***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background Gabapentin is an antiepileptic drug used in a variety of chronic pain conditions . Increasing numbers of r and omized trials indicate that gabapentin is effective as a postoperative analgesic . This procedure-specific systematic review aims to analyse the 24-hour postoperative effect of gabapentin on acute pain in adults . Methods Medline , The Cochrane Library and Google Scholar were search ed for double-blind r and omized placebo controlled trials of gabapentin for postoperative pain relief compared with placebo , in adults undergoing a surgical procedure . Qualitative analysis of postoperative effectiveness was evaluated by assessment of significant difference ( P < 0.05 ) in pain relief using consumption of supplemental analgesic and pain scores between study groups . Quantitative analyses of combined data from similar procedures , were performed by calculating the weighted mean difference ( WMD ) of 24-hour cumulated opioid requirements , and the WMD for visual analogue scale ( VAS ) pain , ( early ( 6 h ) and late ( 24 h ) postoperatively ) , between study groups . Side-effects ( nausea , vomiting , dizziness and sedation ) were extracted for calculation of their relative risk ( RR ) . Results Twenty-three trials with 1529 patients were included . In 12 of 16 studies with data on postoperative opioid requirement , the reported 24-hour opioid consumption was significantly reduced with gabapentin . Quantitative analysis of five trials in abdominal hysterectomy showed a significant reduction in morphine consumption ( WMD – 13 mg , 95 % confidence interval ( CI ) -19 to -8 mg ) , and in early pain scores at rest ( WMD – 11 mm on the VAS , 95 % CI -12 to -2 mm ) and during activity ( WMD -8 mm on the VAS ; 95 % CI -13 to -3 mm ) , favouring gabapentin . In spinal surgery , ( 4 trials ) , analyses demonstrated a significant reduction in morphine consumption ( WMD of – 31 mg ( 95%CI – 53 to -10 mg ) and pain scores , early ( WMD – 17 mm on the VAS ; 95 % CI -31 to -3 mm ) and late ( WMD -12 mm on the VAS ; 95 % CI -23 to -1 mm ) also favouring gabapentin  treatment . Nausea was improved with gabapentin in abdominal hysterectomy ( RR 0.7 ; 95 % CI 0.5 to 0.9 ) . Other side-effects were unaffected . Conclusion Perioperative use of gabapentin has a significant 24-hour opioid sparing effect and improves pain score for both abdominal hysterectomy and spinal surgery .  Nausea may be reduced in abdominal hysterectomy Pregabalin is a gamma-amino-butyric acid analog shown to be effective in several models of neuropathic pain , incisional injury , and inflammatory injury . In this review , the role of pregabalin in acute postoperative pain and in chronic pain syndromes has been discussed . Multimodal perioperative analgesia with the use of gabapentinoids has become common . Based on available evidence from r and omized controlled trials and meta- analysis , the perioperative administration of pregabalin reduces opioid consumption and opioid-related adverse effects in the first 24 h following surgery . Postoperative pain intensity is however not consistently reduced by pregabalin . Adverse effects like visual disturbance , sedation , dizziness , and headache are associated with higher doses . The advantage of the perioperative use of pregabalin is so far limited to laparoscopic , gynecological , and daycare surgeries which are not very painful . The role of the perioperative administration of pregabalin in preventing chronic pain following surgery , its efficacy in more painful surgeries and surgeries done under regional anesthesia , and the optimal dosage and duration of perioperative pregabalin need to be studied . The efficacy  of pregabalin in  chronic pain conditions like  painful diabetic neuropathy , postherpetic neuralgia , central neuropathic pain  , and fibromyalgia has been demonstrated Background : A r and omized , double‐blind , placebo‐controlled single oral dose study was done in order to examine whether codeine has an additive analgesic effect to that of paracetamol for moderate and strong postoperative pain after abdominal surgery . The maximum recommended single dose of paracetamol 1000 mg ( Paracet ® ) was compared with a combination of a submnximal dose of paracetamol 800 mg plus codeine 60 mg ( Paralgin forte ® ) and placebo for pain relief  after Caesarean section in 125 patients Blinding embodies a rich history spanning over two centuries . Most research ers worldwide underst and blinding terminology , but confusion lurks beyond a general comprehension . Terms such as single blind , double blind , and triple blind mean different things to different people . Moreover , many medical research ers confuse blinding with allocation concealment . Such confusion indicates misunderst and ings of both . The term blinding refers to keeping trial participants , investigators ( usually health-care providers ) , or assessors ( those collecting outcome data ) unaware of the assigned intervention , so that they will not be influenced by that knowledge . Blinding usually reduces differential assessment of outcomes ( information bias ) , but can also improve compliance and retention of trial participants while reducing biased supplemental care or treatment ( sometimes called co-intervention ) . Many investigators and readers naïvely consider a r and omised trial as high quality simply because it is double blind , as if double-blinding is the sine qua non of a r and omised controlled trial . Although double blinding ( blinding investigators , participants , and outcome assessors ) indicates a strong design , trials that are not double blinded should not automatically be deemed inferior . Rather than solely relying on terminology like double blinding , research ers should explicitly state who was blinded , and how . We recommend placing greater credence in results when investigators at least blind outcome assessment s , except with objective outcomes , such as death , which leave little room for bias . If investigators properly report their blinding efforts , readers can judge them . Unfortunately , many articles do not contain proper reporting . If an article cl aims blinding without any accompanying clarification , readers should remain sceptical about its effect on bias reduction SUMMARY In a double-blind trial three dosage strengths of piritramide , 5 , 10 and 20 mg , were compared with morphine 15 mg in the treatment of  postoperative pain . Pain intensity was assessed by the patient , and pain relief and side effects by a nurse-assessor . A iog-dose response relationship was established for piritramide . Piritramide 20 mg was shown to be equivalent to morphine 15 mg in analgesic effect . From this and previous studies of piritramide , it appears that piritramide has a greater hypnotic effect than an equi-analgesic dose of morphine , but that it has a lesser incidence of other side effects , particularly nausea and vomiting , and hypotensive effects .  Piritramide is indicated as a suitable analgesic for postoperative pain relief STUDY OBJECTIVE The aim of this study was to compare , by a r and omized double-blind method , morphine ( M ) and fentanyl ( F ) in a prehospital setting . METHODS Consecutive patients with severe , acute pain defined as a visual analog scale score ( VASS ) of 60/100 or higher were included . The M group received an initial intravenous M injection of 0.1 mg/kg then of 3 mg every 5 minutes . The F group received an initial intravenous F injection of 1 microg/kg then of 30 microg every 5 minutes . The goal of analgesia was a VASS of 30/100 or lower . The end point was the VASS measured 30 minutes after initial administration ( VAS [ T30 ] ) . RESULTS There were 26 patients included in the M group and 28 in the F group .  Initial VASS(T0 ) and VASS(T30 ) , mean ( 95 % CI ) , were 83 ( 78 - 88 ) and 40 ( 28 - 52 ) in the M group and 77 ( 72 - 82 ) and 35 ( 27 - 43 ) in the F group ( P = NS ) . Sixty-two percent of patients in the M group described analgesia as excellent or good vs 76 % of those in the F group who did ( P = NS ) . There were no differences in the incidence of side effects in the 2 groups . CONCLUSION This study demonstrates that M and F were comparable in treating severe , acute pain in a prehospital setting during the first 30 minutes in spontaneous breathing patients BACKGROUND Nalbuphine , a mixed agonist-antagonist opioid , has a potential to attenuate the mu-opioid effects and to enhance the kappa-opioid effects . However , when morphine and nalbuphine are mixed together , the clinical interactions in different combining ratios on analgesic effect and adverse events are unknown . METHODS This r and omized , double-blind controlled study investigated five different combining ratios of morphine and nalbuphine in 311 patients undergoing gynaecologic operations . The concentrations [ morphine ( mg ml(-1))]/[nalbuphine ( mg ml(-1 ) ) ] were 1/0 in Group 1 , 0.75/0.25 ( ratio 1:3 ) in Group 2 , 0.5/0.5 ( ratio 1:1 ) in Group 3 , 0.25/0.75 ( ratio 3:1 ) in Group 4 , and 0/1 in Group 5 .  Patient-controlled analgesia ( PCA ) requirement , postoperative pain , and adverse events were evaluated throughout the postoperative 24 h period . RESULTS Twenty-four hour PCA requirements were similar among the five groups . Verbal rating scores for pain were statistically higher in Groups 2 and 4 than in Group 3 . The incidences of pruritus were higher in Group 1 ( 15.6 % ) than in Group 2 ( 6.2 % ) , Group 3 ( 3.4 % ) , Group 4 ( 1.6 % ) , and Group 5 ( 0 % ) . The incidences and severity of dizziness , nausea , and vomiting were not significantly different . CONCLUSIONS The interaction between morphine and nalbuphine in PCA admixture on analgesia is additive . Combinations of morphine and nalbuphine in PCA can decrease the incidence of pruritus , and the antipruritus effect is ratio-dependent . This may provide a novel combination strategy of opioid agonist and agonist-antagonist for postoperative pain management after gynaecologic surgery Meptazinol , m-(3-ethyl-1-methyl-hexahydro-1-H-azepin-3-yl ) phenol hydrochloride is a central ly active opioid analgesic with a specificity for the mu-1 receptor . It has been reported to lack many of the side effects commonly observed with morphine and morphinelike drugs in man . The objective of this study was to assess the analgesic efficacy and safety of meptazinol ( 50 mg and 100 mg ) relative to morphine ( 5 mg and 10 mg ) when administered intramuscularly for the treatment of postoperative pain . In addition , a new clinical method for measuring onset and duration and a statistical technique for evaluating the study data are presented . One hundred and seventeen patients were evaluated for 6 hours in a r and omized double blind , single dose , parallel-groups trial . Estimates of relative potency for hourly pain and relief parameters , and the summary variables sum of pain intensity differences ( SPID ) and total pain relief ( TOTPAR ) were performed . The estimate of relative potency of meptazinol to morphine for pain relief was 0.19 at 1/2 hour ( i.e. 100 mg of meptazinol was approximately equivalent to 20 mg of morphine ) . Thereafter , there was a rapid decline of efficacy for meptazinol , with a relative potency estimate of 0.12 at 1 hour and 0.06 at 2 hours . The distribution functions for several time related events were estimated including time to onset , duration and time to remedication . The two drugs had approximately equal onset , but meptazinol had significantly shorter duration . More patients on meptazinol required remedication with a rescue analgesic and at an earlier time than patients on morphine . ( ABSTRACT TRUNCATED AT 250 WORDS Background Following publication of the PRISMA statement , the UK Centre for Review s and Dissemination ( CRD ) at the University of York in Engl and began to develop an international prospect i ve register of systematic review s with health-related outcomes . The objectives were to reduce unplanned duplication of review s and provide transparency in the review process , with the aim of minimizing reporting bias . Methods An international advisory group was formed and a consultation undertaken to establish the key items necessary for inclusion in the register and to gather views on various aspects of functionality . This article describes the development of the register , now called PROSPERO , and the process of registration . Results PROSPERO offers free registration and free public access to a unique prospect i ve register of systematic review s across all areas of health from all around the world . The dedicated web-based interface is electronically search able and available to all prospect i ve registrants . At the moment , inclusion in PROSPERO is restricted to systematic review s of the effects of interventions and strategies to prevent , diagnose , treat , and monitor health conditions , for which there is a health-related outcome .Ideally , registration should take place before the research ers have started formal screening against inclusion criteria but review s are eligible as long as they have not progressed beyond the point of completing data extraction .The required data set captures the key attributes of review design as well as the administrative details necessary for registration .Su bmi t 
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There was some evidence that the method ological limitations of the trials explained some of the residual heterogeneity .
Type of surgery was not independently associated with analgesic efficacy .
Assuming a fixed baseline risk of 50 mg ( in order of efficacy ) , gabapentin , acetaminophen , & agr;2-agonists , nonsteroidal anti-inflammatory drugs and cyclooxygenase-2 inhibitors , pregabalin , tramadol , magnesium , and lidocaine demonstrated moderate clinical ly significant reductions ( > 10 mg ) .
We could not exclude a moderate clinical ly significant effect with ketamine .
Dexamethasone demonstrated a small clinical benefit ( > 5 mg ) .
: We empirically identified baseline morphine consumption as the major source of heterogeneity in meta-analyses of adjuvant analgesics across all surgical interventions .
Moreover , we have utilized these findings to present a novel method of reporting and an amended method of graphically displaying effect estimates , which both reduces confounding from variable baseline risk in included trials and is able to adjust for other clinical and method ological confounding variables .