Money outweighing bottle of pills on scale

Image source: Getty Images.

Imagine buying a Ferrari 488 Spider and a Porsche 911 Carrera -- every year. You'd spend more than the costs of those two sports cars if you had to pay the average wholesale price for the costliest prescription drugs.

The highest-priced drugs have two things in common: They all treat rare and dangerous diseases, and they all cost hundreds of thousands of dollars per year.

Here are the seven most expensive prescription drugs in the world -- and which companies are profiting from them.

Scientist holding bottle of Glybera

Image source: Uniqure. 

1. Glybera

Glybera is a gene therapy drug that treats adult patients diagnosed with familial lipoprotein lipase deficiency (LPLD), a rare genetic disorder that causes a large amount of fat to build up in the blood. The drug, which was developed by Dutch pharmaceutical company Uniqure, costs upwards of $1 million per year.

Uniqure won European approval for Glybera in 2012. Americans don't have access to the drug, though. The U.S. Food and Drug Administration (FDA) requested additional clinical trials before reviewing Glybera for approval. Uniqure decided against moving forward with those trials. Even though Glybera is available in Europe, the high cost of the drug has greatly limited its use.

Ravicti - gap in urea cycle

Image source: Horizon Pharma.

2. Ravicti

Ravicti is used to treat urea cycle disorders (UCD), genetic diseases that prevent the body from getting rid of ammonia. The resulting buildup of the toxic substance can lead to brain damage and death, so forgoing treatment is not an option. Horizon Pharma (NASDAQ:HZNP) sells Ravicti at an annual cost per patient of nearly $794,000. 

There are an estimated 2,000 individuals in the U.S. who suffer from urea cycle disorders that could potentially be treated by Ravicti. Horizon's drug treats seven types of UCDs, though it's unknown whether Ravicti is safe and effective for treating an especially rare type known as N-acetylglutamate synthetase (NAGS) deficiency. 

Spinraza

Image source: Biogen. 

3. Spinraza

The newest of the seven most expensive prescription drugs in the world is spinal muscular atrophy (SMA) drug Spinraza. Biogen (NASDAQ:BIIB) received FDA approval for the drug, which was initially developed by Ionis Pharmaceuticals in December 2016. Spinraza costs $750,000 for the first year of treatment.

While that price tag makes Spinraza the third-most expensive drug, the cost goes down after the first year of treatment to $375,000. That's because more injections are needed during the first year than in subsequent years.

Lumizyme

Image source: Sanofi.

4. Lumizyme

Lumizyme replaces a missing or deficient enzyme in people with Pompe disease, a genetic disorder caused by the buildup of a sugar called glycogen in the body's cells. The drug is marketed by French drugmaker Sanofi (NYSE:SNY) and costs more than $626,000 annually. 

Pompe disease is estimated to occur in one out of every 40,000 live births. However, the frequency in the African-American population is higher, at roughly one in 14,000 births. Sanofi obtained approval for an earlier Pompe disease treatment called Myozyme in 2006. However, when the company scaled up the bioreactor that produced Myozyme, the FDA required a separate approval process. This led to Lumizyme's approval and launch in 2010. 

Hand holding white pill

Image source: Getty Images.

5. Carbaglu

Like Ravicti, the second-most expensive prescription drug, Carbaglu is used to treat patients with urea cycle disorders (UCDs). Unlike Ravicti, however, Carbaglu specifically addresses N-acetylglutamate synthetase (NAGS) deficiency. The developer of the drug, Recordati Rare Diseases, has priced Carbaglu at more than $585,000 per year per patient.

Carbaglu is the only drug approved by the FDA for treating high ammonia levels caused by NAGS deficiency in patients of all ages.While every type of UCD is rare, cases caused by NAGS deficiency are the rarest of them all. Because NAGS deficiency is under-diagnosed, the actual number of individuals affected by this type of UCD remains unknown. 

Mother giving Actimmune shot to child

Image source: Horizon Pharma. 

6. Actimmune

Horizon Pharma claimed the No. 2 spot on the list with Ravicti. The company also has the sixth-costliest drug, Actimmune, which treats two rare genetic diseases: chronic granulomatous disease (CGD) and severe, malignant osteopetrosis (SMO). Actimmune is priced at more than $572,000 per year per patient.

The drug is a biologically manufactured protein known as interferon gamma, which is similar to a protein made naturally by the human body. Interferon gamma helps lower the risk and severity of infections in individuals with CGD and can slow the worsening of SMO in patients. CGD occurs in around one in 200,000 births in the U.S., whle SMO occurs in an estimated one in 250,000 births. 

Soliris

Image source: Alexion Pharmaceuticals.

7. Soliris

It wasn't too long ago that Soliris held the top spot among the most expensive drugs in the world. However, Alexion Pharmaceuticals' (NASDAQ:ALXN) drug now takes seventh place with an annual price tag of nearly $543,000.

Soliris treats two rare diseases: paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome (aHUS). PNH destroys red blood cells and affects an estimated 8,000 to 10,000 people in North America and Europe. aHUS affects the body's immune system in ways that can lead to serious complications, including blood clots. There are only 1,500 known patients diagnosed with the disease, but there could be as many as 41,000 aHUS patients in the world. 

Dollar sign made of pills

Image source: Getty Images.

And that's just the tip of the iceberg

While these were the seven most expensive drugs in the world, there are plenty of other costly medications. As of 2015, more than 90 other prescription drugs carried annual price tags of over $100,000. Five of them cost more than $400,000 per year -- just behind the drugs to make the top seven list. 

Keith Speights has no position in any stocks mentioned. The Motley Fool owns shares of and recommends Biogen and Ionis Pharmaceuticals. The Motley Fool has a disclosure policy.