Drugs are expensive. Thousands of people take drugs that cost from $50,000 to $100,000 per year, such as the cancer drugs Provenge and Avastin and the medication for multiple sclerosis, Lemtrade. But a much smaller number of people have rare conditions that require lifesaving drugs whose prices are astronomical—up to $400,000 per year, prices that may reflect the cost of developing the medication.

A rare or orphan disease is a condition affecting 200,000 or fewer individuals in the United States. Rare diseases once were the neglected stepchild of drug makers, who wanted medicines they could sell to millions of patients. Today, conditions afflicting far smaller numbers are seeing booming interest from the industry. And more companies are taking advantage of grants, tax credits and other incentives of the Orphan Drug Act passed in 1983. In the preceding decade, only 10 drugs for rare diseases had been approved, but more than 400 were approved from 1984 through 2012.

Thinking you pay way too much for your monthly prescriptions? These amazingly expensive drugs may put things into perspective.

Soliris

Soliris has been made famous by Forbes as the world’s single most expensive drug, coming in at $409,500 a year. Soliris is used to treat paroxysmal nocturnal hemoglobinuria, a rare Marchiafava-Micheli blood disease that affects 8,000 Americans.  The med generated $541 million in sales for Alexion Pharmaceuticals in 2010.

Paroxysmal nocturnal hemoglobinuria causes the breakdown of red blood cells and release of hemoglobin into the urine. The sudden, recurring attacks—which are often triggered by stress, exertion or infection—result in anemia. Little is known about the incidence of paroxysmal nocturnal hemoglobinuria, which can affect people of any age, but it’s believed to occur at a rate of about one to five per one million. The drug Soliris, made by Alexion Pharmaceuticals and approved by the Food and Drug Administration in 2007, stops the breakdown of cells. Soliris is a monoclonal antibody—a product engineered in the lab to mimic a natural substance. Studies show it leads to a dramatic improvement of symptoms and reduces the risks of complications.

Elaprase

Patients who suffer from Hunter syndrome, an inherited disease caused by a lack of the enzyme iduronate sulfatase can find relief in the recombinant form of this enzyme, but at an incredibly high price of $375,000 each year. Some estimates put its annual cost as high as $657,000. Each vial of the drug is reported to cost $4,215 each, and in the U.S. alone, the 500 Americans who suffer from Hunter syndrome spent a combined $353 million on Elaprase in 2009.

The incurable condition occurs in about one in 150,000 people, almost always males. The disorder typically appears in childhood and impairs growth and mental development. Afflicted children also have a distinct thickening of facial features. A late-onset version of Hunter syndrome is usually milder but can delay growth and damage joints, vision and hearing. Elaprase is an injected medication that replaces the missing enzyme. Manufactured by Shire, it was approved in 2006 improves patients’ ability to walk.

Naglazyme

Naglazyme is right behind Elaprase’s reported $375,000 price tag, coming in at the bargain price of just $365,000. This medication is for a rare connective tissue disorder called Maroteaux-Lamy syndrome, which is caused by a deficient enzyme that breaks down large sugar molecules called glycosaminoglycans. The condition occurs in about one of every 200,000 to 600,000 people. The deficiency causes growth retardation in early childhood in addition to heart disease. Naglazyme is made by Biomarin and was approved in 2005. The administration of the drug improves growth and joint movement, as well as range of motion and pain management.

Cinryze

Patients with hereditary angioedema (HAE) suffer from severe swelling, often in the face and airways, caused by low levels or improper function of the C1 inhibitor protein. This condition is hereditary, and there’s usually a family history, but often, deaths from hereditary angioedema go undiagnosed and reported as a sudden and premature death of a family member. This makes the condition relatively rare, and the treatment is quite expensive: an estimated $350,000 per year for Cinryze, an injectable man-made protein form of complement C1 esterase inhibitor. Cinryze maker Viropharma has mapped out yearly sales of the drug ranging from $95 million to as much as $350 million.

Folotyn

This medication is used to treat an aggressive type of cancer of the lymph system, peripheral T-cell lymphoma, which has spread throughout the body. The lymph system is comprised of white blood cells and T cells which fight viruses. There are many types of lymphoma, but T-cell lymphoma is rare, affecting about one to two people per 100,000.

Folotyn, made by Allos Therapeutics, was approved in 2009 and helps prolong survival. Typically, patients will take the drug for about six weeks, but even in that short amount of time, the bill for this treatment is staggering — around $30,000 per month. It’s given to people who have exhausted all other options for treatment and whose cancer has recurred. The drug, an injection, is thought to kill cancer cells; however studies so far have not shown that it prolongs survival. Still, Folotyn was approved as part of the FDA’s accelerated drug approval process to address the needs of people who have a poor prognosis.

Myozyme

Developed by Genzyme, Myozyme costs up to $100,000 per year for child treatment, and about $300,000 per year for adults. Myozyme was created to treat a rare and often fatal disease, Pompe, which disables the heart and skeletal muscles. Often affecting infants, most of its sufferers die in the first year, and those who do survive typically need assistance like ventilators and wheelchairs. But thanks to Myozyme, some patients can do fairly well with the disease, able to speak, walk, and feed themselves. The drama behind creating such an expensive, yet lifesaving drug, was depicted in the movie Extraordinary Measures, sharing the race against time and profit motives experienced in the drug’s development.

Acth

If you think $30,000 per month is insane, consider this: it’s a bargain compared to the approximate $115,000 per month families pay for ACTH. This drug is used to treat infantile spasms, seizures that often affect infants 4 to 6 months of age. Daily injections of ACTH are given for a period of weeks up to several months. At $23,000 per vial, patients often use 6 to 7 vials per course, and often go through two courses, which adds up to more than $300,000 in prescription drug bills. Unfortunately, ACTH is not FDA-approved to treat infantile spasms, and that means families may have trouble getting their insurance companies to pay for this mind-boggling bill.

Arcalyst

Rare genetic conditions like Familial Cold Auto-inflammatory Syndrome and Muckle-Wells Syndrome are inflammatory disorders that cause the body to develop symptoms without a known cause, including virus and illnesses, and can affect the bones, joints, and major organs, leading to deafness, kidney impairment, and vision loss. These inherited conditions impair the immune systems of sufferers, but with Arcalyst, the symptoms associated with these syndromes can be treated and even prevented. It’s even been found to help prevent gout flares, but all of this helpful treatment comes at a very high cost: a reported $250,000 per year of treatment.

Ceredase/Cerezyme

Patients with Gaucher disease, a condition that causes lumps of fat to build up in various places in the body, including the heart, brain, and spleen, suffer from the disease due to a missing enzyme. With Ceredase, made from human placentas, that enzyme can be replaced. But placentas don’t come cheap: the price of this drug is $150,000 per year. A new version, Cerezyme, came out in 1994, made with genetically engineered hamster cells, and was expected to be cheaper, but unfortunately for Gaucher disease sufferers, the price has actually gone up to $200,000 per year for the average patient. The drug has annual sales of more than a billion dollars.

Fabrazyme

Like so many other terribly expensive drugs on this list, Fabrazyme replaces a necessary enzyme in the human body. Patients with Fabry disease suffer from the lack of or faulty enzyme that is needed to metabolize lipids. Without it, lipids are not effectively broken down, and can build to harmful levels in the nervous system, cardiovascular system, eyes, and kidneys, leading to cloudiness of the cornea, increased heart attack and stroke risk, as well as an enlarged heart and impaired kidneys. It’s not hard to understand why this condition is just downright harmful, and why it’s so important to treat. Using Fabrazyme, patients can make up for their enzyme deficiency, reducing deposits throughout the body. The treatment is reported to cost $200,000 for a year of treatment, that is, if you can get it: in 2009, Fabrazyme maker Genzyme’s plant was shut down due to contamination, and is just now resolving its manufacturing problems.

Aldurazyme

Aldurazyme is used to treat a genetic enzyme condition, a far too common and expensive issue on this list. The condition in this case is Hurler syndrome, a metabolic disorder in which the lack of an enzyme keeps the body from breaking down certain sugars and proteins properly. Like Fabry disease, sugars and proteins not broken down will build up, leading to enlarged organs, breathing issues, decreased physical abilities, and more. With Aldurazyme, breathing and walking ability can be improved, but it does cost a pretty penny: $200,000 per year. The drug is usually given on a weekly basis in a clinic or hospital setting, which may incur additional costs as well.