I very rarely discuss animal experiments on this blog. Their applicability to clinical situations in human patients is almost invariably doubtful. Of course, this does not mean that they cannot be important; on the contrary, they may point the way towards relevant research and help formulate hypotheses.
This study might be exceptionally relevant in this way. To investigate the safety and efficacy of megadose sodium ascorbate in sepsis, sheep were instrumented with pulmonary and renal artery flow-probes, and laser-Doppler and oxygen-sensing probes in the kidney. Conscious sheep received an infusion of live Escherichia coli for 31 hours. At 23.5 hours of sepsis, sheep received fluid resuscitation (30 mL/kg, Hartmann solution) and were randomized to IV sodium ascorbate (0.5 g/kg over 0.5 hr + 0.5 g/kg/hr for 6.5 hr; n = 5) or vehicle (n = 5). Norepinephrine was titrated to restore mean arterial pressure to baseline values (~80 mm Hg).
Sepsis-induced fever (41.4 ± 0.2°C; mean ± SE), tachycardia (141 ± 2 beats/min), and a marked deterioration in clinical condition in all cases. Mean arterial pressure (86 ± 1 to 67 ± 2 mm Hg), arterial PO2 (102.1 ± 3.3 to 80.5 ± 3.4 mm Hg), and renal medullary tissue PO2 (41 ± 5 to 24 ± 2 mm Hg) decreased, and plasma creatinine doubled (71 ± 2 to 144 ± 15 µmol/L) (all p < 0.01).
Direct observation indicated that in all animals, sodium ascorbate dramatically improved the clinical state, from malaise and lethargy to a responsive, alert state within 3 hours. Body temperature (39.3 ± 0.3°C), heart rate (99.7 ± 3 beats/min), and plasma creatinine (32.6 ± 5.8 µmol/L) all decreased. Arterial (96.5 ± 2.5 mm Hg) and renal medullary PO2 (48 ± 5 mm Hg) increased. The norepinephrine dose was decreased, to zero in four of five sheep, whereas mean arterial pressure increased (to 83 ± 2 mm Hg).
These physiologic findings were subsequently confirmed in a coronavirus patient with shock by compassionate use of 60 g of sodium ascorbate over 7 hours.
The authors concluded that IV megadose sodium ascorbate reversed the pathophysiological and behavioral responses to Gram-negative sepsis without adverse side effects. Clinical studies are required to determine if such a dose has similar benefits in septic patients.
As always with animal experiments, it is difficult to extrapolate to clinical situations in human patients. However, the fact that the authors did try their approach on one COVID-19 patient is encouraging. I agree with their conclusion that careful human studies are now required.