Vinpocetine is mainly marketed as a dietary supplement for cognitive enhancement, Alzheimer’s, dementia, and ischemic stroke; however, several products are marketed toward students as brain supplements for increased cognitive performance. Additionally, vinpocetine is used by bodybuilders to enhance visual acuity, memory, and focus and to rapidly reduce body fat. Human exposure to vinpocetine typically occurs through oral consumption. Marketed as a dietary supplement in the United States, vinpocetine is regulated by the Food and Drug Administration (FDA) under the Dietary Supplement Health and Education Act of 1994. Analysis of vinpocetine supplements have shown that in a significant number of products, the actual vinpocetine content varied from what was stated on the label, which could result in higher doses than what is recommended by the product labels. Because of the limited literature indicating that vinpocetine may not be safe for use during pregnancy and the possibility for widespread exposure to women of childbearing age, the National Toxicology Program (NTP) conducted prenatal developmental toxicology studies. In these studies, time-mated Sprague Dawley (Hsd:Sprague Dawley SD) rats and New Zealand White (Hra:NZW SPF) rabbits received vinpocetine (99.3% pure) in 0.5% methylcellulose by gavage from implantation on gestation day (GD) 6 (rats) or 7 (rabbits) to the day before expected parturition (GD 20 for rats; GD 28 for rabbits). Evidence of vinpocetine-related maternal and fetal toxicity was examined in the dose range-finding study in rats followed by the standard prenatal developmental toxicity study in rats. A dose range-finding study in rabbits was conducted to see if effects occurred in a second species and which species might be more sensitive, but a standard prenatal developmental toxicity study was not performed in rabbits.
Dose range-finding prenatal developmental toxicity study in rats
Groups of 10 time-mated female rats were administered 0, 20, 40, 80, 160, or 320 mg vinpocetine/kg body weight per day (mg/kg/day) (based on the most recent body weight) in 0.5% aqueous methylcellulose by gavage from GD 6 to GD 20. Vehicle control (0 mg/kg) animals received aqueous methylcellulose.
All animals survived to the end of the study. Clinical observations were limited to red or brown vaginal discharge, discoloration of the nares, and piloerection. Dose-related decreases were observed in mean maternal body weight and mean body weight gains from GD 6 to GD 21 in groups administered 40 mg/kg or greater. When adjusted for gravid uterine weight, maternal body weights of the 160 and 320 mg/kg groups were significantly lower than those of the vehicle control group. Concomitant treatment-related, dose-dependent decreases in maternal feed consumption in groups receiving 40 mg/kg or greater was also noted. There was a significant, treatment-related effect on percent postimplantation loss in all dose groups. At doses of 80 mg/kg or greater, dams exhibited total resorption of their litters except for one dam in the 160 mg/kg group with live fetuses. No external malformation or variations attributed to vinpocetine administration in fetuses were observed.
Prenatal developmental toxicity study in rats
Due to the postimplantation loss observed at doses of 80 mg/kg and greater in the dose range-finding study, 60 mg/kg was chosen as the high dose for the prenatal developmental toxicity study. Groups of 25 time-mated female rats were administered 0, 5, 20, or 60 mg/kg/day (based on the most recent body weight) in 0.5% aqueous methylcellulose by gavage from GD 6 to GD 20. Vehicle control (0 mg/kg) animals received aqueous methylcellulose.
All animals survived to the end of the study. Treatment-related clinical findings were red or brown vaginal discharge in the 20 and 60 mg/kg groups. Significantly decreased mean maternal body weights and mean body weight gains were found in the 60 mg/kg group that were associated with a significant increase in postimplantation loss, including total litter resorption in 12 dams. A treatment-related decrease in feed consumption was found also in the 60 mg/kg group. Because of the increased postimplantation loss in the 60 mg/kg group, a significant decrease was found in the number of live fetuses per litter and in gravid uterine weight.
A small number of litters and fetuses were viable for evaluation at 60 mg/kg. In the viscera, treatment-related increased incidences of ventricular septum defect were in all exposed groups. In the skeleton, treatment-related findings included significantly increased incidences of incomplete ossification of the thoracic centrum in the 20 and 60 mg/kg groups and full supernumerary thoracolumbar ribs in the 60 mg/kg group.
Dose range-finding study in rabbits
Groups of eight time-mated female rabbits were administered 0, 25, 75, 150, or 300 mg/kg/day (based on the most recent body weight) in 0.5% aqueous methylcellulose by gavage from GD 7 to GD 28. Vehicle control (0 mg/kg) animals received aqueous methylcellulose.
All rabbits survived until the end of the study except one 150 mg/kg female that was removed on GD 25 due to abortion. There were no clinical observations related to vinpocetine treatment. Significant decreases in mean maternal body weight gains were observed in the 150 and 300 mg/kg groups and a treatment-related decrease in feed consumption in these groups.
An exposure-related effect was observed on embryo-fetal survival in the 300 mg/kg group with an increase in early resorptions per litter resulting in an increase in percent postimplantation loss and a significant decrease in the number of live fetuses per litter. These findings in the 300 mg/kg group were also associated with a significant decrease in mean gravid uterine weight. No exposure-related effects were observed on embryo-fetal survival in any group administered 150 mg/kg or less. There were no external malformations or variations attributed to vinpocetine exposure.
Data from this rabbit dose range-finding study supported findings observed in the rat dose range-finding study and rat prenatal developmental toxicity studies (increase in postimplantation loss) with exposure to vinpocetine.
Conclusions
Under the conditions of the rat prenatal study, there was clear evidence of developmental toxicity of vinpocetine in Hsd:Sprague Dawley SD rats attributable to increased postimplantation loss and increased incidences of ventricular septum defects, thoracolumbar ribs (full), and incomplete ossification of the thoracic centrum in the absence of overt maternal toxicity.
National Toxicology Program (NTP). 2020. NTP developmental and reproductive toxicity technical report on the prenatal development studies of vinpocetine (CASRN 42971-09-5) in Sprague Dawley (Hsd:Sprague Dawley SD) rats and New Zealand White (Hra:Nzw Spf) rabbits (gavage studies). Research Triangle Park, NC: National Toxicology Program. DART Report 03. https://doi.org/10.22427/NTP-DART-03