Mazzarella et al. Topical finasteride study concentration

[Nevis]

Question to all chemists out there:
Am I playing with the right units here on the Mazzarella et al 1997 topical finasteride study?

They used a 0.005% finasteride solution in 50%PG, 25% alcohol, 25% distilled water. That is, 5 parts finasteride per 1000 solution?

That would be equivalent then to one 0.5mg (1/2 a Propecia pill) dissolved in 100mL of a 50/25/25 solution (which is approximately the vehicle for most OTC minoxidil preparations right?).

I could be making a Chem101 mistake with units? :dunno:

Just clarifying here, not trying the solution. Seems amazingly small though for even "encouraging" results as the authors state. Assuming one goes through 100mL of such a solution in 1.67 months, using 1mL 2x/day (as per minoxidil application and the schedule used in the study), then one is only using 1mg Propecia every 3.3 months (~100 days)!. That's a 100 fold change in your propecia usage/intake.

IF my chemistry here is ok...I did a search on a few sites and I found more than 3 different quotes on how to make the Mazzarella solution (none with complete explanation that I could backtrack and compare where/why they were using the numbers they did), thus my question!!!!

 

[m0rpheus]

good question. I would like to know also!

 

[Jm0311]

no chemists here.

 

[Nevis]

I've seen 2 posts which claim 5mg propecia into 100mL normal minoxidil mixture (50/25/25) gives you a 0.005% solution like the Mazzarella study. But 5mg/100mL = 0.05% if you follow my admittedly uneducated logic. Where am I missing the extra decimal place?

 

[Bryan]

But 5mg/100mL = 0.05% if you follow my admittedly uneducated logic. Where am I missing the extra decimal place?

Huh?? Convert all quantities to grams. 5 mg = 0.005 grams. 100 mL = 100 grams. Therefore, 0.005 / 100 = 0.00005 = 0.005%

 

[Old Baldy]

Bryan's correct Nevis.

Just remember that a milligram is one thousandth of a gram (i.e., .001 of one gram). So you are dealing with "three zeros" in the decimal equation when milligrams are being used.

Memorize that "three zeros rule" and percentages will become second nature when making concoctions with milligrams in them.

 

[Nevis]

...and there's my obvious mistake! I knew I was missing something obvious when no other posters were questioning the math.

it wasn't that I was missing metric magnitude conversions, it was the move to grams. I was totally overlooking the compatibility of units themselves, not the rules of moving decimals. That was silly.

Sorry and thanks

 

[Old Baldy]

Oh, I forgot to mention that, on a rough comparison, you can equate one milliliter to one gram. (The weight of water works that way [i.e., one gram weight of water equals one milliliter volume of water]).

So, I generally equate grams and milliliters as one to one when making concoctions. For what I use, it isn't too far off when I've tested the comparisons on my scale.

That's a rough comparison that I have just memorized for convience's sake. It ain't perfect by any means but good enough IMHO.

Btw, I knew a guy at work who wanted to make his own concoctions. He scored the highest in the State of Michigan when he took his CPA exam decades ago. He missed the comparisons like you did also. It ain't a matter of stupidity.

 

[Jack]

That would be equivalent then to one 0.5mg (1/2 a Propecia pill) dissolved in 100mL of a 50/25/25 solution (which is approximately the vehicle for most OTC minoxidil preparations right?).

Are you dissolving the finasteride into the minoxidil ? So is it safe to say that the minoxidil and finasteride won't react in a bad way? I know there are some minoxidil formulations sold which contain finasterid , but not sure how they added the finasteride .

 

[Nevis]

Thanks OldBaldy...but still as silly mistake. I used these message boards as a crutch and just asked the question like a bad student instead of sitting down for a few more minutes with pen and paper and thinking clearly. It's a mistake I hate when others make, so I hate it doubly so when I do it myself.

And yeah, the 1mL water = 1 gram is an approximation, but for what we're doing here it's fine. If we were going for absolute perfect, I suppose we'd have to adjust it all for the weight of the 50% PPG, which is slightly more dense than water, and the alcohol, which is less dense?...but I think we're good enough.

@Jack: You're correct that the study I'm referring to used a 50/25/25 mixture that has no minoxidil in it. Am I positive that the minoxidil addition won't affect the finasteride? No. But will the finasteride dissolve? yes. You could also purchase the component pieces of the solution and make the study's preparation that way too...to be certain. I was only worried about checking my calculation/logic, not actually making the mixture.

@ Bryan: if you care to comment on this article specifically, as I know you've talked it/discussed the issue of topical finasteride and the range of results the few studies we have report---what's your take on the Mazzerella et al?

General question too: What about the safety of non-internal dosings to others? How long would the finasteride stays "active" if it transfers to another surface (pillow case, surfaces via hand transfer etc) and would that sort of concentration be anything to worry about in those sort of unintended transfers where you're dealing in trace volumes of the mixture?

 

[pproctor]

FWIW. The convention is that liquid formulations are generally made up weight/volume ( e.g., mg/ml ) not weight/weight. (e.g. mg/gm ). These are pretty much equivalent when the solvent is water, but wander off a bit when it is somethng else such as alcohol or propylene glycol.

One reason is that it is easier to dispense a volume of a liquid than it is to weigh it out. Further, the volume can adjusted in case adding the active ingredient changes it a bit. Sticking to the convention also cuts down errors.

This also holds for doses expressed in percent. E.g., 5% minoxidil means 5 grams minoxidil per 100 cc's total volume of the formulation, no matter what the vehicle is.

BTW: 20 "standard drops" equals 1 ml. Pretty much everything that dispenses drops uses this convention.

Peter H. Proctor, PhD,MD

 

[RealBrotzu]

Mazzarella solution is effective according to a guy who has been using it in the last six months.