Method of Dosing a Patient with Multiple Drugs Using Adjusted Phenotypes of CYP450 Enzymes

Abstract

A method of treating a patient with multiple drugs using adjusted phenotypes of CYP450 enzymes to assess the risk of adverse drug reactions occurring due to drug-enzyme interactions. CYP450 enzyme genotypes and phenotypes are measured in a patient. The phenotypes are scored numerically. The drugs intended for treatment are scored numerically for their ability to induce or inhibit the CYP450 enzymes. The drug scores are used to adjust the CYP450 phenotype scores relative to inducing or inhibiting the enzymes. An accurate adjusted phenotype score for a given CYP450 enzyme is converted to an accurate adjusted phenotype. Any of the intended drugs for treatment that are substrates for the given CYP450 enzyme can be evaluated for risk of an adverse drug reaction based on the adjusted phenotype. This method of rapid risk assessment provides an accurate basis for decisions regarding changes in dose, eliminating a drug, or replacing a drug.

Claims

1. A method of treating a patient with multiple drugs, comprising: 1) Obtaining tissue or fluid from a patient and analyzing the tissue or fluid for CYP450 enzyme genotypes; 2) converting the CYP450 enzyme genotypes to standard baseline phenotypes used to designate a given patient's ability to metabolize drugs for each CYP450 enzyme; 3) providing a numerical score for each standard baseline phenotype based on degree of drug metabolism; 4) identifying whether each of said multiple drugs is an inducer or inhibitor of each of the CYP450 enzymes; 5) for each drug that is an inducer, adjusting the standard baseline phenotype scores for the CYP450 enzymes which are induced, to indicate increased drug metabolism and for each drug that is an inhibitor, adjusting the baseline standard phenotype scores for the CYP450 enzymes which are inhibited, to indicate decreased drug metabolism, thereby obtaining a total adjusted phenotype score for each of the CYP450 enzymes which are induced or inhibited; 6) converting the adjusted phenotype scores to adjusted phenotypes for said CYP450 enzymes which are induced or inhibited; 7) identifying, for each CYP450 enzyme that has an adjusted phenotype, each of said multiple drugs that are substrates for said each CYP450 enzyme that has an adjusted phenotype; 8) determining risk of occurrence of adverse events with the use of each of said multiple drugs identified in step 7, the determining of said risk being based upon the adjusted phenotype of each CYP450 enzyme for which each of said multiple drugs is a substrate; and 9) adjusting the dose of each of said multiple drugs identified in step 7, the adjusting being based on the determination of said risk, and treating the patient with each of said multiple drugs having the adjusted dose.

2. The method of claim 1 wherein the standard baseline phenotypes range from poor to intermediate to normal to rapid to ultrarapid and wherein the standard baseline phenotype scores increase in amount negatively from normal to ultra rapid and wherein the standard baseline phenotype scores increase in amount positively from normal to poor.

3. The method of claim 1 further identifying whether each of said multiple drugs is a strong, medium, or weak inducer or a strong, moderate, or weak inhibitor of each of the CYP450 enzymes.

4. The method of claim 2, further comprising for each drug that is an inducer adding a negative number, increasing in amount from a weak inducer to a strong inducer, to the standard baseline phenotype scores for the CYP450 enzymes which are induced by said each drug, and for each drug that is an inhibitor adding a positive number, increasing in amount from a weak inhibitor to a strong inhibitor, to the standard baseline phenotype scores for the CYP450 enzymes which are inhibited by said each drug.

5. The method of claim 2, wherein a positive number is added to a standard baseline phenotype score if a patient is 65 years of age or older.

6. The method of claim 2, wherein, with dosages greater than 115% of average starting dose, per drug label, the standard baseline phenotype score is adjusted by adding a positive number and with dosages less than 85% of average daily dose, per drug label, the standard baseline phenotype score is adjusted by adding a negative number.

7. The method of claim 1, wherein steps 2 through 7 are performed automatically in a programmed computer.

8. A method of treating a patient with multiple drugs, comprising: 1) Obtaining tissue or fluid from a patient and analyzing the tissue or fluid for CYP450 enzyme genotypes; 2) converting the CYP450 enzyme genotypes to standard baseline phenotypes used to designate a given patient's ability to metabolize drugs for each CYP450 enzyme; 3) providing a numerical score for each standard baseline phenotype wherein the standard baseline phenotypes range from poor to intermediate to normal to rapid to ultrarapid and wherein the standard baseline phenotype scores increase in amount negatively from normal to ultra rapid and wherein the standard baseline phenotype scores increase in amount positively from normal to poor; 4) identifying whether each of said multiple drugs is a strong, medium, or weak inducer or a strong, moderate, or weak inhibitor of each of the CYP450 enzymes; 5) for each drug that is an inducer adding a negative number, increasing in amount from a weak inducer to a strong inducer, to the standard baseline phenotype scores for the CYP450 enzymes which are induced by said each drug, and for each drug that is an inhibitor adding a positive number, increasing in amount from a weak inhibitor to a strong inhibitor, to the standard baseline phenotype scores for the CYP450 enzymes which are inhibited by said each drug, thereby obtaining a total adjusted phenotype score for each of the CYP450 enzymes which are induced or inhibited; 6) converting the adjusted phenotype scores to adjusted phenotypes for said CYP450 enzymes which are induced or inhibited; 7) identifying, for each CYP450 enzyme that has an adjusted phenotype, each of said multiple drugs that are substrates for said each CYP450 enzyme that has an adjusted phenotype; 8) determining risk of occurrence of adverse events with the use of each of said multiple drugs identified in step 7, the determining of said risk being based upon the adjusted phenotype of each CYP450 enzyme for which each of said multiple drugs is a substrate; and 9) adjusting the dose of each of said multiple drugs identified in step 7, the adjusting being based on the determination of said risk, and treating the patient with each of said multiple drugs having the adjusted dose.

9. The method of claim 8, wherein converting the adjusted phenotype scores to adjusted phenotypes for said CYP450 enzymes is performed using a CYP450 enzyme phenotype conversion scale with phenotypes ranging from poor to intermediate-poor to intermediate to normal-intermediate to normal to rapid-normal to rapid to ultrarapid-rapid to ultrarapid and wherein phenotype scores for the phenotypes in the conversion scale increase in amount negatively from normal to ultrarapid and wherein the phenotype scores for the phenotypes in the conversion scale increase in amount positively from normal to poor.

10. The method of claim 8, wherein a positive number is added to a standard baseline phenotype score if a patient is 65 years of age or older.

11. The method of claim 8, wherein, with dosages greater than 115% of average starting dose, per drug label, the standard baseline phenotype score is adjusted by adding a positive number and with dosages less than 85% of average daily dose, per drug label, the standard baseline phenotype score is adjusted by adding a negative number.

12. The method of claim 8, wherein steps 2 through 7 are performed automatically in a programmed computer.

13. A method of treating a patient with multiple drugs, comprising: 1) Obtaining tissue or fluid from a patient and analyzing the tissue or fluid for CYP450 enzyme genotypes; 2) converting the CYP450 enzyme genotypes to standard baseline phenotypes used to designate a given patient's ability to metabolize drugs for each CYP450 enzyme; 3) providing a numerical score for each standard baseline phenotype wherein the standard baseline phenotypes range from poor to intermediate to normal to rapid to ultrarapid and wherein the standard baseline phenotype scores increase in amount negatively from normal to ultrarapid and wherein the standard baseline phenotype scores increase in amount positively from normal to poor; 4) adding a positive number to a standard baseline phenotype score if a patient is 65 years of age or older and with dosages greater than 115% of average starting dose, per drug label, adjust a standard baseline phenotype score by adding a positive number and with dosages less than 85% of average daily dose, per drug label, adjust a standard baseline phenotype score by adding a negative number. 5) identifying whether each of said multiple drugs is a strong, medium, or weak inducer or a strong, moderate, or weak inhibitor of each of the CYP450 enzymes; 6) for each drug that is an inducer adding a negative number, increasing in amount from a weak inducer to a strong inducer, to the standard baseline phenotype scores for the CYP450 enzymes which are induced by said each drug, and for each drug that is an inhibitor adding a positive number, increasing in amount from a weak inhibitor to a strong inhibitor, to the standard baseline phenotype scores for the CYP450 enzymes which are inhibited by said each drug, thereby obtaining a total adjusted phenotype score for each of the CYP450 enzymes which are induced or inhibited; 7) converting the adjusted phenotype scores to adjusted phenotypes for said CYP450 enzymes which are induced or inhibited, wherein converting the adjusted phenotype scores to adjusted phenotypes for said CYP450 enzymes is performed using a CYP450 enzyme phenotype conversion scale with phenotypes ranging from poor to intermediate-poor to intermediate to normal-intermediate to normal to rapid-normal to rapid to ultrarapid-rapid to ultrarapid and wherein phenotype scores for the phenotypes in the conversion scale increase in amount negatively from normal to ultrarapid and wherein the phenotype scores for the phenotypes in the conversion scale increase in amount positively from normal to poor; 8) identifying, for each CYP450 enzyme that has an adjusted phenotype, each of said multiple drugs that are substrates for said each CYP450 enzyme that has an adjusted phenotype; 9) determining risk of occurrence of adverse events with the use of each of said multiple drugs identified in step 8, the determining of said risk being based upon the adjusted phenotype of each CYP450 enzyme for which each of said multiple drugs is a substrate; and 10) adjusting the dose of each of said multiple drugs identified in step 8, the adjusting being based on the determination of said risk, and treating the patient with each of said multiple drugs having the adjusted dose.

14. The method of claim 13, wherein steps 2 through 8 are performed automatically in a programmed computer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 is flow chart describing the steps of the method of the present invention of obtaining adjusted phenotypes of CYP450 drug metabolizing enzymes for risk assessment of adverse drug reactions in multidrug dosing in patients.

[0017] FIG. 2 is a diagram of a computer system that may be used to implement the method of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0018] While the following description details the preferred embodiments of the present invention, it is to be understood that the invention is not limited in its application to the details of method illustrated in the accompanying figure and tables, since the invention is capable of other embodiments and of being practiced in various ways.

[0019] In the treatment of a patient with several drugs at one time, side effects and toxicity can occur in the patient as a result of one or more of the drugs reducing or inhibiting metabolism of another of the drugs. On the other hand, one or more of the drugs may induce or accelerate metabolism of another of the drugs so that the drugs may not exert its therapeutic effect. The drug metabolizing enzyme phenotypes of a patient can be measured and can be categorized as to the rate of metabolism of drugs as extensive, slow, very slow, fast, or very fast. A physician uses these patient phenotype categories to estimate the risk of an adverse or unwanted effect of the drug occurring. Based on the patient's phenotypes for drug metabolizing enzymes and on the information supplied by the drug manufacturer as to which drug enzymes metabolize a specific drug, the physician can increase or decrease the recommended dose of a drug or choose an alternative drug without the associated risk of adverse events. This approach of adjusting the dose of the drug is effective in preventing an adverse drug reaction. However, when several drugs are administered at one time to a patient the drug metabolizing enzyme phenotypes may be altered or express a different phenotype than innate phenotype, and the physician can no longer rely on the measured drug metabolizing enzyme phenotypes of the patient to estimate a proper dosage. The present invention solves this problem by providing an estimation method of adjusting the drug metabolizing enzyme phenotypes (current expression) based upon what is known about the pharmacogenetic effects of drugs on drug metabolizing enzymes (Pharmacokinetics). The physician can rely on the adjusted phenotypes (current expression) to assess risk of adverse drug reactions and to adjust dosage quickly.

[0020] Table 1 lists the standard phenotypes assigned to a given CYP450 enzyme. Numeric values are assigned to each phenotype. The values increase in amount negatively going from normal to ultra-rapid. The values increase in amount positively going from normal to poor. The process of aging can decrease drug metabolizing (hepatic) activity, so the score (expression) can be adjusted by adding the appropriate age factor amount to the score. For example, a person with an intermediate phenotype of a given CYP450 enzyme would have a score of 0.35 for that enzyme. If that person was 70 years old the score should be corrected by adding 0.05 to the score to give a score of 0.40, thereby factoring the increased risk of decreased genetic drug metabolic enzyme expression due to age and decrease in liver function as one ages.

TABLE-US-00001 TABLE 1 Assigning a Score to Standard CYP450 Enzyme Phenotypes Age Factor Phenotype Score Low High Factor UltraRapid 0.70 0 65 0.00 Rapid 0.40 65 75 0.05 Normal 0.00 75 120 0.10 Intermediate 0.35 Poor 0.70

[0021] Table 2 lists adjustments to the phenotype score for any drug that induces drug enzyme metabolizing activity for a given CYP450 enzyme. A drug that is an inducer of one or more CYP450 enzymes is characterized as a strong, moderate, or weak inducer of the enzyme. Strong, moderate, and weak are scored in increasing negativity from weak to strong. If there are more drugs that are inducers being given to the patient then the degree of negativity is increased for each category of weak, moderate, or strong for each additional drug that is an inducer. For example, if there are five drugs being given to a patient that are all weak inducers of the same CYP450 enzyme, then the score for that enzyme is adjusted by adding 0.90, based on Table 2.

TABLE-US-00002 TABLE 2 Adjustment to Phenotype Based on Degree of Enzyme Induction by a Drug Inducer Factor Drug # Strong Mod Weak 0 0.00 0.00 0.00 1 0.25 0.16 0.10 2 0.58 0.38 0.20 3 0.90 0.60 0.30 4 0.90 0.67 5 0.90

[0022] Table 3 lists adjustments to the phenotype score for any drug that inhibits drug enzyme metabolizing activity for a given CYP450 enzyme. Certain CYP 450 enzymes are less or more susceptible to inhibition based on a size of pathway. 3A4, 2C9 and 1A2 have many more enzymes available for a drug, whereas 2C19, 2B6 and 2D6 have fewer enzymatic sites and are impacted greater by inhibition. This is reflected in Table 3 and explains why each CYP450 enzyme has it's own table for inhibition and induction effect. A drug that is an inhibitor of one or more CYP450 enzymes is characterized as a strong, moderate, or weak inhibitor of the enzyme. Strong, moderate, and weak are scored in increasing positivity from weak to strong. If there are more drugs that are inhibitors being given to the patient then the degree of positivity is increased for each category of weak, moderate, or strong for each additional drug that is an inducer. For example, if there are three drugs being given to a patient that are all moderate inhibitors of the same CYP450 enzyme, then the score for that CYP450 enzyme is adjusted by adding 0.65, based on Table 3.

TABLE-US-00003 TABLE 3 Adjustment to Phenotype Based on Degree of Enzyme inhibition by a Drug Inhibitor Factor Drug # Strong Mod Weak 0 0.00 0.00 0.00 1 0.37 0.20 0.10 2 0.63 0.41 0.22 3 1.00 0.65 0.40 4 1.00 0.67 6 1.00

[0023] Each drug may interact with more than one CYP450 drug metabolizing enzyme. A drug may be a substrate for one CYP450 enzyme, an inducer of another CYP450 enzyme, and an inhibitor of yet another CYP450. One can understand that administering four or five drugs to a patient would involve complex calculations that are not feasible to perform in a clinical situation in which a physician wishes to adjust doses to avoid serious adverse drug reactions. The physician cannot rely on the standard CYP450 phenotypes for the various CYP450 enzymes involved because the CYP450 phenotypes may all be altered and expressed differently from normal by the combination of the drugs. The present invention provides a practical and useful way to overcome this problem.

[0024] Once the scores for the CYP-450 drug metabolizing enzymes have been adjusted as described above and a new score for each CYP-450 drug metabolizing enzyme has been calculated, then the score is converted to a new phenotype, i.e., and adjusted phenotype. Table 4 provides a look up table as an example of a way to look up an adjusted phenotype from an adjusted score.

[0025] Preferably, the phenotype categories are expanded to provide more precision in the estimate of phenotype and to expand the range of risk associated with the phenotypes. Between the poor and intermediate categories is intermediate-poor. Between intermediate and normal is normal-intermediate. Between normal and rapid is rapid-normal. Between rapid and ultrarapid is ultrarapid-rapid. Instead of a single score being given for each phenotype designation, a range of scores is given. Once an adjusted phenotype score is obtained, a table of values such as those shown in Table 4 can be used to convert the adjusted phenotype score to an adjusted phenotype. Thus, if a specific CYP450 enzyme had an adjusted phenotype score of 0.61, then the adjusted phenotype for that CYP450 enzyme would be intermediate-poor. Any of the drugs that are metabolized by that enzyme might have a risk of increased adverse events. A provider can quickly identify the drugs affecting the CYP450 pathway expression and increasing the risk of adverse events; just as the provider can in the case where only a single drug is administered.

TABLE-US-00004 TABLE 4 Adjusted Phenotype Lookup Adjusted Phenotype Low High UltraRapid 10.00 0.65 UltraRapid-Rapid 0.64 0.52 Rapid 0.51 0.33 Rapid-Normal 0.32 0.16 Normal 0.15 0.15 Normal-Intermediate 0.16 0.36 Intermediate 0.37 0.51 Intermediate-Poor 0.52 0.69 Poor 0.70 10.00

[0026] FIG. 1 illustrates the steps of the method of the present invention for treating a subject with multiple drugs. Blood or saliva is obtained from a subject and analyzed for CYP450 enzyme genotypes by methods well known in the art. The enzymes are, preferably, 3A4, 3A5, 1A2, 2C9, 2B6, 2C19, 2C8 and 2D6. The genotype for each CYP450 enzyme is converted to a baseline standard phenotype which is used to designate a given subject's ability to metabolize drugs for a given CYP450 enzyme, as is known in the art (Step 1). A numerical score is provided for each baseline standard phenotype for CYP450 enzymes wherein the phenotypes range from poor to intermediate to normal to rapid to ultra-rapid and wherein the scores increase in amount negatively (faster metabolism) from normal to ultra-rapid and increase in amount positively (slower metabolism) from normal to poor (Step 2).

[0027] For each drug to be administered to the patient the CYP450 enzymes are identified for which each drug is a substrate. Each drug is identified as to whether the drug is a strong, moderate, or weak inducer or a strong, moderate, or weak inhibitor of each of the CYP450 enzymes (Step 3). For each drug that is an inducer a negative number is added, increasing in amount from a weak inducer to a strong inducer, to the baseline phenotype scores for the enzymes which are induced, to adjust the phenotype scores (Step 4). For each drug that is an inhibitor a positive number is added, increasing in amount from a weak inhibitor to a strong inhibitor, to the baseline phenotype scores for the enzymes which are inhibited, to adjust the phenotype scores (Step 5). Patient age is identified, and a positive number is added to the phenotype score if, for example, the patient is 65 years of age or older Step 6).

[0028] With dosages greater than 115% of average starting dose per drug label the phenotype score is adjusted with positive number added. With dosages less than 85% of average daily dose per drug label the phenotype score is adjusted with a negative number added (Step 7). These dose related adjustments are based on clinical findings that inhibition, induction and substrate risk are increased or decreased based on the amount of drug ingredient prescribed. In other words, a drug that is a weak inhibitor of CYP pathway A in larger dosages than normal will inhibit at a greater strength than at a weaker strength and further adjust phenotypical expression to the slower (more positive score) phenotype while increasing the risk of needing a dose adjustment (an increased dose).

[0029] The results of steps 4 through 7 are combined to provide a total adjusted phenotype score. The total adjusted phenotype score is converted to an adjusted phenotype using, for example, a table such as Table 4 (Step 8). The risk of occurrence of adverse events from the use of the drugs which are substrates for enzymes having an adjusted phenotype are assessed, using the adjusted phenotype to make the assessment (Step 9). The drug amounts for dosing can adjusted based on the adjusted phenotypes, a prescription for the adjusted drug amounts can provided to the patient, and the patient can be treated with the adjusted drug amounts (Step 10).

[0030] This method of adjusting patient phenotypes of CYP450 drug metabolizing enzymes can be implemented in a computer or processor using standard software programs and algorithms. Such software programs implementing this method can be sold and/or licensed to drug prescribers, related personnel, and the like (users) for a fee. Alternatively, a user can access a website of a provider of this method and can, for a fee, access a program that will allow the user to input information such as patient age, drugs being prescribed, and the genotypes of the CYP450 enzymes for that patient.

EXAMPLE 1

[0031] A patient age 68 is to receive metoprolol, paroxetine, diltiazem, Irbesartan, and glyburide. The patient's physician obtains a sample of blood or saliva from the patient and obtains a pharmacogenetic analysis of the patient's genotype for CYP450 enzymes 2D6, 2C9, 3A4, and 2C19. Based on the genotype results the phenotypes for the enzymes were 2D6=normal; 2C9=intermediate; 3A4=normal; and 2C19=normal. The user enters the patients age, drugs to be prescribed, and the enzyme phenotypes into a program that performs steps of the present invention. The program calculates a starting (baseline) phenotype score, adds a correction for age, searches one or more drug databases and finds that metoprolol is a substrate for 2D6, paroxetine is a substrate for 2D6 and strong inhibitor of 2D6, Diltiazem is a substrate for 3A4 and a weak inhibitor of 2D6, Irbesartan is a substrate for 2C9, and glyburide is a substrate for 2C9. Scoring and calculations are made as follows, as described for Tables 1-4:

TABLE-US-00005 Scores Baseline Baseline Total Adjusted Phenotype Enzyme Phenotype Score Age Inducer Inhibitor score based on total score 2D6 normal 0 0.05 0 0.37 + 0.1 0.52 intermediate poor 2C9 intermediate 0.35 0.05 0 0 0.40 intermediate 3A4 normal 0 0.05 0 0 0.05 normal 2C19 normal 0 0.05 0 0 0.05 normal

[0032] The phenotype for the 2D6 enzyme is adjusted from normal to intermediate poor. The other phenotypes are not altered. A user can readily see that there is a significant risk with the drugs that are substrates for the 2D6 enzyme which are metoprolol and paroxetine. With the drug combination in this example metoprolol and paroxetine may be metabolized to a lesser degree than normal. The result could be toxicity related to abnormally high blood levels of these drugs. The adjusted phenotypes produced by the method of this invention provide reliable phenotypes for a user to make decisions on drug dosage, such as making changes in dose or making substitutions of the drugs.

EXAMPLE 2

[0033] A patient age 46 is to receive Depakote, Prozac, Zyprexa, Abilify, Haldol, Benadryl, Lexapro and Risperdal. Pharmacogenetics testing revealed the following phenotypes for the CYP450 enzymes: 2B6=intermediate, 2C19=ultrarapid, 2D6=poor; 3A5=poor; 2C9=normal; and 3A4=normal. The user enters the patient's age, drugs to be prescribed, and the enzyme phenotypes into a computer program that performs steps of the present invention. The program calculates a starting (baseline) phenotype score and searches one or more drug databases and finds that Depakote is a substrate for 2C9 and 2B6, Prozac is a substrate for 2C9 and 2D6, Zyprexa is a substrate for 1A2 and 2D6, Abilify is a substrate for 2D6 and 3A4, Haldol is a substrate for 2D6 and 3A4, Benadryl is a substrate for 2D6, Lexapro is a substrate for 2C19 and 3A4; and Risperidone is a substrate 2D6 and 3A4. The search further finds that Depakote is a weak inhibitor of 2C9, 2C19 and 3A4, Prozac is a moderate inhibitor of 2C9 and 2C19, a strong inhibitor of 2D6, and a weak inhibitor of 3A4, Haldol is a weak inhibitor of 2D6; Benadryl is a weak inhibitor of 2D6; Lexapro is a weak inhibitor of 2D6; and risperidone is a weak inhibitor of 2D6. Scoring and calculations are made as follows, as described for Tables 1-4:

TABLE-US-00006 Scores Baseline Baseline Inhibitor Total Adjusted Phenotype Enzyme Phenotype Score weak moderate strong score based on total score 2B6 intermediate 0.35 0 0 0 0.35 intermediate 2C19 ultrarapid 0.70 0.10 0.20 0 0.4 rapid 2D6 poor 0.70 0.67 for 4 0 0.37 1.74 poor 3A5 poor 0.70 0 0 0 0.70 poor 2C9 normal 0.00 0.10 0.2 0 0.30 normal-intermediate 3A4 normal 0.00 0.22 for 2 0 0 0.22 normal-intermediate

[0034] The phenotypes for 2C9, 3A4, and 2C19 were adjusted. Depakote and Prozac are substrates for 2C9. The adjustment from normal to normal-intermediate for 2C9 would indicate an increased risk of side effects with Depacote and further increased risk of adverse events with Prozac. Abilify, Haldol, and Resperdal are substrates for 3A4. The adjustment of 3A4 from normal to normal-intermediate would indicate an increased risk of adverse events with these drugs. Lexapro is a substrate for 2C19 and 3A4. The adjustment of 2C19 from ultrarapid to rapid and 3A4 from normal to normal-intermediate would indicate that Lexapro may not be metabolized as it would be in the absence of the other drugs but the adjusted phenotype for 2C19 to only rapid would suggest a risk still of under dosing with Lexapro and not achieving a therapeutic response. With regard to 2D6, even if the patient had a normal phenotype for 2D6, the four weak inhibitors of 2D6 and the one strong inhibitor of 2D6 would still render the phenotype poor. The total score for 2D6 would be 1.04 (0.67 +0.36), still within the range of poor (see Table 4). Even if the phenotype for 2D6 was normal, the method of adjusting the phenotype of the present invention would predict a risk of adverse events with the combination of drugs in this example.

[0035] This method of adjusting phenotypes can be implemented as a computer program in any standard computer/processor system well known in the art. A service provider can provide the software to implement the method. FIG. 2, for example, illustrates a user's computer 10 having a processor 11, memory 12, a user interface 13, display, and a power supply 15. The computer 10 may be connected to a service provider's server 16 through the internet 17. All that is required is an entry by the user 11 into the computer 10 through interface 13 of the names of the drugs to be administered to a patient and the measured genotypes of the CYP450 drug metabolizing enzymes. The age of the patient can also be entered along with any other factors that affect drug metabolism. This information is transmitted to a service provider's server 16, for example, through the internet 17. Within seconds, adjusted phenotypes can be provided by the service provider's server 16 to the user's computer 10. The adjusted phenotypes can be retrieved from the user's computer 10 by methods well known in the art. The service provider's software and server 16 retrieve all the necessary data to make calculations of adjusted phenotypes for the user. A user can then use the adjusted phenotypes to quickly estimate the risk of an adverse drug event occurring with any of the drugs to be administered. The dosages of the drugs to be administered are then adjusted based on the adjusted phenotypes and prescribed to the patient.

[0036] This method of adjusting phenotypes uses databases that identify all medications influenced by CYP450 interactions. These databases include: [0037] Elsevier https://www.elsevier.com/solutions/clinical-pharmacology; [0038] Elsevier Gold Standard: https://www.elsevier.com/promo/clinical-solutions/drug-information?; [0039] PharmGKB: https://www.pharmgkb.org/; [0040] CPIC Guidelines and Drug Bank: https://cpicpgx.org/guidelines/; [0041] Epocrates/Athena https://landing.athenahealth.com/epocrates-clinicals?; and [0042] PharmVAR https://www.pharmvar.org/.
The databases provide the CYP450 enzymes for which all the drugs are substrates and describe for each drug whether the drug is a weak, moderate, or strong inducer or inhibitor of any CYP450 enzyme.

[0043] This method of adjusting phenotypes has been validated by analyzing and interpreting data from over 50,000 patients who received multiple drug therapy (polypharmacy) and who had pharmacogenetic testing for CYP450 genotypes. The values used herein to calculate adjusted phenotypes provide accurate CYP450 drug metabolizing enzyme phenotypes to make accurate risk assessment of adverse events occurring with multi-drug therapy. Because the method can be implemented in a computer adjusted phenotypes can be provided to a user quickly.

[0044] The foregoing description has been limited to specific embodiments of this invention. It will be apparent, however, that variations and modifications may be made by those skilled in the art to the disclosed embodiments of the invention, with the attainment of some or all of its advantages and without departing from the spirit and scope of the present invention. For example, the method can be used to determine if an alternate drug with less effects on drug metabolism can replace another drug. The method can be used for any drug metabolizing enzyme that has been identified and characterized with regard to drug metabolism. Scoring can be in any desired form as long as it reflects changes in phenotype. The method can be used for multiple drug dosing in non-human subjects, such as dogs, cats, farm animals, etc.

[0045] It will be understood that various changes in the details, materials, and methods which have been described above in order to explain the nature of this invention may be made by those skilled in the art without departing from the principle and scope of the invention as recited in the following claims.