Zinc
"The Tolerable Upper Intake Level (UL) for adults is 40 mg/day"
https://www.ncbi.nlm.nih.gov/books/NBK222317/
"Increasing the intracellular Zn(2+) concentration with zinc-ionophores like pyrithione (PT) can efficiently impair the replication of a variety of RNA viruses, including poliovirus and influenza virus."
https://pubmed.ncbi.nlm.nih.gov/21079686/
Zinc 2+ ion inhibits SARS-CoV-2 main protease and viral replication in vitro
https://pubmed.ncbi.nlm.nih.gov/34514483/
Quercetin
"quercetin has the ability to inhibit the main protease of SARS-CoV-2, known as Mpro or 3CLpro (3C-like protease)"
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8066963/
"Although specific evidence to support dosing recommendations is limited, most clinical studies use quercetin 500 to 1,000 mg per day in divided doses."
https://www.drugs.com/npp/quercetin.html
Copper
"The maximum dose for adults 19 years and older is 10,000 mcg or 10 milligrams (mg) per day."
https://www.kobmel.com/care/how-much-copper-per-day/amp/
"Heavy metals including gold and silver are antibacterial, but copper’s specific atomic makeup gives it extra killing power, Keevil says. Copper has a free electron in its outer orbital shell of electrons that easily takes part in oxidation-reduction reactions (which also makes the metal a good conductor). As a result, Schmidt says, it becomes a “molecular oxygen grenade.” Silver and gold don’t have the free electron, so they are less reactive"
https://www.smithsonianmag.com/science-nature/copper-virus-kill-180974655/
Silver
"The EPA Reference Dose ("RfD"), the recommended safe daily intake limit of silver from all sources, is:
0.005 milligrams ("mg"), which is 5 micrograms ("mcg"), per kilogram (which is about 2.2 pounds) of body weight."
http://www.silverfacts.com/safety.html
"Silver nanoparticles have mainly been studied for their antimicrobial potential against bacteria, but have also proven to be active against several types of viruses including human imunodeficiency virus, hepatitis B virus, herpes simplex virus, respiratory syncytial virus, and monkey pox virus."
https://pubmed.ncbi.nlm.nih.gov/22024958/
Silver nanoparticles inhibit hepatitis B virus replication
https://pubmed.ncbi.nlm.nih.gov/18505176/
Glycyrrhizin
"Licorice root has been used in daily doses from 760 mg to 15 g for ulcer and gastritis. Higher doses given for extended periods of time may pose a risk of hypokalemia. The acceptable daily intake (ADI) for glycyrrhizin is suggested to be 0.2 mg/kg/day."
https://www.drugs.com/npp/licorice.html
Glycyrrhizin Effectively Inhibits SARS-CoV-2 Replication by Inhibiting the Viral Main Protease
https://pubmed.ncbi.nlm.nih.gov/33918301/
Curcumin
"The Allowable Daily Intake (ADI) value of curcumin has been determined by the European Food Safety Authority to be 0-3 mg per kilogram of body weight, or roughly 0-1.4 mg per pound."
https://www.webmd.com/diet/health-benefits-curcumin
"Curcumin, the primary curcuminoid compound found in turmeric spice, has shown broad activity as an antimicrobial agent, limiting the replication of many different bacteria and viruses."
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7599685/
Curcumin and Natural Derivatives Inhibit Ebola Viral Proteins: An In silico Approach
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5757320/
Artemisinin
"The immediate efficacies of two oral dosage regimens of artemisinin were investigated in 77 male and female adult Vietnamese falciparum malaria patients randomly assigned to treatment with either 500 mg of artemisinin daily for 5 days (group A; n = 40) or artemisinin at a dose of 100 mg per day for 2 days, with the dose increased to 250 mg per day for 2 consecutive days and with a final dose of 500 mg on the fifth day (group B; n = 37)."
https://pubmed.ncbi.nlm.nih.gov/11897585/
Beyond malaria: The inhibition of viruses by artemisinin-type compounds
https://pubmed.ncbi.nlm.nih.gov/29305894/
"The bioavailability of a substance can fluctuate, depending on the route of administration. Intravenous administration, or a direct line into the bloodstream, is typically considered 100% bioavailability, as all of the substance will reach target cells. In oral administration routes, AKA when you take a pill, the amount of medicine or supplement you receive depends on many factors, including your diet and your personal metabolism.
Bioavailability has become a new and upcoming science in recent decades."
https://biologydictionary.net/bioavailability/
"Drug Half-life (t1/2) is defined as the amount of time required for the drug concentration to be reduced to exactly half its initial concentration or amount in the blood. The half-life is the time required for half of the drug to be metabolized and eliminated from the body. The half-life of the drug is useful in determining the dosing frequency"
https://www.medicinenet.com/what_does_half_life_mean_in_drugs/article.htm