The Effects of Aspirin on the Metabolic Availability of Ascorbic Acid in Human Beings

Effect of allopurinol, sulphasalazine, and vitamin C on aspirin induced gastroduodenal injury in human volunteers.

“…When given paren-We used vitamin C in this study for two Sound to have a protective reasons: firstly because it is a free oxygen radimodels of gastric injury, cal scavenger, and secondly because it has been id phenylbutazone,26 but suggested that the gastric mucosa is more prone to injury (particularly by aspirin) in the Aspirin + allopurinol presence of diminished leucocyte ascorbic acid concentrations.38 40 aspirin diminished uptake of ascorbate into Lanza score Figure 5: Frequency distribution graphs for Lanza grade in treatment regimen. *p<0005 by comparison with aspirin X -522 6r leucocytes,42 45 46 which might permit the unopposed synthesis and release of free oxygen radicals by neutrophils activated after NSAID induced gastric mucosal injury. 4 Changes in absorption may explain the otherwise paradoxical protection of the duodenum by vitamin C. The pKa of ascorbic acid is 41.39 Hence at normal gastric pH, vitamin C is present predominantly as ascorbic acid, which will tend to be oxidised to dehydroascorbic acid as the pH rises in the duodenum.…”

“…Vitamin C supplements, however, had no effect on aspirin induced gastric release of reactive oxygen metabolites and did not protect against gastric injury in our study.Ascorbate is a hydrophilic compound that can-Aspirin + vitamin C* not scavenge lipophilic radicals within lipid membranes,43 a property that might prevent it reacting in the lumen with radicals induced by aspirin. It may still have a role as an antioxidant following absorption, however, as it is known to be concentrated in the gastric epithe-lium44 and reaches high concentrations after oral supplementation.42[45][46][47][48] Possibly the most important mode of absorption is by an active, sodium dependent transport mechanism from the small bowel.49 50 There is, however, some evidence that suggests that aspirin impairs sodium dependent transport mechanisms.5' tion of vitamin C with aspirin seemed to impair absorption,42 although this has been I the duodenum after each disputed 45 46. In all three studies, however, and placebo.…”

Vitamin C aspirin interactions in laboratory animals

“…On the leucocytes, some interference with the mechanisms for active uptake of ascorbic acid is possible. It may be that the enzymes necessary for the transport of ascorbic acid across the leucocyte cell membrane are affected (9).…”

Ascorbic acid levels in stored blood and in patients undergoing surgery after blood transfusion

“…In some cases there may be a pre-existing deficiency of ascorbic acid before surgery is undertaken, such as in peptic ulceration (Cohen and Duncan, 1967;Dymock et al, 1967) and in patients with gastro-intestinal haemorrhage (Russell et al, 1968). In particular, aspirin is a known ascorbic acid tissue desaturator (Loh et al, 1974), and it has been suggested that subclinical scurvy may be responsible for haemorrhage after aspirin ingestion (Coffey and Wilson, 1975).…”