4 ms·

Therapeutic index of chloroquine isn't very high, and at the doses it's recommended for corona it's rather close to lethal doses, something like within an order

Therapeutic index of chloroquine isn't very high, and at the doses it's recommended for corona it's rather close to lethal doses, something like within an order of magnitude. Malaria prophylaxis is dosed -once- a weeek. Half-life 60-70 hours. Covid treatment is -twice daily-.

sudosysgen 7y ago
Actually, no. The therapeutic index of chloroquine in the treatment of covid-19 is relatively high. Some people take chloroquine or hydroxychloroquine at about half the acute dosage used for covid-19 (autoimmune disorders) for literal years. Given the half life as you mentioned, once or twice a week with enough lead time would be a sufficient dosage against covid-19 too. It's just that if you want to reach the concentration of chloroquine that you would have to take it over a long time otherwise, you need very high doses. And since you're already infected and have a ton of the virus, you also need higher concentrations than for prophylaxis.
- tim333 7y ago
  The Chinese use 1g/day for treatment. A single dose of 3g can be fatal so not a massive margin. That said they've used it on hundreds of patients without adverse effects from the drug and probably a lot of lives saved from its effects on the virus.
- internet_user 7y ago
  chloroquine is not frequently used for autoimmune. At doses used for corona, it is within 50% of margin, or even lower if you are a slow metabolizer of an LD50 dose. plaquenil on the other hand does have a higher therapeutic index. The other major disadvantage is that these drugs can interact with protease inhibitors.
  - hackeerTwo 7y ago
    > The other major disadvantage is that these drugs can interact with protease inhibitors What are the possible consequences of this?
    - internet_user 7y ago
      Death. Kaletra, a protease inhibitor, is a combination of two drugs, one of which is a CYP3A4 inhibitor. It is used with some success on coronavirus patients. Co-administering this with chloroquine 500mg/BID could easily result in chloroquine concentrations well above LD50.

sudosysgen 7y ago

Actually, no. The therapeutic index of chloroquine in the treatment of covid-19 is relatively high. Some people take chloroquine or hydroxychloroquine at about half the acute dosage used for covid-19 (autoimmune disorders) for literal years. Given the half life as you mentioned, once or twice a week with enough lead time would be a sufficient dosage against covid-19 too. It's just that if you want to reach the concentration of chloroquine that you would have to take it over a long time otherwise, you need very high doses. And since you're already infected and have a ton of the virus, you also need higher concentrations than for prophylaxis.

tim333 7y ago
The Chinese use 1g/day for treatment. A single dose of 3g can be fatal so not a massive margin. That said they've used it on hundreds of patients without adverse effects from the drug and probably a lot of lives saved from its effects on the virus.
internet_user 7y ago
chloroquine is not frequently used for autoimmune. At doses used for corona, it is within 50% of margin, or even lower if you are a slow metabolizer of an LD50 dose. plaquenil on the other hand does have a higher therapeutic index. The other major disadvantage is that these drugs can interact with protease inhibitors.
- hackeerTwo 7y ago
  > The other major disadvantage is that these drugs can interact with protease inhibitors What are the possible consequences of this?
  - internet_user 7y ago
    Death. Kaletra, a protease inhibitor, is a combination of two drugs, one of which is a CYP3A4 inhibitor. It is used with some success on coronavirus patients. Co-administering this with chloroquine 500mg/BID could easily result in chloroquine concentrations well above LD50.