], P < 0.003; and 3.07 [1.70-5.55], P < 0.001, respectively), and MPID (analysis of covariance [ANCOVA] least squares mean [LSM] differences [95% CIs], 25.8 [17.3-34.4], P < 0.003; 20.4 [12.1-28.7], P < 0.003; and 29.3 [20.9-37.6], P < 0.001, respectively). AZD3582 and naproxen did not show any statistically significant differences for the 3 primary variables, except that naproxen was superior to the AZD3582 375-mg dose for the variables time to meaningful pain relief (HR difference, 0.48 [95% CI, 0.29-0.78], P < 0.004) and MPID (difference in ANCOVA LSM, -10.2, [95% CI, -18.2 to -2.2], P < 0.012). The median times to meaningful pain relief were 115 minutes for AZD3582 375 mg, 66 minutes for 750 mg, 85 minutes for 1500 mg, 81 minutes for 2250 mg, and 162 minutes for placebo (P = NS, P = 0.003, P < 0.003, and P < 0.001, respectively). The median time to first rescue medication was 144 minutes for placebo, and <50% of the subjects on any of the AZD3582 doses or naproxen took rescue medication within 8 hours after dosing. In the comparator study, AZD3582 750 mg was superior to placebo in "time to rescue medication (0-24 hours)" (HR [95% CI], 0.4 [0.3-0.6], P < 0.001), "time to confirmed perceptible pain relief" (2.1 [1.1-3.8], P = 0.02), and MPID (11.9 [4.2-19.5], P = 0.002). However, inferiority of AZD3582 to rofecoxib for MPID could not be excluded (tolerance limit of 10 mm; P = NS for noninferiority testing). The median times to confirmed perceptible pain relief were 45 minutes for AZD3582 500 mg, 40 minutes for 750 mg, and 37 minutes for rofecoxib. The median times to first rescue medication were 218 minutes for AZD3582 500 mg, 365 minutes for 750 mg, 635 minutes for rofecoxib, and 90 minutes for placebo. Overall, AZD3582 was well tolerated. However, an effect on orthostatic blood pressure could not be excluded because there seemed to be more subjects with dizziness and orthostatic blood pressure reduction who were administered AZD3582 > or =750 mg. The proportions of patients with vertigo and decreased orthostatic blood pressure each group were as follows: AZD3582 500 mg, 6%; AZD3582 750 mg, 12%; rofecoxib, 3%; and placebo, 5%.

CONCLUSIONS

AZD3582 750 mg had similar analgesic efficacy as equimolar doses of naproxen, but noninferiority to rofecoxib was not demonstrated.

Onset of acetaminophen analgesia: comparison of oral and intravenous routes after third molar surgery

BACKGROUND

The purpose of this randomized double-blind study was to compare the efficacy and safety of propacetamol 2 g (an i.v. acetaminophen 1 g formulation) administered as a 2-min bolus injection (n=50) or a 15-min infusion (n=50) with oral acetaminophen 1 g (n=50) or placebo (n=25) for analgesia after third molar surgery in patients with moderate to severe pain after impacted third molar removal.

METHODS

All patients were evaluated for efficacy during the initial 6 h period after treatment administration (T(0)) and for safety during the entire week after T(0).

RESULTS

The onset of analgesia after propacetamol was shorter (3 min for bolus administration, 5 min for 15-min infusion) than after oral acetaminophen (11 min). Active treatments were significantly better for all parameters (pain relief, pain intensity, patient's global evaluation, duration of analgesia) than placebo (P<0.05). Adverse events were more frequent after propacetamol, especially pain at the injection site. Propacetamol bolus resulted in a much higher incidence of local adverse events than the infusion (propacetamol bolus 90% vs propacetamol infusion 52%) with no clinically significant benefits in terms of analgesic efficacy.

CONCLUSION

I.V. propacetamol, administered as a 15-min infusion, is a fast-acting analgesic agent. It is more effective in terms of onset of analgesia than a similar dose of oral acetaminophen.

Inhibitory effect of intrathecal meptazinol on carrageenan-induced thermal hyperalgesia in rats

The effect of meptazinol in the spinal cord on carrageenan-induced hyperalgesia was investigated. The latency of paw withdrawal (PWL) to a thermal stimulus was used as an index of inflammatory hyperalgesia in awake rats. Intrathecal (i.t.) injection of 10 and 100 microg meptazinol markedly increased the PWL of the carrageenan-injected paw (P<0.01). The PWL of the non-injected paw was not detectably affected by the administration of meptazinol at the doses tested. I.t. injection of naloxone (5 microg) or atropine (1 microg) alone exhibited no effect on the PWLs of either the carrageenan-injected or non-injected paw. Pretreatment with naloxone, but not atropine, completely blocked the meptazinol-induced anti-hyperalgesia. These observations suggested that mu opioid receptor rather than muscarinic acetylcholine receptor may be involved in the anti-hyperalgesia of meptazinol in the spinal cord.

A controlled comparative study of ibuprofen arginate versus conventional ibuprofen in the treatment of postoperative dental pain

The analgesic efficacy of an arginine salt of ibuprofen was compared to one of the commercially available forms of conventional ibuprofen in a 500-patient clinical trial in postoperative dental pain. Patients were administered a single dose of ibuprofen arginate (200 mg or 400 mg), conventional ibuprofen (200 mg or 400 mg), orplacebo in this double-blind, randomized, parallel-group trial. Results demonstrated that ibuprofen arginate was a safe and effective analgesia that was superior to conventional ibuprofen in both the amount of pain relief achieved and the time to onset of pain relief. Onset of analgesia, assessed as the median amount of time to achieve meaningful pain relief, was reached after 32 and 31 minutes with ibuprofen arginate 200 and 400 mg, respectively, and 64 and 58 minutes with conventional ibuprofen 200 and 400 mg, respectively (p < 0.05). Patients treated with ibuprofen arginate rated its overall effectiveness higher than those patients treated with conventional ibuprofen. Adverse event profiles were similar across all treatment groups.

A randomized, double-blind, placebo-controlled comparison of the analgesic efficacy, onset of action, and tolerability of ibuprofen arginate and ibuprofen in postoperative dental pain

BACKGROUND

Because of its enhanced pharmacokinetic characteristics, ibuprofen arginate might be expected to provide faster pain relief than standard ibuprofen formulations in patients experiencing acute pain.

OBJECTIVE

This study assessed the analgesic efficacy, speed of onset, and tolerability of ibuprofen arginate compared with a commercially available form of ibuprofen in patients with postoperative dental pain.

METHODS

Patients were randomized to receive ibuprofen arginate 200 or 400 mg, ibuprofen 200 or 400 mg, or placebo in this multicenter, double-blind, double-dummy, parallel-group trial. Patients were observed for 6 hours after administration of a single dose of study medication. A repeated-dose, open-label phase followed. Pain intensity and pain relief were measured using traditional verbal descriptor scales; onset of analgesia was assessed using 2 stopwatches to measure the time to achievement of specific pain relief criteria.

RESULTS

A total of 498 patients (219 men, 279 women; mean age, 21.5 years) participated in this study. Baseline pain was moderate in 388 patients (78%) and severe in 110 patients (22%). Meaningful pain relief was reached after a median of 29 and 28 minutes with ibuprofen arginate 200 and 400 mg, respectively, and after 52 and 44 minutes with ibuprofen 200 and 400 mg, respectively (all, P < 0.05). The percentages of patients who achieved meaningful pain relief within the first hour after treatment were 77.6% and 83.7% for ibuprofen arginate 200 and 400 mg, respectively, 61.0% and 63.0% for ibuprofen 200 and 400 mg, respectively, and 39.8% for placebo. The differences between ibuprofen arginate and ibuprofen were statistically significant (both doses, P < 0.05). Significantly greater numbers of patients achieved meaningful pain relief with ibuprofen arginate 400 mg compared with placebo from 20 minutes through 6 hours and with ibuprofen arginate 200 mg from 30 minutes through 6 hours (P < 0.05). Compared with placebo, a greater number of patients achieved meaningful pain relief with ibuprofen 400 mg from 45 minutes through 6 hours; with ibuprofen 200 mg. the corresponding interval was from I through 6 hours. After the first hour, pain reduction was similar for the similar doses of the 2 ibuprofen preparations. Median remedication times with both doses of ibuprofen arginate were similar to those with both doses of ibuprofen, ranging from 4.0 to 5.2 hours. Adverse-event profiles were similar between the 2 active medications.

CONCLUSIONS

Ibuprofen arginate was effective in this population of patients experiencing moderate to severe pain after surgical extraction of > or = 1 impacted third molar, with 16 to 24 minutes' faster time to meaningful pain relief than with ibuprofen. The 2 formulations had similar tolerability profiles.

Assessing the onset of relief of a treatment for migraine

It is common for clinical trials designed to compare treatments for migraine to incorporate a component for estimating onset. Our objective is to describe a stopwatch method for collecting data on time to meaningful relief and a conceptual framework for describing and analysing the results. The survival distribution of onset is modelled in two parts: the probability that onset does not occur, and the survival distribution conditional on its occurrence. Using data from a clinical trial comparing an active treatment and placebo, we illustrate the method and find that the distributions of onset among those with onset do not differ, but the probabilities that onset occurs are substantially different. We illustrate how the model can be used to help determine how long patients without onset should wait before further intervention, how patients interpret the phrase meaningful relief, and how baseline clinical characteristics affect the onset.

Analgesic efficacy and bioavailability of ketorolac in postoperative pain: a probability analysis

BACKGROUND

The analgesic efficacy and bioavailability of 30 mg intramuscular ketorolac was studied in 24 patients with severe or very severe postoperative pain.

METHODS

Pain and pain relief were determined by a five-point verbal rating scale and data were submitted to a probability analysis. Ketorolac plasma levels were determined by high-performance liquid chromatography.

RESULTS

Two patients chose not to finish the study; 22 patients completed the study achieving at least good pain relief. Of these 22 patients, 13 reached complete pain relief. Ketorolac was rapidly absorbed. Notwithstanding, pain relief increased gradually, showing considerable delay with regard to plasma concentrations. Analysis of the probability-time curves revealed that 25% of the patients obtained moderate pain relief at 7 min after ketorolac administration, 50% at 11 min, 75% at 29 min, and 95% at 60 min. Good pain relief was achieved in 25, 50, and 75% of the patients at 1.1, 1.8, and 2.7 h, respectively. Complete pain relief was achieved in 25% and 50% of the patients at 2.6 h and 3.7 h, respectively. The probability of exhibiting an acceptable pain relief in responsive patients for more than 5 h was 0.97. No serious side effects were detected.

CONCLUSIONS

Results show that 30 mg intramuscular ketorolac is an adequate treatment for postoperative pain in the Mexican population. Therefore, the use of higher doses is not justified. Due to gradual installation of analgesia, administration of additional analgesic medication before 1 h is not recommended.

Membrane toxicity of opioids measured by protozoan motility

The acute toxicity of some opioid drugs cannot solely be explained by a specific interaction with the opioid receptor. The anaesthetic-like membrane effect of 10 opioid agents and the antagonist naloxone was determined and correlated with their hydrophobicity. The inhibitory effect of drugs on protozoan motility was used as a measure of their membrane toxicity, measured by the reduction in swimming speed of Tetrahymena pyriformis using an image analysis system. Hydrophobicity was determined as the n-octanol/water partition coefficient, at pH 7.4, 37 degrees C. Opioid agents dose-dependently reduced the swimming speed of Tetrahymena pyriformis with a wide range of IC50 values. Some weak opioid agents were shown to have high protozoan immobilising potency comparable to quinidine, an agent with known membrane stabilising activity. Norpropoxyphene, the metabolite of dextropropoxyphene, with little affinity for the opioid receptor, also had a high potency. The inhibition of protozoan motility by these opioid agents was not antagonised by the opioid receptor antagonist naloxone; moreover an additive inhibitory action was demonstrated when opioid agents were combined with naloxone. The effect of opioid agents on protozoan motility was closely correlated with their partition coefficient but not with their known affinity for opioid receptors. These results suggest that opioid agents possess differing degrees of membrane depressant action independent from their interaction with the opioid receptor, and have a potential for causing depressant effects on excitable tissues.

Statistical methods for cost-effectiveness analyses

A statistical framework is presented for examining cost and effect data on competing interventions obtained from an RCT or from an observational study. Parameters of the join distribution of costs and effects or a regression function linking costs and effects are used to define cost-effectiveness (c-e) measures. Several new c-e measures are proposed that utilize the linkage between costs and effects on the patient level. These measures reflect perspectives that are different from those of the commonly used measures, such as the ratio of expected cost to expected effect, and they can lead to different relative rankings of the interventions. The cost-effectiveness of interventions are assessed statistically in a two stage procedure that first eliminates clearly inferior interventions. Members of the remaining admissible set are then rank ordered according to a c-e preference measure. Statistical techniques, particularly in the multivariate normal case, are given for several commonly used c-e measures. These techniques provide methods for obtaining confidence intervals, for testing the hypothesis of admissibility and for the equality of interventions, and for ranking interventions. The ideas are illustrated for a hypothetical clinical trial of antipsychotic agents for community-based persons with mental illness.

Statistical evaluation of relationships between analgesic dose and ordered ratings of pain relief over an eight-hour period

Statistical considerations are discussed for the application of alternative methods to a clinical trial involving repeated ordinal ratings and multiple dosage levels of active drugs. Analyses included summary measures traditionally employed in studies of acute pain: sum of pain intensity differences from baseline, total pain relief, and total pain half gone. Estimators and confidence intervals of relative potency are developed for univariate and multivariate situations, using weighted least squares analysis with mean response and variances from Taylor series linearizations. The estimates from these methods are compared to those from traditional methods, such as ordinary least squares regression and Fieller's method for confidence intervals, as well as those from more recent developments, such as generalized estimating equations and sample survey data regression. A double-blind, two-center, randomized clinical trial of acute pain relief comparing placebo with two analgesics, each at two dosage levels, over an 8-hr period serves as an illustrative example for these techniques and comparisons.