Guide to Coronavirus Medication Dosing

In the absence of either a vaccine or a proven cure for coronavirus, science is looking to repurpose some of our existing drugs. While these drugs are known to be safe in humans they can have side effects and can interact with other medication. HIV drug interactions can be checked here.

While coronavirus is a worry, the vast majority of people infected with it will have only mild symptoms, very much in line with a common cold. Using medication that can currently only be termed experimental to treat a harmless illness does not stack up. It does potentially stack up in the event of severe illness, so the notion of “In case of emergency break the glass” applies.

While it is possible that antiviral drugs which work against coronavirus could be used in the same way as HIV drugs are used in PrEP to prevent HIV infection this remains entirely unknown. What is known is that nobody ever got side effects from a medicine they were not taking.

Ok, so that’s the end of the disclaimers. Here’s what you need to know:

Lopinavir/Ritonavir (Kaletra) 400/100 mg every 12 hours [Details & Side Effects]

Atazanavir/Ritonavir (Reyataz) 300/100 mg once a day. [Details & Side Effects]

Darunavir (Prezista) 400-600mg every 12 hours with a medication containing 100mg of ritonavir to achieve the full effect. [Details & Side Effects]

Chloroquine dosing is complex and based on body weight. [Details & Side Effects]

60 kg or more:

1 g chloroquine phosphate (600 mg base) orally as an initial dose, followed by 500 mg chloroquine phosphate (300 mg base) orally after 6 to 8 hours, then 500 mg chloroquine phosphate (300 mg base) orally once a day on the next 2 consecutive days
Total dose: 2.5 g chloroquine phosphate (1.5 g base) in 3 days

Less than 60 kg:

First dose: 16.7 mg chloroquine phosphate/kg (10 mg base/kg) orally
Second dose (6 hours after first dose): 8.3 mg chloroquine phosphate/kg (5 mg base/kg) orally
Third dose (24 hours after first dose): 8.3 mg chloroquine phosphate/kg (5 mg base/kg) orally
Fourth dose (36 hours after first dose): 8.3 mg chloroquine phosphate/kg (5 mg base/kg) orally
Total dose: 41.7 mg chloroquine phosphate/kg (25 mg base/kg) in 3 days

For the prevention of malaria, the dose is 500mg chloroquine phosphate once a week. This dosing schedule reflects the fact that this drug stays in the system for a long time. The malaria dosing schedule is known to produce adequate blood levels so can be followed but should not continue past the 3 days as this may cause an overdose.

The dosing recommendations for hydroxychloroquine follow the same guidelines as chloroquine in that the loading dose is the acute malaria dose followed by dosing at 400 mg a week.

The loading dose for hydroxychlorquine for adults is 800 mg followed by 400 mg 6 hours later, then 400 mg on days 2 and 3 for a total dose of 2000 mg.

It takes 22 days for 1/2 the hydroxychlorquine to exit the body so a weekly top up dose of 400 mg is all that is required and extra doses, as for chloroquine may lead to toxic blood levels.

Anyone contemplating taking chloroquine or hydroxychloroquine should be tested for G6PD deficiency. Patients with this genetic trait may get massive haemolysis from it with subsequent renal failure. While this deficiency is rare in many cultures it does occur at a 10% rate Negros and a 1% rate in people who come from the Mediterranean.

It is strongly recommended that any medication a patient may have elected to source only be used as a last resort in the event of life-threatening illness.

UPDATE: 10th March – the Liverpool University, which publishes the excellent HIV medication interactions checker has just published this guide to the interactions of the experimental COVID-19 drugs.

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