1. Abuse Potential of Morphine/Dextromethorphan Combinations
Donald R Jasinski, MD 
Journal of Pain and Symptom Management 
Volume 19, Issue 1, Pages (January 2000)
DOI: /S (99)00127-X

2. Fig. 1
Effect of dextromethorphan on the responses to morphine and placebo. In each graph, the squares represent the mean of the response on measures of euphoria to morphine and placebo in the presence of placebo. The circles represent the mean response to placebo and morphine in the presence of dextromethorphan. The error bars represent one-half the least significant difference as calculated from the error mean square and the analysis of variance. Statistical significance is indicated by lack of overlap of the error bars
Journal of Pain and Symptom Management  , 26-30DOI: ( /S (99)00127-X)

3. Fig. 2
Effect of dextromethorphan on naloxone-precipitated withdrawal. Each response represents the mean area under the curve score, with the error bars representing one-half the least significant difference. Each square represents the mean response to withdrawal precipitated by naloxone in the presence of placebo and doses of dextromethorphan. Statistical significance is indicated by lack of overlap of the error bars
Journal of Pain and Symptom Management  , 26-30DOI: ( /S (99)00127-X)

4. Fig. 3
Slope changes over time for the response of minute volume to increased CO2. The squares represent the comparison of placebo to morphine in the presence of dextromethorphan/placebo at 0 h (predrug) and at 2, 4, and 6 h after dosing. The circles represent the response to morphine and placebo in the presence of dextromethorphan. Error bars represent one-half of the least significant difference. Statistical significance is indicated by lack of overlap of the error bars
Journal of Pain and Symptom Management  , 26-30DOI: ( /S (99)00127-X)