User:Colin/PriceMistakes

I examined the drugs citing MSH Price Guide (see User:Colin/MSHData), looking just at those beginning with the letter A (31 drugs). The prices we offer cannot be verified by the source and require extra data and original research, and misuse WHO's Defined Daily Dose. But ignoring all that, are they actually correct? I found six examples of clear mistakes. So one in five drug prices are simply wrong. I add Diazepam at the end, since it is an example in the RFC.

Aciclovir

"The wholesale cost as of 2014 to 2016 was between US$0.03 and US$0.12 for a typical dose by mouth."

This is a bit confusing as it doesn't say "developing world", gives a range of dates, and doesn't say what it is treating. It is clear those prices correspond exactly to the $0.0300 and $0.1183 unit price for a 400mg tablet in 2014 alone. The DDD is 4000mg (herpes zoster). According to Drugs.com, the adult treatment is 800mg five times a day for 7 to 10 days (BNF agrees). So we have quoted the price for one tablet, yet patients take two in each dose. The cited source does not supply a "typical dose" so the statement is unsourced as well as wrong.

Activated charcoal (medication)

"The wholesale costs in the developing world is between US$0.46 and US$0.86 per dose."

The cited ACT/DDD of activated charcoal is 5g for "treatment of common diarrhea", and the price given corresponds with taking 40 (!) of these tiny black 125mg tablets to reach a 5g daily dose. I can't find a reliable source recommending activated charcoal for common diarrhea but some websites suggest this is a folk remedy in some countries and that one would consume tablets in multiple doses throughout the day up to 5g in a day. There's no way someone is swallowing 40 tablets in one go, so the text should say "per day" rather than "per dose". The article also needs to explain that this daily dose is for common diarrhea, because the lead is all about treatment of poisoning. The emergency room treatment of poisons uses significantly higher doses (e.g. 25 - 100g, minimum 25g) and more likely a liquid suspension of 25g or 50g rather than fiddly little 125mg tablets. The price per dose here is not only wrong but the unspecified treatment indication very misleading.

Albendazole

"The wholesale cost in the developing world is between 0.01 and US$0.06 per dose."

The price given corresponds to one 200mg tablet. The drug treats lots of different parasitic worm infestations and the dose and frequency/duration varies on indication. The DDD is 400mg for "the treatment of different nematode infections e.g. ascariasis (roundworm) and hookworm infections" and indeed the treatment dose for ascariasis and hookworm infections is a single 400mg dose, and nearly all other infections in adults require 400mg doses. So the article has given the price per 200mg tablet, not per 400mg dose.

Allopurinol

"The wholesale cost in the developing world is about US$0.81–3.42 per month"

The price here corresponds to a 300mg tablet taken once daily and cites a record with no suppliers (4 buyers). The DDD is 400mg (for gout) which doesn't divide by 300mg. This is a good case where the DDD and the tablet size cited does not permit simple maths. Drugs.com say the dose is initially 100mg and goes to 200-300 for mild gout and 400 to 600 in divided doses for moderately severe gout, with a maximum of 800mg per day. The tablet strength we should have cited is the 100mg tablet which has 5 suppliers (and 4 buyers). The 100mg tablet has far more likely usage and hence actually has suppliers, so we've cited the wrong record. If that record had been used, the price per month would be "US$1.39 to $12.50", which is considerably different to the article text.

Artemether/lumefantrine

"The wholesale cost in the developing world is between US$0.10 and US$1.2 per day as of 2014"

The price here is "per day" and the source record has no DDD. So any statement (OR or otherwise) of a daily cost is unsourced. It is hard to come up with the numbers from the source. The $1.2 would appear to be 4 times $0.2997 dearest tablet price, but 4 times $0.0120 cheapest tablet price is only $0.048, not $0.10. Drugs.com recommend "4 tablets as single initial dose, followed by 4 tablets after 8 hours, and then 4 tablets twice a day (morning and evening) for the following 2 days (total course: 24 tablets)". And BNF recommend "Initially 4 tablets, followed by 4 tablets for 5 doses each given at 8, 24, 36, 48 and 60 hours (total 24 tablets over 60 hours)". So 4 tablets is one dose and total treatment is 24 tablets over three days. A cost "per day" might then be 8 tablets, which would make the $0.10 minimum value correct, but not the maximum. We've got the dose and daily dose confused and regardless, this is a short treatment course of 3 days so a daily dose is inappropriate.

Aspirin

"As of 2014, the wholesale cost in the developing world is US$0.002 to US$0.025 per dose."

The price here corresponds to a single 300mg tablet citing a record with ATC Code for "Analgesics". Most reliable sources say that for pain relief, the dose is "1 to 2 tablets every 4 to 6 hours as needed", though the BNF permits 1 to 3 tablets up to a max of 4g per day. The DDD is 3g which corresponds to 10 tablets and minimum 4-hourly intervals would only permit 6 doses per day. There really is no one "dose" for aspirin for pain relief but if we accept the DDD is a guide (it isn't) then one tablet per dose is insufficient and two tablets would be a typical dose. For this common medicine (as with ibuprofen and paracetamol) saying "dose" is ambiguous for our readers. As an aside, all the suppliers offer the tablet at 0.5 cents or less. The 2.5 cent upper price comes from a single buyer record -- this is an outlier price. The source (and WHO) recommend using the median of supplier prices, to avoid outliers.

Diazepam

"The wholesale cost in the developing world is about US$0.01 per dose as of 2014."

There is no One Dose for diazepam: it has so many many uses. The DDD/ATC Code at the IMPGG is N05BA01 and that is for treating anxiety. Our article does not state "anxiety" as the indication for that dose, and it does matter. Drugs.com tell us the "Usual Adult Dose for Anxiety: ORAL: 2 to 10 mg orally 2 to 4 times a day", and BNF says "2 mg 3 times a day, then increased if necessary to 15–30 mg daily in divided doses". You can see from the latter and the algorithm at Defined daily dose article, how WHO came up with 10mg a day, which is taken in divided doses (in the UK there are 2mg, 5mg and 10mg tablets available). So taking a 10mg tablet 3 times a day is very much at the extreme end of the scale, which is why IMPPG does not list any suppliers for that tablet strength. The drug in that tablet size is not generally available in the developing world. They do list the 5mg tablet with 8 suppliers and 5 buyers. In that case the article text would be "$0.006 to $0.036 per dose". Btw, updating the record to 2015 would result in text "$0.003 to $0.030": the lower unit price is 2 x cheaper after just one year.