Table 4 The effect of vitamin C on opioid analgesic requirements

Placebo controlled RCT

 Laparoscopic colectomy—for colon cancer [97]

i. Placebo (N = 48)

i. 16 mg morphine at 2 h, frequency of rescue analgesia: 1.4

ii. 50 mg IV vitamin C/kg body weight (N = 49) prior to surgery

ii. 14 mg morphine at 2 h*, frequency of rescue analgesia: 0.8*, ↓ pain at 2, 6, 24 h (NRS)*

 Uvulopalatopharyngoplasty with tonsillectomy [98]

i. Placebo (N = 20)

i. 46 mg pethidine, first dose at 3 h, number of requests: 1.3

ii. 3 g IV vitamin C (N = 20) 30 min into surgery

ii. 6 mg pethidine*, first dose at 12 h*, number of requests: 0.2*,

↓ pain at 6, 12, 24 h (VAS)*

 Cholecystectomy [99]

i. Placebo (N = 40)

i. 23 mg morphine

ii. 2 g oral vitamin C (N = 40) prior to surgery

ii. 16 mg morphine* (at 24 h follow up)

Uncontrolled prospective

 Range of malignancies [96]

2 g oral vitamin C (N = 17) for 3 days

Before: 360 mg/day opioids

After: 390 mg/day opioids

Controlled retrospective

 Terminal cancer [82]

i. Control (N = 19)

i. 79% required narcotics

ii. 0.5–3 g/day oral vitamin C (N = 6)

ii. 50% required narcotics

iii. 5–30 g/day oral vitamin C (N = 6)

iii. 17% required narcotics

Case report

 Intolerable fibrosarcoma-related pain [81]

10 g/day vitamin C for 19 days

Better control of pain by opiates

 Breast cancer with skeletal metastases—severe pain [81]

5 g/day IV vitamin C for 7 days

No further need for opiates (from day 4)

8 g/day oral vitamin C for 70 days

 Bladder cancer with skeletal metastases—intense pain inadequately controlled by morphine [81]

10 g/day IV vitamin C for 10 days

No further need for opiates

10 g/day oral vitamin C for 24 days