Table 1.
list of studies included in one or more of the comparisons in the meta-analysis. DM = dextromethorphan, GA = general anesthesia, IM = intramuscular, IV = intravenous, mg/kg = milligrams per kilogram, mg/ml = milligrams per milliliter, NCA = nurse controlled analgesia (doses dependent on patient request and nurse administration on a PRN schedule), PACU = post-anesthesia care unit,PCA = patient controlled analgesia, PCEA = patient controlled epidural analgesia, PO = per os, POD = postoperative day, PRN = pro re nata (as needed), pts = patients.
| Study | Quality Score | Dextromethorphan pts | Control pts | Dextromethorphan dosing | Dextromethorphan dose timing | Surgery type | Anesthesia type | Comparisons tracked | PRN analgesic tracked | Tracked side effects | Comments |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Entezary 2013 (9) | 3 | 54 | 58 | 1 mg/kg PO | Night before surgery | Knee arthroscopy | Spinal | Pain 1, 4h Total opioid 24h | Morphine NCA | Yes | |
| Suski 2010 (10) | 6 | 30 | 30 | 30 or 45 mg PO (weight based) ×4 | 1 hr pre-op and at 8, 20, and 32 hrs post-op | Scoliosis repair | General | Pain 1, 4/6, 24h Total opioid 24h | Morphine IV NCA | Yes | |
| Mahmoodzadeh 2009 (11) | 6 | 23 (in 45 group) 24 (in 90 group) | 22 | 45 or 90 mg PO | 2 hrs pre-op | Open chole | General | Pain 1, 6, 24h Total opioid 24h | Morphine IV NCA | No | Used 90 mg group for comparison |
| Chau-In 2007 (12) | 7 | 50 | 48 | 30 mg PO ×4 | 60 mins pre-op and 3 doses over first 24 hrs post-op | Total abdominal hysterectomy | General | Pain 1, 6, 24h Total opioid 24h | Morphine IV PCA | No | |
| Lu 2006 (13) | 6 | 20 DM 20 DM + ketorolac | 20 control 20 ketorolac | 40 mg IM | 30 mins pre-op | Vaginal hysterectomy | General | Pain 1, 4, 24h | Morphine IV PCA | Yes | Performed ketorolac and non-ketorolac comparisons |
| Yeh 2005 (14) | 4 | 30 DM plus epidural | 30 GA plus epidural; 30 GA only | 40 mg IM | 30 mins pre-op | Colon surgery | General + epidural | Pain 1, 4, 24h | 0.2% ropivacaine and 0.1 mg/mL morphine PCEA | Yes | Excluded GA only group as no direct DM comparison |
| Wu 2005 (15) | 5 | 25 DM 25 DM + lidocaine IV | 25 control 25 lidocaine IV | 40 mg IM | 30 mins pre-op | Lap chole | General | Pain 1, 4, 24h Total opioid 48h | Meperidine IM NCA | Yes | Performed lidocaine and non-lidocaine comparisons |
| Yeh 2004 (16) | 5 | 20 DM 20 DM + tenoxicam | 22 control 21 tenoxicam | 40 mg IM | 30 mins pre-op | Lap chole | General | Pain 1,4, 24h Total opioid 48h | Meperidine IM NCA | Yes | Performed tenoxicam and non-tenoxicam comparisons |
| Weinbroum 2004 (17) | 7 | 29 DM + PCA 28 DM + PCEA | 27 PCA 29 PCEA | 90 mg PO | 90 mins pre-op | Bone tumor resection | General or general + epidural | Pain 6, 24h | PCEA (ropivacaine 3.2 mg plus fentanyl 8 mcg/dose) or PCA (morphine 2mg/dose) only in PACU, then diclofenac | Yes | PCA only used in PACU so no 24h opioid comparison |
| Weinbroum 2003 (18) | 6 | 29 | 27 | 90 mg PO ×3 | 90 mins pre-op and on POD 1 and 2 | Bone tumor resection | General + epidural | Pain 1, 6, 24h | PCEA (1.6 mg ropivacaine plus 4 mcg/mL fentanyl) continuous and by demand | Yes | |
| Weinbroum 2002a (19) | 6 | 25 (in 60 group) 23 (in 90 group) | 24 | 60 or 90 mg PO ×3 | 90 mins pre-op and on POD1 and 2 | Bone tumor resection | General | Pain 1, 24h Total opioid 24h | Morphine IV PCA | Yes | Used 90mg group for comparison |
| Weinbroum 2002b (20) | 6 | 18 DM + epidural 20 DM + GA | 17 epidural 20 GA | 90 mg PO | 90 mins pre-op | Hernia repair or knee arthroscopy | General or epidural | Pain 1, 4/6h | Morphine IV PCA for 2 hours then diclofenac | Yes | Compared both epidural and GA groups |
| Weinbroum 2001 (21) | 6 | 16 (in 60 group) 17 (in 90 group) | 20 | 60 or 90 mg PO | 90 mins pre-op | Hernia repair or knee arthroscopy | Epidural | Pain 1, 6h | Morphine IV PCA in PACU and diclofenac at home | Yes | Used 90 mg group for comparisons as this was used in all the group's further studies |
| Helmy 2001 (22) | 5 | 20 (pre) 20 (post) | 20 | 120 mg IM | 30 mins before incision or 30 mins before end of surgery | Upper abdominal surgery | General | Total opioid 24h | Meperidine IV PCA | Yes | Excluded post group |
| Wadhwa 2001 (23) | 7 | 22 | 34 | 200 mg PO ×3 | 120 mins pre-op and 8 and 16 hrs post-op | Knee replacement or reconstruction | General | Total opioid 24h | Morphine IV PCA | Yes | |
| Liu 2000 (24) | 3 | 30 | 30 | 40 mg IM | 30 mins pre-op | Hemorrhoidectomy | Local | Total opioid 48h | Meperidine IM NCA | Yes | |
| Wu 2000 (25) | 3 | 15 (in 10 group) 15 (in 20 group) 15 (in 40 group) | 15 | 10, 20, or 40 mg IM | 30 mins pre-op | Upper abdominal surgery | General | Pain 1,4, 24h Total opioid 24h | Morphine IV PCA | Yes | Used 40 mg group for comparison as this was used in all the group's further studies |
| Wong 1999 (26) | 3 | 30 | 30 | 40 mg IM | 30 mins pre-op | Modified radical mastectomy | General | Total opioid 48h | Meperidine IM NCA | Yes | |
| Wu 1999 (27) | 2 | 30 (given pre) 30 (given intra) | 30 | 40 mg IM | Just prior to incision or intraoperative | Lap chole | General | Total opioid 48h | Meperidine IM NCA | Yes | Excluded intraoperative group |
| Grace 1998 (28) | 5 | 18 | 19 | 60 mg PO ×2 | Night before and 1 hour pre-op | Laparotomy | General | Total opioid 48h | Morphine IV PCA | No | |
| Kawamata 1998 (29) | 5 | 12 (in 30 group) 12 (in 45 group) | 12 | 30 or 45 mg PO | 60 mins pre-op | Tonsillectomy | General | Pain 24h | Diclofenac PO at home | Yes | Used 45 mg group for comparison |