Table 3.

Current clinical trials evaluating the effect of antioxidant compounds on neurological manifestations in COVID-19.

Antioxidant(s)	Protocol	Neurological or Psychiatric Conditions Assessed
Vitamin C	▪Bolus doses of 50 mg/kg in 50-mL of either dextrose 5% in water or normal saline for 30 to 60 min, every 6 h for 96 h (200 mg/kg/day and 16 doses in total) (N = 800, protocol in recruiting)	○Pain, discomfort, anxiety/depression, mobility (by 6 months) and consciousness (up to 28 days)
Zinc and vitamin C	▪Standard treatment + 220 mg (zinc) and 1 g (vitamin C)/24 h/10 days (N = 50, protocol not yet recruiting)	○Muscle or body aches, headache, loss of taste, loss of smell by 28 days
	▪Standard treatment + 8000 mg (vitamin C) divided into 2–3 doses/day with food and 50 mg (zinc gluconate) daily at bedtime (N = 520, protocol in recruiting)	○Headache, loss of taste, loss of smell by 28 days
	▪80 mg (zinc)/500 mg (vitamin C) daily for 42 days additional to hydroxychloroquine, ivermectin, and povidone iodine treatment (N = 4257, protocol completed)	○Change in smell by 42 days
	▪Standard treatment + 8000 mg (zinc) divided into 2–3 doses/day with food and 50 mg (zinc gluconate) daily at bedtime (N = 214, protocol with recruitment completed)	○Muscle and body aches, headache, new loss of taste and new loss of smell by 28 days
Hydroxychloroquine, vitamin C, vitamin D, and zinc	▪Treatment with hydroxychloroquine will last 1 day. Treatment with vitamin C, vitamin D, and zinc will last 12 weeks (N = 600, protocol in recruiting)	○Headache and difficulty speaking by 24 weeks
Melatonin	▪Oral 10 mg/three times a day for 14 days (N = 30, protocol in recruiting)	○Headache, loss of taste, loss of smell and dizziness by 28 days
Glycine and N-acetylcysteine	▪Supplementation by 2 weeks (N = 64, protocol in recruiting)	○Change in cognition and memory assessed up to 10 weeks
Glycine	▪Habitual treatment + 0.5 g/kg/day by nasogastric tube/4 equal doses per day (N = 82, protocol in recruiting)	○Consciousness assessed up to 12 months
Vitamin C, vitamin E, melatonin, and N-acetylcysteine	▪One antioxidant plus pentoxifylline. Vitamin C 1 g/12 h. Vitamin E 800 mg/24 h. Melatonin 50 mg/24 h. N-acetylcysteine 600 mg/12 h (N = 11, protocol active not recruiting)	○Consciousness for 7 days post antioxidant dose
Previfenon®	▪Contains 250 mg of epigallocatechin-3-gallate (EGCG). Total EGCG dose per patient will be 750 mg/day (3 capsules/8 h) for 40 consecutive days (variable time between 60 and 70 days) (N = 524, protocol in recruiting)	○Myalgia, loss of smell, loss of taste, headache by 40–70 days of intervention
Hesperidin and diosmin	▪1000 mg/8 h for 7 days and 1000 mg/12 h times daily for 3 days (N = 100, protocol not yet recruiting)	○Myalgia by 14 days
Fuzheng Huayu Tablet (FZHY) and vitamin C	▪FZHY tablet administration: 0.4 g/tablet, 1.6 g/time, three times/day, medicine to be taken after meals. Vitamin C tablets administration: 0.2 g/time, three times/day. (N = 160, protocol in recruiting)	○Insomnia by 24 weeks
Resveratrol	▪Capsules of 1.0 g, orally once a day for six months. (N = 30, protocol not yet in recruiting)	○Depression by 9 months

www.clinicaltrials.gov, accessed on 22 April 2021 [294].