***TASK*** the task is to summarize an input biomedical literature in six sentences 
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    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: UNLABELLED Sex differences in analgesic responses to mu opioid agonists have been reported , although the direction of these differences varies across studies . To further characterize sex differences in responses to mu opioids , the analgesic effects of intravenous morphine ( 0.08 mg/kg ) were determined in healthy women ( n = 61 ) and men ( n = 39 ) by using 3 experimental pain models , heat pain , pressure pain , and ischemic pain . Each pain procedure was conducted before and after double-blind administration of both morphine and saline , which occurred on separate days in counterbalanced order . Although morphine produced significant analgesic effects for all pain stimuli , no significant sex differences in morphine analgesia emerged . However , morphine attenuated cardiovascular reactivity to the ischemic pain task in men but not women , and women reported significantly more drug-related adverse effects than men . These findings are in contrast with some recent clinical and experimental results suggesting more robust analgesic response to mu opioids among women compared to men , although the data indicate that sex differences in non-analgesic effects of morphine were present . These results suggest that sex differences in responses to  morphine  might depend on the pain model and /or drug dose as well as the specific end point assessed . PERSPECTIVE This study examines morphine responses in women and men by using laboratory pain measures . The results indicate no sex differences in analgesia , but women reported greater side effects , and morphine attenuated cardiovascular responses more strongly among men than women . These results add to the literature regarding sex differences in response to opioids Background There is little agreement about a differential response of men and women to opioid analgesics . Some experimental and clinical studies have shown that women have a better response to opioids , others have found no difference , and still others have found opioids to be more effective analgesics for men than women . Objectives To assess sex differences in analgesic response to morphine and incidence of adverse events in patients receiving a dose of 0.1 mg intravenous morphine/kg .  Methods Secondary analysis of the control arms of 6 r and omized clinical trials that compared 0.1 mg/kg intravenous morphine with other opioids or other doses of morphine in patients aged 21 to 65 with acute pain . The setting was an academic medical center Emergency Department serving primarily Latino and African-American patients .  Change in self-reported pain intensity from baseline to 30 minutes postbaseline on a vali date d and reproducible 11-point numerical rating scale and count of adverse events were the primary outcomes . Results The sample consisted of 211 women and 144 men . The mean change in pain from baseline to 30 minutes postbaseline was 3.7 in women , 3.6 men ( difference=0.04 ; 95 % confidence interval : −0.52 , 0.60 ) . In women without nausea before administration of morphine  , the incidence of adverse events was 18.3 % versus 10.7 % in men without initial nausea ( difference=7.6 % ; 95 % confidence interval : −2.0 , 17.2 ) . Discussion Men and women presenting to the Emergency Department did not have a differential response to a single weight-based dose of morphine for alleviation of acute pain . Women without baseline nausea had more adverse events than men The aim of the present study was to examine the possible role of personality traits , in accordance with Cloninger 's theory , and gender , in the variability of responsiveness to opioids . Specifically , it was intended to test whether or not the three personality dimensions - harm avoidance ( HA ) , reward dependence ( RD ) and novelty seeking ( NS ) - as suggested by Cloninger , can predict inter-personal differences in responsiveness to morphine after exposure to experimental cold pain . Thirty-four healthy volunteers ( 15 females , 19 males ) were given the cold pressor test ( CPT ) .  Pain threshold , tolerance , and magnitude ( VAS ) were measured before and after ( six measures , 30 min apart ) the administration of either 0.5 mg/kg oral morphine sulphate ( n=21 ) or 0.33 mg/kg oral active placebo ( diphenhydramine ) ( n=13 ) in a r and omized , double blind design . Assessment of the three personality traits , according to Cloninger 's Tridimensional Personality Question naire , was performed before the CPT . A high HA score ( but not RD , NS , or baseline values of the three pain parameters ) predicted a significantly larger pain relief following the administration of morphine sulphate ( but not of the placebo ) . Women exhibited a larger response in response to both treatments , as indicated by a significantly increased threshold and tolerance following morphine sulphate as well as significantly increased tolerance and decreased magnitude following placebo administration . The present study confirms the existence of individual differences in response to analgesic treatment . It suggests that high HA personality trait is associated with better responsiveness to morphine treatment , and that females respond better than men to both morphine and placebo Background : Sex-related differences in the perception of pain and susceptibility to opioids remain a matter of debate . Intravenous morphine titration used to obtain pain relief in the immediate postoperative period is a unique clinical model for assessing the effect of sex on reported pain . Because of the wide variation in dose requirements for pain management , the authors conducted a prospect i ve study in a large population and also assessed the effect of aging . Methods : Intravenous morphine titration was administered as a bolus of 2 ( body weight ≪ 60 kg ) or 3 mg ( body weight > 60 kg ) during the immediate postoperative period . The interval between each bolus was 5 min . The visual analog pain scale ( VAS ) threshold required to administer morphine was 30 , and pain relief was defined as a VAS score of 30 or less . Data are expressed as mean ± SD . Results : Data from 4,317 patients were analyzed ; 54 % of the patients were male , and 46 % were female . The mean morphine dose required to obtain pain relief was 11.9 ± 6.8 mg or 0.173 ± 0.103 mg/kg . Women had a higher initial VAS score ( 74 ± 19 vs. 71 ± 19 ; P < 0.001 ) and required a greater dose of morphine ( 0.183 ± 0.111 vs. 0.165 ± 0.095 mg/kg ; P < 0.001 ) . In contrast , no significant difference was noted in elderly ( aged > 75 yr ) patients ( 0.163 ± 0.083 vs. 0.157 ± 0.085 mg/kg ) . Conclusion : Women experienced more severe postoperative pain and required a greater dose ( + 11 % ) of morphine than men in the immediate postoperative period . This sex-related difference disappeared in elderly patients BACKGROUND Postoperative pain is one of the most common therapeutic problems in hospitals . Patient-controlled analgesia has gained popularity over the last decade in dealing with this problem . The goal of this article is to examine the effect of PCA in patients who underwent spinal fusion and to measure its effect on the different sexes and age groups . METHODS Two hundred thirty-seven patients who underwent spinal fusion for lumbar instability at our institution comprise this study . All patients received PCA in a certain protocol . Pain was measured according to the VAS , and any complications due to the use of PCA were recorded . RESULTS Patient-controlled analgesia reduced the VAS in all age groups . Reduction in VAS was higher in the age group of 60 years or more . No significant differences in VAS reduction were noted between males and females . In 40 % of our patients , complications were recorded . Eight percent reported more than 1 complication . However , these complications were nonfatal , and all patients responded well to conservative treatment . On termination of the study , most patients ( 213/237 ) were satisfied with the PCA procedure for reducing their pain . CONCLUSION We conclude that PCA is an effective and safe method with high satisfaction rate in postoperative pain control in patients who undergo spinal fusion The purpose of this prospect i ve clinical trial was to investigate the analgesic efficacy of three oral medication groups on postoperative endodontic pain in male and female dental patients , with an emphasis on analgesic differences between the sexes . Forty-three patients were administered ibuprofen 600 mg , placebo , or pentazocine 50 mg/0.5 mg naloxone in a r and omized , double-blinded manner . Beginning immediately after endodontic treatment , patients took the assigned medication every 6 hours for 24 hours and recorded their degree of discomfort on a 100-mm visual analog scale . Statistical analysis of the data showed that ibuprofen 600 mg provided statistically significantly greater analgesia than placebo at 6 and 12 hours ( P = 0.0014 and 0.0024 ) , and pentazocine/naloxone provided statistically significantly greater analgesia than placebo at 12 hours ( P = 0.0084 ) . Sex-dependent differences were noted within the pentazocine/naloxone group , which showed significantly greater analgesia in females compared with males ( P = 0.007 ) In recent studies we demonstrated that the analgesic effect of the kappa-like opioids is significantly greater in women , that low dose nalbuphine ( 5 mg ) produces profound anti-analgesia ( i.e. enhances pain ) in men , and that addition of a low dose of the non-selective opioid receptor antagonist naloxone ( 0.4 mg ) to nalbuphine ( 5 mg ) abolishes the sex difference and results in significantly enhanced analgesia in both sexes . To further delineate the dose-dependent analgesic and anti-analgesic effects of nalbuphine , the present study evaluated the effect of a lower dose of nalbuphine ( 2.5 mg ) , with and without naloxone , on  dental postoperative pain .  In women , nalbuphine alone induced modest , short duration analgesia , which was antagonized rather than enhanced by the addition of naloxone ( 0.4 mg ) . In men , this dose of nalbuphine alone did not produce analgesia or anti-analgesia , and naloxone ( 0.4 mg ) did not alter the response to nalbuphine . Thus , the anti-analgesic effect of nalbuphine , present in both sexes at the 5 mg dose disappears at the lower dose of nalbuphine . In addition , the mild analgesia in women produced by this lower dose of nalbuphine is antagonized by naloxone Background : Accumulating evidence suggests that there are sex differences in analgesic responses to opioid agonists . Several studies using an oral surgery pain model have reported more robust analgesia to κ-agonist – antagonists ( e.g. , pentazocine , nalbuphine , butorphanol ) among women than among men . However , evidence of sex differences in κ-agonist – antagonist effects from studies of experimentally induced pain in humans is lacking . Methods : Therefore , the analgesic effects of intravenous pentazocine ( 0.5 mg/kg ) were determined in healthy women ( n = 41 ) and men ( n = 38 ) using three experimental pain models : heat pain , pressure pain , and ischemic pain . Each pain procedure was conducted before and after double-blind administration of both pentazocine and saline , which occurred on separate days in counterbalanced order . Results : Compared with saline , pentazocine produced significant analgesic responses for all pain stimuli . However , no sex differences in pentazocine analgesia emerged . Effect sizes for the sex differences were computed ; the magnitude of effects was small , and an equal number of measures showed greater analgesia in men than in women . Also , analgesic responses were not highly correlated across pain modalities , suggesting that different mechanisms may underlie analgesia for disparate types of pain . Conclusions : These findings indicate significant analgesic responses  to pentazocine in both men and women across multiple experimental pain assays , and the absence of sex differences contrasts with previous data from the oral surgery model . The most likely explanation for the discrepancy in results is that of differences in the pain assays . These findings are important because they suggest that sex differences in opioid analgesia may be specific to certain types of pain & NA ; The dose of opioid prescribed for postoperative pain relief has traditionally been based on the weight of the patient . Although a reduction in dose is often suggested for elderly patients over 70 years of age , age‐related alterations to dose are generally not considered for younger patients . The records of 1010 patients , under 70 years old , prescribed morphine via patient‐controlled analgesia ( PCA ) after major operations were examined to see what factors might best predict the amount of morphine used in the first 24 h after surgery . Factors included were age , sex , weight , operative site , verbal numeric pain score ( at rest and on movement ) and a nausea/vomiting score . In a subgroup of 78 of these patients , the effects of intraoperative and recovery room doses of opioid ( ‘ clinical ’ loading dose ) were analysed . Although the interpatient variability in PCA morphine doses was large ( differences of up to 10‐fold in each age group ) , the best predictor of PCA morphine requirement in the first 24 h after surgery ( the amount required in the 24 h after the initial loading dose ) was the age of the patient . An estimate of these requirements for patients over the age of 20 years can be obtained from the formula : average first 24 h morphine requirement ( mg ) = 100 − age . PCA allows patients the flexibility to titrate their own opioid dose ; if conventional analgesic regimens are to become more effective , they too need to allow for the wide interpatient variation in dose requirements . Although previous studies have noted a correlation between patient age and the 
    Output:
    
Sex differences exist in morphine-induced analgesia in both experimental pain studies and clinical PCA studies , with greater morphine efficacy in women .