Clinical Trials of Evening Primrose Oil and Diabetic Neuropathy.
| Trial | Design | Number R/C | Dose | Duration(mo) | Outcome* |
|---|---|---|---|---|---|
| Jamal & Carmichael,15 | R,DB,PL | 22/22 | 360 mg qd | 6 | Significant improvement |
| 1990 | Symptom scores (−2.1 vs 0.9) | ||||
| Median MCV (1.4 vs −1.4) | |||||
| Peroneal MCV (1.9 vs −0.1) | |||||
| Median CMAP (1.0 vs −0.7) | |||||
| Peroneal CMAP (0.7 vs −0.3) | |||||
| Median (1.8 vs −1.7) | |||||
| Sural SNAP (0.4 vs −1.5) | |||||
| Ankle HT (°C) (−2.3 vs 0.5) | |||||
| Wrist HT (°C) (−0.5 vs 0.02) | |||||
| Not significant | |||||
| Sign scores | |||||
| Ankle, wrist CT (°C) | |||||
| Keen et al,16 1993 | R,DB,PL | 111/84 | 480 mg qd | 12 | Significant improvements |
| Median MCV (2.4 vs −2.1) | |||||
| Peroneal MCV (2.2 vs −1.9) | |||||
| Extensor digitorum brevis CMAP (1.2 vs −0.6) | |||||
| Thenar CMAP (1.4 vs −1.1) | |||||
| Median SNAP (2.4 vs −1.3) | |||||
| Sural SNAP (1.7 vs −1.0) | |||||
| Wrist HT (°C) (0.8 vs −0.4) | |||||
| Wrist CT (°C) (0.8 vs −0.3) | |||||
| Arm tendon reflex (2.9 vs −12.0) | |||||
| Leg tendon reflex (17.7 vs 0.5) | |||||
| Arm sensation (6.9 vs −7.3) | |||||
| Leg sensation (15.0 vs −8.4) | |||||
| Arm muscle strength (4.9 vs −7.4) | |||||
| Not significant | |||||
| Ankle HT and CT (°C) | |||||
| Leg muscle strength | |||||
| Purewal et al,17 1997 | R,DB,PL | 51/51 | 480 mg qd | 12 | Not significant |
| Vibratory threshold at hallux |
R=randomized, DB=double-blind, PL = placebo-controlled, C=number of patients completing trial, MCV=median conduction velocity, CMAP=compound muscle action potential, SNAP=sensory nerve action potential, HT = heat threshold, CT=cold threshold.
* Numbers in parenthesis indicate significant difference compared with placebo in favor of evening primrose oil.