What is Pharmacogenomics Testing?

Pharmacogenomics, also referred to as Pharmacogenetics, is a genetic test for drug response. This is not a new field of study, although it has gained traction in recent years. First explored in the 1950’s, pharmacogenetics testing is a type of genetic variability testing that can help medical professionals create a more personally tailored approach to medication. This type of test can analyze each person’s individual genetic makeup to determine how they may metabolize specific medications and help avoid potentially dangerous reactions.

One swab from each cheek from a patient can help determine:

       •Whether or not a certain medication will be effective for them

       •What dose of medication will work for them

       •Whether or not they will experience serious side effects

Both terms, Pharmacogenomics and Pharmacogenetics, describe the study of human genes and how they affect the body’s response to medications. “Pharmacogenomics” is a combination of the words pharmacology, which is the study of medications, and genomics, which is the study of genes.

Pharmacogenomics testing is quickly becoming more common in the world of medical care, as it could save lives, as well as millions of dollars in healthcare costs from those who experience adverse reactions to medications. Although there are different Pharmacogenomics tests for different medications, each person would only need to be tested once since a person’s genetic makeup does not change over time.

LTC Ventures contracts with a number of different labs to fit the needs of the patient, physician, healthcare facility, and pharmacy. All labs are not the same. We’ve partnered with the best labs in the industry based on in network coverage, reporting, service, and integrity.

Which patients should be tested and why? The testing has been significant in detecting drug-drug and drug-gene interactions in a number of areas. The concentrated areas that are currently covered are based around cardio and physiological diagnoses. 

Not everyone reacts the same to medications. How a medication works in each person is dependent on a variety of factors which can be difficult, if not impossible, to determine before taking a medication. Some people may have mutations in their bodies that make certain medications too strong and potentially dangerous.

Adverse reactions to medications is the 4th leading cause of death. According to US Food and Drug Administration statistics, over two million adverse drug events occur annually. Certain drugs now include warnings regarding metabolizer ability in the packaging or labeling.

Patients currently undergo a “trial and error” approach to finding what medication will work for them. This can lead to death, or long periods of discomfort and even pain as they try to adjust. The use of Pharmacogenomics testing is used to eliminate these occurrences.

Common Adverse Reactions to Medications

There are also cases in which people have experienced severe side effects from prescribed medications, including seizures, heart failure, and even death.

  • Headaches or migraines       

  • Rash

  • Fever

  • Dizziness

  • Joint and muscle pain

  • Fatigue

  • Hallucination

  • Irritability

  • Nausea

  • Constipation

  • Diarrhea

  • Vomiting

 

On the opposite end of the spectrum, some medications simply don’t work for certain people. They don’t have any reaction or feel any effect from the medication at all. Sometimes, a medication will work briefly, and then the effects die off after a few days.

Medication & The Risk of Falls in the Elderly

Polypharmacy is an independent risk factor for falls.

Patients on FOUR or more medicines are at greater risk of having a fall. Regular medication reviews play an important part in falls prevention.

Psychotropic drugs are those most clearly implicated in falls especially tricyclic antidepressants, antipychotics & benzodiazepines.

They should be used for specific indications for the minimum time necessary.

Benzodiazepines & other hypnotics increase the risk of falling in a dose dependent way.

Even if gradual withdrawal is not an achievable goal, a reduction in falls risk is still gained from dose modification. For those who have difficulty withdrawing, switching to an equivalent dose of diazepam followed by dosage reductions in small steps is suggested (see BNF).

▹Hypotension is recognized as a key contributing factor to falls.

Orthostatic hypotension (OH) due to concomitant drugs commonly occurs. Symptomatic OH e.g. postural dizziness is likely to be a better predictor of falls risk than defined on BP criteria alone. To screen for postural hypotension LYING & STANDING blood pressures should be performed. (OH is defined as a drop in systolic BP>20mm Hg or diastolic BP > 10mmHg).

A good intervention for low blood pressure (in the absence of any signs of arterial disease e.g. intermittent claudication) is the use of compression hosiery to increase venous return.

The risk of having a fall or recurrent falls increases with the number of associated intrinsic risk factors below:

  • previous fall - polypharmacy ie 4 or more drugs - alcohol >1 unit/day

  • poor mobility/ gait - psychotropic drug use - orthostatic hypotension

  • balance disorders - visual impairment - hearing impairment

  • cognitive impairment

Patients with 4 or more risks factors identified above are at the greatest risk of having a fall.

There is clear evidence to show Calcium and Vitamin D supplementation reduces the risk of falls in ambulatory or institutionalized older people.

▹Daily supplementation of 1-1.2g Calcium (Ca) in combination with at least 800IU vitamin D as colecalciferol has been shown to improve both body sway and muscle function in elderly individuals, reducing overall falls risk by more than 20%. Supplementation should be considered in all older people aged 65 years or over who are either housebound, live in residential / nursing home accommodation, have a BMI < 19kg/m2 or have 4 or more risk factors as identified above. NNT to prevent one fall =15. Recommended Ca & vitamin D supplements available to prescribe: Chewable Formulations - AdCal D3; Calceos; Calcichew D3 Forte. Dose = 2 tablets daily. Dispersible Formulations - Cacit D3 (2 sachets daily) & Calfovit D3 (1 sachet daily).

NB. Patients also on thiazide diuretics should have U&E’s & serum Ca regularly monitored.

▹_ There is NO ‘safe’ dose of oral glucocorticoids in reducing fracture risk.

The administration of oral glucocorticoids is associated with a significant increase in fracture risk at the hip and spine. Although the greatest increase in risk is observed with higher dose therapy, increased fracture risk is seen even at daily doses less than 7.5mg. All older people with a either a previous fragility fracture, evidence of kyphosis, taking long term oral prednisolone 27.5mg /day or treated with intermittent oral glucocorticoids at doses 27.5mg /day for 3 months or more should be on bisphosphonate therapy in addition to Ca & Vitamin D supplementation (ref RCP Gio Scope audit guidelines). Measurement of bone density is not required before starting treatment.

MODERATE RISK DRUGS

ACE inhibitors / Angiotensin

II antagonists

Risk of hypotension is potentiated by concomitant diuretic use. Incidence of dizziness varies from 4-12% of patients but affects twice as many patients with heart failure than hypertension.

 

Alpha – blockers

Doses used for treatment of BPH less likely to cause hypotension than those required to treat hypertension.

 

Anti-arrhythmics

Dizziness and drowsiness are possible signs of Digoxin toxicity – risks of toxicity greater in renal impairment or in the presence of hypokalaemia. Flecainide has a high risk for drug interactions and can also cause dizziness.

 

Anti-epileptics

Group with high risk for potential drug interactions. Incidence of dizziness drowsiness and blurred vision are dose related side effects observed with Carbamazepine but may be reduced by altering timing or choice of formulation. Phenytoin side effects such as dizziness blurred vision etc. may be signs of drug related toxicity.

 

Anti-histamines

Somnolence may affect up-to 40% of patients with older antihistamines e.g. Chlorpheniramine. The newer anti-histamines e.g. Desloratidine cause less sedation and psychomotor impairment. Risk of hypotension with Cinnarizine is a dose related side effect.

 

Beta-blockers

Reports of dizziness may be due to postural hypotension and can affect up to 10% of patients. Water-soluble beta-blockers can accumulate in renal impairment and therefore dose reduction is often necessary.

 

Diuretics

Postural hypotension, dizziness and nocturia are the most frequent problems seen in the elderly. Diuretics should not be prescribed for long-term use in the treatment of gravitational edema.

 

Opiate analgesics

Drowsiness and sedation common with initiation of treatment but tolerance to these side effects is usually seen within 2 weeks of continuous treatment. Drowsiness and sedation is rare with Codeine unless concurrently used in combination with other drugs with CNS effects. Confusion also reported with Tramadol.

LOW RISK DRUGS

Calcium Channel Blockers

Incidence dizziness low especially for once daily dihydropyridone calcium channel blockers e.g. Felodipine

 

Nitrates

Dizziness may be due to postural hypotension. Advise patient to sit when using GTN spray or tablets

 

Oral anti-diabetic drugs

Dizziness due to hypoglycaemia but usually avoidable. Avoid long acting sulphonylureas e.g. Chlorpropamide.

 

Proton Pump Inhibitors

(PPIs) & H2 Antagonists

Avoid Cimetidine in polypharmacy patients – high risk of potential drug interactions. Cimetidine also associated with causing confusion in the elderly. Reports of dizziness, somnolence are uncommon and mental confusion or blurred vision rare with the other PPIs and H2 antagonists.

IMPROVING PATIENT OUTCOMES

Pharmacogenomics has the potential to provide tailored drug therapy based on genetically determined variation in effectiveness and side effects. This will mean:

More powerful medicines - Pharmaceutical companies will be able to produce therapies more targeted to specific diseases, maximizing therapeutic effects while decreasing damage to nearby healthy cells.

Better, safer drugs the first time - Recovery time will go down and safety will go up as the likelihood of adverse reactions goes down or is eliminated altogether.

▹More accurate methods of determining appropriate drug dosages - Current methods of basing dosages on weight and age will be replaced with dosages based on a person's genetics --how well the body processes the medicine and the time it takes to metabolize it.

PHARMACIST ROLE IN PHARMACOGENOMICS

Pharmacists’ role in pharmacogenomics includes promoting the optimal use and timing of pharmacogenomics tests; interpreting clinical pharmacogenomics test results; and educating other pharmacists, fellow health care professionals, patients, and the public about the field of pharmacogenomics. The following areas should be part of any clinical pharmacogenomics service:   

 

▹Advocating for the rational and routine use of pharmacogenomics testing.

▹Providing test result interpretation and clinical guidance for return of results to providers and patients in collaboration with other health care professionals (e.g., physicians, laboratory professionals, and genetic counselors).

▹Optimizing medication therapy based on pharmacogenomics test results.

▹Educating and providing information on the clinical application of pharmacogenomics to health professionals, patients, and members of the public.

▹Supporting and participating in research, consortia, and networks that guide and accelerate the application of pharmacogenomics to clinical practice.

SUMMARY

▹Many factors influence drug safety and efficacy

▹Comprehensive report identifies significant risks across medication classes

 

▹Genotyping a patient for a single indication, drug, or gene is unlikely to reveal the patient’s true risk burden based on their co-morbidities and polypharmacy

▹Panel-based approach with drug-gene and drug-drug interactions improves sensitivity

  • ID high-risk drug, safer doses, and/or better alternatives

  • Different decisions 52% of the time resulting in improved outcomes and satisfaction in 67% of the cases

▹Include pharmacist in test results interpretation and physician interaction for optimal medication management therapy. Our Practitioners are very active in Pharmacogenomics testing.

SAMPLE REPORTS

LTC Ventures works with multiple labs. We have chosen these labs based on insurance network coverage, lab personnel access, and reporting. We have also used input from current customers, physicians, pharmacists, and nurse practitioners and their report preferences. If you would like to see sample reports, please contact us and we will send reports from multiple labs to help you determine which lab reporting you would like to see. We offer testing in Pharmacogenomics and Toxicology.  

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