Frequently Asked Questions
What is Pharmacogenomics?
The terms pharmacogenomics and pharmacogenetics are often used interchangeably to describe a field of research focused on how genes affect individual responses to medicines. Whether a medicine works well for you—or whether it causes serious side effects—depends, to a certain extent, on your genes.
Just as genes contribute to whether you will be tall or short, black-haired or blond, your genes also determine how you will respond to medicines. Genes are like recipes—they carry instructions for making protein molecules. As medicines travel through your body, they interact with thousands of proteins. Small differences in the composition or quantities of these molecules can affect how medicines do their jobs.
These differences can be due to diet, level of activity, or the medicines a person takes, but they can also be due to differences in genes. By understanding the genetic basis of drug responses, scientists hope to enable doctors to prescribe the drugs and doses best suited for each individual.
Aren’t prescribed medicines already safe and effective?
While standard doses of most medicines work well for most people, some medicines don’t work at all in certain people or cause annoying and sometimes dangerous side effects. For example, codeine is useless as a painkiller in nearly 10 percent of people, and an anticancer drug, 6-mercaptopurine, is extremely toxic in a small fraction of the population.
Your genes determine a lot about how you look. They also play a key role in how your body responds to medicines.
How do scientists gather pharmacogenomic information?
Many pharmacogenomic findings are based on knowledge of biochemical pathways within cells. For example, scientists already knew a lot about the enzymes that break down the anticancer drug irinotecan when its toxic effects in certain patients came to light. This knowledge allowed researchers to rapidly pinpoint a genetic variant of one of these enzymes as the cause of the dangerous reaction. Scientists have developed a genetic test for this variant so that doctors can adjust the dosage for those at risk for serious side effects.
Advances can also come from studies that accompany clinical drug trials. After obtaining permission from participants, some pharmaceutical companies collect DNA samples from people in clinical trials. Scientists then analyze the samples together with results of the clinical trial to identify genetic variations that correlate with a drug’s effectiveness or toxicity.
Pharmacogenomic researchers have already identified many genes whose variations affect drug responses. They also know where to look for the numerous others they are bound to discover in the future. The availability of the human genome sequence, which was completed in 2003, led to the HapMap project, an international effort to catalog common genetic differences among human beings. These resources are providing a treasure trove of genetic information that is expected to speed advances in pharmacogenetics.
How will pharmacogenomics affect the quality of health care?
In the future, pharmacogenomics will increasingly enable doctors to prescribe the right dose of the right medicine the first time for everyone. This would mean that patients will receive medicines that are safer and more effective, leading to better health care overall.
Also, if scientists could identify the genetic basis for certain toxic side effects, drugs could be prescribed only to those who are not genetically at risk for these effects. This could maintain the availability of potentially lifesaving medications that might otherwise be taken off the market.
Another challenge facing pharmacogenetics is the number and complexity of interactions a drug has with biological molecules in the body. Variations in many different molecules may influence how someone responds to a medicine. Teasing out the genetic patterns associated with particular drug responses could involve some intricate and time-consuming scientific detective work.
While routine pharmacogenetic testing could ultimately save our health care system billions of dollars by improving drug effectiveness and safety, the savings could be offset by the additional cost of genetic tests.
In what ways can doctors use pharmacogenomics to help treat their patients?
Pharmacogenetics can be used by doctors to identify the optimal dose and/or medicine for each patient.
The right dose
Dosage is usually based on factors such as age, weight, and liver and kidney function. But for someone who breaks down a drug quickly, a typical dose may be ineffective. In contrast, someone who breaks down a drug more slowly may need a lower dose to avoid accumulating toxic levels of the drug in the bloodstream. A pharmacogenetic test can help reveal the right dose for individual patients.
The right drug—for depression
Depression can be treated with a variety of different medicines, and it is often time-consuming and difficult to find the drug(s) that works best for each person. In the future, genetic testing may take some of the guesswork out of choosing a drug regimen. These tests are likely to involve analyzing a person’s liver enzymes, especially those in the cytochrome P450 family, which are largely responsible for processing antidepressants.
Other tests that may prove useful to psychiatrists will detect differences in the molecules targeted by antidepressants, such as the serotonin transporters targeted by a large class of antidepressants called selective serotonin reuptake inhibitors (SSRIs). Scientists have uncovered evidence for a link between a person’s response to SSRIs and variations in serotonin transporters.
The right drug—for cardiovascular disease
Statins, the most widely prescribed drugs worldwide, help prevent cardiovascular disease by reducing the level of “bad” cholesterol in the bloodstream. While statins work well for many patients, responses are highly variable and doctors must adjust the dosage for each person.
Researchers have discovered that variants in a number of molecules—including those that break down or transport statins, as well as the statins’ molecular target in the cholesterol production pathway—contribute to the variable response among individuals. Using results of genetic tests, doctors may one day be able to prescribe the right dose from the start and more quickly reduce their patients’ risk of dangerous cardiovascular events such as heart attack and stroke.
How will pharmacogenetics affect the design, development and availability of new medicines?
Pharmacogenomic knowledge will enable pharmaceutical companies to design, develop and market drugs for people with specific genetic profiles. Testing a drug only in those likely to benefit from it could streamline its development and maximize its therapeutic benefit.
The FDA, which monitors the safety of all drugs in the United States, considers pharmacogenomics to be a valuable tool in the development of new medical products. To date, the FDA has approved a number of genotyping kits relevant to pharmacogenomics, including one that screens for variants in the cytochrome P450 enzymes, which process many kinds of drugs. In most cases the FDA encourages, but does not require, companies to submit pharmacogenomic data with new drug applications. This data is only required for medicines that were developed based on pharmacogenomics.
How do I get a pharmacogenetic test?
Ask your doctor, who can order a test. If you take a test, a technician will rub a cotton swab along the inside of your cheek to collect cells. These tests typically cost a few hundred dollars and may be covered by your health insurance company.
How do I fulfill PQRS requirements?
To fulfill PQRS requirements physicians must submit:
- Data on at least 9 measures across three quality domains to qualify for the 2014 incentive
- For at least 50% of their eligible patients
- Starting in 2016 penalties in the form of payment deductions will be applied to EPs who do not satisfactorily report data (based on 2014 reporting)
What does it mean for the doctor?
- Individual EPs who meet the satisfactory submission criteria will qualify to earn a payment equal to .05% of their total estimated Medicare Part B PFS allowed charges for covered professional services furnished during that same reporting period.
- Payment adjustments of -2.0% for EPs who do not meet satisfactory submission criteria will begin in 2016.
What are the incentives?
- The applicable PQRS incentive amounts are:
- 2014: 0.5 percent
- No PQRS incentive payments are scheduled past 2014.
- The applicable PQRS payment adjustment amounts are:
- 2016: -2.0 percent (based on 2014 submission)
- 2017: -2.0 percent (based on 2015 submission)
What is a doctor’s liability for pain medication addiction?
People who are recovering from surgery or very painful injuries are often prescribed narcotic or opioid pain medications. These medications are very effective in reducing pain, but can have the unfortunate side effect of addiction.
If a doctor overprescribes addictive pain killers, can the patient sue for addiction? A doctor may be liable in a malpractice lawsuit, if negligence can be proven.
What steps should I take to cover my bases when prescribing pain meds?
- Patients who are clearly addicted to opiates should be referred a physician specializing in addiction medicine for rehabilitation. Do not accept this patient back until the patient does this.
- Excellent documentation is a must. Make sure your records meet all requirements of state laws and regulations.
- If you are not a certified specialist in pain medicine, refer pain management patients out to one who is.
- Be sure of the patient’s identity. Require valid, government issued identification, preferably two, and ask the patient a few background questions that can be verified. Identity theft is common among drug abusers seeking prescription medications.