Fwd: [SSRI-Research] Drug Reaction Testing - CYP2D6, CYP2C9, and CYP2C19 screens

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JustSayNo

Tue, 09 Dec 2003 21:19:46 -0500

[sSRI-Research] Drug Reaction Testing - CYP2D6, CYP2C9, and CYP2C19

screens

 

Drug Reaction Testing

http://www.healthanddna.com/drugreactiontest.html

 

Do not alter the dosage amount or schedule of any drug you are taking

without first consulting your doctor or pharmacists.

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Research shows that of all the clinical factors such as age, sex, weight,

general health and liver function that alter a patient's response to drugs,

genetic factors are the most important. This information becomes even more

crucial when you consider the fact that adverse reactions to prescription

drugs are killing about 106,000 Americans each year -- roughly three times

as many as are killed by automobiles. This makes prescription drugs the

fourth leading killer in the U.S., after heart disease, cancer, and stroke.

 

We currently offer CYP2D6, CYP2C9, and CYP2C19 screens that can help your

physician or druggist predict your particular response to more than a

quarter of all prescription drugs. These include such important medications

as Coumadin (Warfarin), Prozac, Zoloft, Paxil, Effexor, Hydrocodone,

Amitriptyline, Claritin, Cyclobenzaprine, Haldol, Metoprolol, Rythmol,

Tagamet, Tamoxifen, Valium, Carisoprodol, Diazepam, Dilantin, Premarin, and

Prevacid (and the over-the-counter drugs, Allegra, Dytuss and Tusstat).

 

Approximately half of all Americans have genetic defects that affect how

they process these drugs. There are four different types of metabolizers,

and we all fall into one of these categories for the variable pathways in

Cytochrome P450 (this Cytochrome is responsible for creating the enzymes

that process chemicals of all kinds through our bodies.) The easiest way to

understand this is to picture a two lane highway.

 

· If you are the first type which is the norm, you would be an EXTENSIVE

metabolizer. Both lanes of the highway are open and moving. Medications

prescribed in normal doses will be metabolized by your body.

 

· If you are the second type, you would be an INTERMEDIATE metabolizer. This

means that one lane of that highway is open and moving and the other lane is

not, causing you to metabolize the medications more slowly. In this case you

will need a lower dosage, and there is a chance of medications building up

in your system causing adverse effects. It is especially important to

monitor medications if you are in this category.

 

Intermediate metabolizers through the 2C9 pathway, for instance, have an

increased risk of bleeding incidences when taking the common blood thinner

Coumadin or Warfarin. For this reason, a recent article in the Journal of

the American Medical Association recommends screening for CYP2C9 variants to

reduce the risk of adverse drug reactions in these patients.

 

· The third type is a POOR metabolizer. In this case both lanes of the

highway would be stopped. There is a possibility that alternate routes can

be found, but this type of metabolizer is potentially very dangerous, as

there is a great chance for the medication to build up in your system making

you very sick, or even killing you.

 

For example, a poor metabolizer of Phenytoin, a common antiepileptic would

not be able to process the drug and would actually have an increased rather

than decreased risk of seizure if prescribed this drug.

 

· The fourth type of metabolizer is ULTRA EXTENSIVE. This means you have

additional lanes for processing, picture an Indy 500 speedway. In this

instance, you literally burn through medications. If you were an Ultra

extensive metabolizer through the 2D6 pathway and while in surgery and your

doctor gave you codeine as a pain killer, you would receive no pain relief

because the codeine would be metabolized so fast that it would have little

or no effect on you.

 

The Testing Process

 

The process is simple. We send you a blood collection kit in the mail. You

can either make an appointment with your doctor or we will provide you with

the contact information for a phlebotomist in your area. Blood samples are

overnighted to our laboratory and results are typically available in 15

business days.

 

Currently Available Tests

 

CYP2D6 (cytochrome P450 2D6) is the best studied of the DMEs and acts on

one-fourth of all prescription drugs, including the selective serotonin

reuptake inhibitors (SSRI), tricylic antidepressants (TCA), betablockers

such as Inderal and the Type 1A antiarrhythmics. Approximately 10% of the

population has a slow acting form of this enzyme and 7% a super-fast acting

form. Thirty-five percent are carriers of a non-functional 2D6 allele,

especially elevating the risk of ADRs when these individuals are taking

multiple drugs. Drugs that CYP2D6 metabolizes include Prozac, Zoloft, Paxil,

Effexor, Hydrocodone, Amitriptyline, Claritin, Cyclobenzaprine, Haldol,

Metoprolol, Rythmol, Tagamet, Tamoxifen, and the over-the-counter

diphenylhydramine drugs, Allegra, Dytuss, and Tusstat. CYP2D6 is responsible

for activating the pro-drug codeine into its active form and the drug is

therefore inactive in CYP2D6 slow metabolizers.

 

CYP2C9 (cytochrome P450 2C9) is the primary route of metabolism for Coumadin

(Warfarin). Approximately 10% of the population are carriers of at least one

allele for the slow-metabolizing form of CYP2C9 and may be treatable with

50% of the dose at which normal metabolizers are treated. Other drugs

metabolized by CYP2C9 include Amaryl, Isoniazid, Sulfa, Ibuprofen,

Amitriptyline, Dilantin, Hyzaar, THC (tetrahydrocannabinol), Naproxen, and

Viagra.

 

CYP2C19 (cytochrome P450 2C19) is associated with the metabolism of

Carisoprodol, Diazepam, Dilantin, Premarin, and Prevacid.

 

Other tests we are planning to provide include:

 

NAT2 (N-acetyltransferase 2) is a second-step DME that acts on Isoniazid,

Procainamide, and Azulfidine. The frequency of the NAT2 " slow acetylator " in

various worldwide populations ranges from 10% to more than 90%.

 

The advantages of Genelex's consumer genetic testing include:

 

· Safety. Decrease the chance that you will be the victim of an adverse drug

reaction. More than 100,000 hospitalized Americans die of adverse drug

reactions and two million outpatients have serious episodes each year.

Knowledge of your DNA Drug Reaction Profile may help your physician or

druggist prevent this from happening.

 

· Efficacy. Prescription drugs on the market today are usually prescribed by

trial and error because they have been tested and approved in a " one size

fits all " fashion. If you eliminate a particular drug more rapidly than the

norm, taking the normal dose may be a complete waste of time. The drug

simply will not work as prescribed, and it may take a while to discover

this.

 

· Responsibility. Play a more active role in your health, your family's

health, and in healthcare at large. DNA testing for drug reactions is just

coming onto the market and you, the consumer, can help all of us take this

major step toward better medicine.

 

Call Genelex today at 800-523-3080 to order testing, order on-line, or

download the order form and fax or mail in your order. Don't forget to take

a look at our other informational genetic testing products now as you

receive significant discounts when ordering tests at the same time.

 

 

Founded in 1987, Genelex Corporation is accredited by the American

Association of Blood Banks (AABB)Parentage Testing Committee in DNA

parentage testing since 1992 and is Washington State Medical Test Site No.

MTS-3919 CLIA No. 50D0980559. Genelex was accredited by the American Society

of Crime Laboratory Directors Laboratory Accreditation Board (ASCLD LAB) in

forensic DNA testing from 1998-2003 and has contributed to the validation of

National Institute of Standards and Technology (NIST) Standard Reference

Materials.

 

3000 First Ave., Suite One, Seattle, WA 98121

800 523-3080

©1995-2001, Genelex Corporation. .