A new paper is circulating, leading to a new & improbable claim that "ivermectin treats staph aureus."

There is absolutely no evidence that this is true.

A short thread about pharmacology (MICs, IC50s, and Cmax) explaining why this claim is so unlikely.
1/ ImageImage
This paper by Ashraf et al is an in vitro study of repurposed meds on MRSA & MSSA.

Right off the bat, there are weird things going on. They grew 21 strains and report results for...2

And when they treated those strains with ivermectin, they used some insanely high doses...
2/
How high?
They found the minimum inhibitor conc (MIC) to kill MSSA was 12.5 ug/mL
How high is that? Let's do some math:
Ivermectin has two forms B1a & B1b. The average MW is 868 g/mol.Converting 12.5 ug/mL mass concentration to molar concentration we get 14 uM! Yikes!
3/ ImageImage
Is an MIC of 14 uM a lot?

Well, when people take ivermectin as prescribed (0.2mg/mL daily) the plasma level is *much much* lower: The Cmax for ivermectin is ~50 nM (or 0.05 uM).

The in vivo dose (Cmax) is way less than the dose required in vitro (MIC): 280x lower in fact!
4/ Image
Incidentally this is the same reason that many of us were skeptical that ivermectin could inhibit SARS-CoV-2 in vitro.
In that case the dose required in vitro was 5 uM. Which was "only" 100x less than required.

Here's a 🧵 I did about that from May.

5/
Bottom line:
- a new dubious in vitro study finds that ivermectin kill MRSA/MSSA at a dose of 14 uM (MIC), which is 280x higher than can actually be achieved in people
- So IVM kills MRSA but at a dose that would kill people too
- PSA: don't take IVM to treat MRSA or COVID

6/6

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More from @nickmmark

24 Oct
I’m old enough to remember when the #cultOfVitaminC claimed it was unethical to do more RCTs of vitamin C in sepsis. Now the #CultOfIvermectin is making the same claims about ivermectin in COVID.

Charlatans & quacks don’t like RCTs. Especially when they disprove snake oil.
1/ Image
I guess this shouldn’t come as a surprise; It’s the exact same people (Marik et)

After vitamin C as a miracle cure imploded in January 2020 they decided to go double or nothing on a different miracle cure: ivermectin.

2/ Image
It should come as no surprise that they are making literally identical arguments about ivermectin that they made about their last miracle cure:
“I’ve seen it work thousands of times”
“Real world medicine”
“unethical to do RCTs”
Any negative study must be “designed to fail”
3/
Read 4 tweets
7 Oct
To the ivermectin die hards asking "What about Uttar Pradesh?!?" Perhaps you can answer the question "Why *ONLY* Uttar Pradesh?"
You realize that IVM was tried and failed in Peru, Brazil, & elsewhere. Why have the benefits of IVM *never* been seen in RCTs or other countries?
1/
Alternatively, perhaps the "Uttar Pradesh Miracle" has to do with proven interventions: lockdown, curfew, mask mandate, testing/quarantine, & vaccines.

There's also major under-reporting in UP. (Unless you think IVM has decreased deaths from car accidents & cancer too).
2/ From https://www.nature.com/articles/s41562-020-01009-0 Source: https://www.medrxiv.org/content/10.1101/2021.08.04.2
To those saying UP "was only 5% vaccinated" when cases started to drop, realize that vaccinating frontline people can/does reduce transmission & vaccinating high risk people reduces mortality.

If you are looking for why cases REMAIN low, UP is >50% partially vaxxed right now
3/
Read 6 tweets
7 Oct
Here’s an interesting ventilator waveform; can anyone explain what’s going on during this inspiratory hold maneuver?
Another clue:
Y’all nailed it! This is a large bronchopleural fistula (BPF) causing air leak.

See how airway pressure drops with inspiration hold?

The ventilator measures exhaled (or “returned”) volumes and is alarming “Low MV” b/c most of the air is going out the chest tubes not the ETT
1/
Read 4 tweets
6 Oct
Yesterday I shared a fun fact that black coffee cools faster than coffee with milk/cream.

Today I woke up early and decided to do an experiment. What followed was interesting & more than a little messy (🤷 that’s science!)

A short 🧵 on ☕️ science
1/
First some background:

Supposedly black coffee ☕️ cools faster for two reasons:
1. Black coffee radiates more heat because black objects have greater emissivity (due to Stefan Boltzmann)
2. Milk 🥛 increases viscosity & decrease evaporative cooling

Should be easy to test?
2/
Methods:
I made coffee & (tried to) warm the 🥛 to the same temperature as the ☕️.

I aliquoted the coffee and combined w/ or w/o 50 ml milk, bringing to the same volume (250ml).

Then I tried to pour both simultaneously into identical cups but managed to make a big mess. 🙊
3/ ImageImageImageImage
Read 7 tweets
5 Oct
When #VaccineMandates for healthcare workers (HCWs) were announced many "experts" warned that there would be a huge exodus of staff in protest.

So far this hasn't happened.

Instead we've just made staff and patients a lot safer.

A short 🧵 of examples
1/
MUSC lost 5 employees out of 17,000 (0.02%)

Indiana University lost 125 workers out of 35,800 (0.3%). Most were part time.

Inova Health lost 89 of 20,000 workers (0.4%).

CristianaCare lost 150 workers out of over 13,400 (that's 1.1%). Most were part time. Just 12 were RNs
2/
Novant Health suspended 375 employees out of 35,000 for non-compliance. 200 got vaccinated. 175 left (0.5%)

New York Presbyterian lost about 250 out of 48,000 employees (0.5%).

UCHealth lost 119 of over 26000 employees (0.4%)
3/
Read 8 tweets
5 Oct
Fun fact: if you make two cups of coffee, one with milk and one black, which will cool faster?
Counterintuitively, the black coffee cools off FASTER.

(Yes adding cold milk 🥛 to hot coffee ☕️ does cool it off somewhat but the question is about the RATE of cooling. Also the ☕️ will reach room temperature first.)

But WHY is this?
Buckle up for some cool morning physics!
There are two reasons:
1. Dark objects radiate heat faster (this has to do with the Stefan Boltzmann law & black body radiation)
2. Viscosity slows down evaporation (milk/cream thickens the coffee; evaporation is an important mechanism of cooling)

We’ll talk more about each…
Read 9 tweets

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