10 Happy Accidents from the Annals of Drug Discovery

The pharmaceutical industry spends untold millions of dollars trying to discover the next wonder drug. The potential profits from a breakthrough drug can be counted in the billions of dollars — and a great new medication can improve the lives of countless people.

But sometimes the greatest breakthroughs in drug development come from the weirdest sources. Here are 10 drugs that started their lives as poisons, road coverings, or as treatments for very different maladies.

Top image by nocturnalMoTH on deviantArt.

10 Happy Accidents from the Annals of Drug Discovery


10. Rogaine
Rogaine (Minoxidil) first came to market as Loniten, a drug used to treat high blood pressure. Users observed an interesting side effect — Loniten increased the darkness of hair and caused hair growth. The Upjohn Corporation soon produced a decreased strength version to be sold over the counter for direct application to the scalp.

One of the downsides of Rogaine is the need for continued application to prevent hair loss, but it's not banned by the International Olympic Committee like another anti-baldness drug. (See below.)

10 Happy Accidents from the Annals of Drug Discovery


9. Pink Bismuth
Bismuth is an element, so it did not follow the typical drug development scheme. The heavy metal is of little apparent use, but is known for its extremely low thermal conductivity and low human toxicity. Bismuth's pharmaceutical application comes through the consumption of Bismuth subsalicylate, the active ingredient in the anti-diarrheals Pink Bismuth (better known as Pepto-Bismol) and Kaopectate. The element is also used in the form of Bismuth subgallate, a component of the internal deodorant Devrom, an over the counter medication for preemptive removal of fecal odor. If you ever have a blow torch and some Pepto-Bismol around, you can recover the solid bismuth oxide slag if you are ever bored enough and like fire.

10 Happy Accidents from the Annals of Drug DiscoveryS


8. Botulinum toxin
Botulinum is the most powerful neurotoxin known to humanity, but for some reason, people started injecting the protein into their foreheads to stop eyelid twitching and cosmetically to paralyze muscles in the forehead to alleviate frown lines in 1989.

The cosmetic use of Botox opened up the availability of the protein and made an avenue for other uses, with medical grade botulinum toxin currently used to alleviate symptoms of Parkinson's disease, bladder spasms, and chronic migraines.

10 Happy Accidents from the Annals of Drug Discovery


7. Finasteride
Finasteride, better known as Proscar or Propecia, is a molecule initially used for treatment of an enlarged prostate. Like Loniten, an interesting side effect occurred with finasteride users, as long-term use resulting in a decrease in male pattern baldness.

Finasteride competes with testosterone for binding to 5-alpha reductase, decreasing the volume of the prostate and preventing testosterone from conversion to more powerful androgens in the scalp. Propecia also masks performance enhancing drugs, leading to the banning of the drug in many sports.

10 Happy Accidents from the Annals of Drug Discovery


6. Coal tar
A brownish black liquid left over from the use of coal as fuel, coal tar contains a plethora of hydrocarbons and is traditionally used to pave roads or prevent lice infestation and dandruff when added to shampoos.

The National Psoriasis Foundation recently proposed the topical application of coal tar to skin afflicted with psoriasis, as coal tar slows the growth of skin cells in the applied area.

10 Happy Accidents from the Annals of Drug DiscoveryS


5. Penicillin
The single most important discovery on this list, and one I'm sure most of you are familiar with. Alexander Fleming is noted for discovering that Penicillium chrysogenum, a blue-green fungi that loves damp environments, secretes a substance with antibacterial properties when grown in the right situation. A stray spore of mold landed landed on a bacteria culture used in Fleming's research, leading to his keen observation.

In the years since Fleming's happenstance discovery, historians paid close attention to Greek records of using mold to cure ailments along with the 19th Century bacterial research of James Tyndall and Louis Pasteur.

10 Happy Accidents from the Annals of Drug Discovery


4. Acetylsalicylic acid
Hippocrates wrote that an extract from the bark of the willow tree relieved pain and quelled fevers, with several cultures, including Native Americans, independently determining the special attributes of the bark. The active ingredient in the willow tree bark, salicylic acid, is a plant hormone playing roles in photosynthesis and plant growth.

We don't gnaw on bark any more to relieve a headache or fever (although that would be interesting), we just grab a bottle of aspirin, containing the derivative acetylsalicylic acid, instead, as it is a little easier the digestive tract than salicylic acid.

10 Happy Accidents from the Annals of Drug DiscoveryS


3. Warfarin
Your dad or grandmother probably takes Warfarin (also known as Coumadin) to prevent blood clots, going in to check their INR readings every couple of weeks. The same thing your relatives take as a preventive measure to extend their lives started out as a quick and dirty way to kill rats.

A relatively low dose of warfarin will cause rats to bleed out (working in the same manner as it would to prevent blood clots in humans), due to a much higher drug to mass ratio. Warfarin is still used as a rat poison, but it is becoming less common as some rats are developing a resistance to the molecule.

10 Happy Accidents from the Annals of Drug DiscoveryS


2. Viagra
Sildenafil citrate, also know as the scourge of retirement homes or Viagra in some circles, began as compound UK-92,480, reaching phase 1 clinical trials for treatment of hypertension and angina. Sildenafil citrate didn't perform well in trials to treat either malady, but molecule did give patients erections.

Pfizer purchased the company that developed UK-92,480 and quickly switched the aim of sildenafil citrate, making it the first drug on the market specifically to induce erections in 1998. Viagra is also used (off-label) for alleviation of jet lag. Sildenafil citrate is available in high doses under the name Revatio, a pharmaceutical treatment for pulmonary hypertension. Don't get too happy if you're given a prescription for Revatio, as your body quickly acclimates to the dosing schedule (20 mg, multiple times a day), tossing aside the glamorous side effect.

10 Happy Accidents from the Annals of Drug Discovery


1. Nitrogen Mustards
Release of mustard gas on citizens of Italy during World War II decreased the number of lymphocytes in exposed individuals. Clinical trials underway at the same time in secret at Yale University used nitrogen mustard to combat cancer. Bis(2-chloroethyl)methylamine (better known as the chemical warfare agent HN2) is one of the best known nitrogen mustards, with HN2 becoming the first anticancer chemotherapy drug.

HN2 is rarely used in modern chemotherapy and is still classified as a schedule 1 weapon by the Chemical Weapons Convention.The molecule spawned several derivatives over the years — analogues at the front line of modern cancer treatment.

Images courtesy of CC sources, the University of Florida, and Pfizer. Sources linked within the article.