Pharmacogenetics

                Recently I attended a fascinating lecture on pharmacogenetics. WAIT! Please read the rest of this paragraph before you dismiss this subject as boring! Have you ever been prescribed a medication that you took for a month or more, before your doctor finally admitted it wasn’t working for you? Do you wonder why a pain pill works great for your wife, but doesn’t touch YOUR pain? Have you known someone who had a severe adverse reaction to a medication? Well, pharmacogenetics solves all those questions/problems.

                If we are looking at only the last question, the one about adverse drug reactions (ADRs), research tells us that ADRs cause almost 200,000 deaths annually, and account for over 10% of hospital admissions. So ADRs alone should make us take notice of pharmacogenetics! The official definition of pharmacogenetics is “the study of inherited geneticodifferences in drug metabolic pathways which can affect individual responses to drugs, both in terms of therapeutic effect as well as adverse effects.”  (That reminds me of a Liberty Mutual commercial: “Page 5 says blah blah, blahblahblah, blah.”) In plain language, it means that our genes influence our response to medicinal drugs, as well as our potential adverse reaction to them.

                Pharmacogenetics is being used extensively at St. Jude Hospital, a hospital that specializes in treating children with cancer. Testing leukemia patients for the gene that produces the enzyme responsible for metabolizing the drugs used to treat leukemia has produced amazing treatment changes, and saved many a child’s life in the process.  There is optimism that St. Jude will soon have a clinical program that allows genetic information to be routinely used across all their patients, not just the ones with leukemia.

                Gene tests are normally performed only when a drug needs to be prescribed, but at St. Jude, every child with leukemia is tested preemptively, because the results impact not just which drug is used, but the dosage as well. Out in the rest of the world, the challenge is to educate clinicians in the available testing, results, and how to use them. Currently, there have been around 20 genes identified that can provide useful predictions of reactions to about 100 drugs (about 7% of all drugs approved by the FDA).   For proponents of testing, it is frustrating that the tests are usually not done until after a patient has had a problem with a medication, at which point it may be too late to serve any useful purpose.

Among the medications that we know, for a fact, would be influenced by testing are HIV and Hepatitis C medications, antidepressants, anticoagulants, and a few specific drugs like Plavix, Isoniazid, cocaine, procainamide, and Vitamin E. Looking at antidepressant drugs alone, many times the patient for whom they are prescribed must take a medication for 2 to 4 weeks to determine its effects. If there is no effect, another drug must be tried for another 2-4 weeks. Theoretically, a depressed person could spend a year taking one drug after another before the “right” one is found, and furthermore, find the right dose.  In fact though, the testing can be done across all categories of drugs, whether it be for high blood pressure, gastrointestinal, urological, psychotropic or anti-anxiety drugs.  Results can show which drugs the individual’s system is capable of breaking down normally, versus the drugs the body cannot break down normally. The test needs to be done only ONCE in a lifetime, because the genes don’t change.  Imagine how useful that information would be in a situation such as being a patient in the emergency room!

                Unfortunately, like most things in healthcare today, it comes down to MONEY.  Although testing would lower the costs that come about due to ADRs and trial-and-error-medicine, and would also lower the number of deaths that occur due to ADRs and ineffective prescriptions, the test still costs $1000-$2500, beyond the bank account of most of us, and certainly beyond what most insurance carriers will pay.

                HIPAA (Health Insurance Portability and Accountability Act) is also a factor. HIPAA controls everyone’s accessibility to healthcare information, which means there has to be secure storage of your information, so it would not be readily available when needed.

                Sometimes we become so up to our necks in alligators, it’s impossible to drain the swamp.