Treating seniors for depression is very different than treating a younger population.

Seniors often face multiple diseases – which may mean multiple medications to manage. According to the National Center for Health Statistics, more than 89% of older people use at least one prescription and more than 68% use three or more prescriptions in any given month. Those statistics might not include over the counter (OTC) supplements or vitamins that they may be taking as well.

Taking multiple medications at the same time, or polypharmacy, can be problematic because often the patients are seeing various specialists for differing ailments. Since no single provider is typically responsible for managing the patient’s complete medication profile, drug/drug interactions could occur. To help effectively manage this issue, two guidelines have been published to assist physicians in making critical medication decisions.

Identifying Potentially Inappropriate Medications via the Beers Criteria

Since 2011, The Beers Criteria® has been regularly updated by the American Geriatrics Society to catalogue medications known to cause adverse drug reactions in elderly patients. By using evidence-based methodology, the Beers Criteria accounts for the pharmacologic properties of drugs in addition to the physiologic changes of aging.

Updated in January 2019, the AGS Beers Criteria describes Potentially Inappropriate Medications (PIMS) that have been documented with evidence, suggesting that they should either be:

1. Avoided by most older people (outside of hospice and palliative care settings);
2. Avoided by older people with specific health conditions;
3. Avoided in combination with other treatments because of the risk for harmful “drug-drug” interactions;
4. Used with caution because of the potential for harmful side effects; or
5. Dosed differently or avoided among people with reduced kidney function, which impacts how the body processes medicine

You can read more information on the updated AGS Beers Criteria for PIMS, which was recently published in the Journal of the American Geriatrics Society, here: DOI: 10.1111/jgs.15767.

Finding Alternatives via START/STOPP Criteria

START/STOPP Criteria is intended to be used in conjunction with the Beers Criteria.

START is an acronym for the Screening Tool to Alert doctors to the Right Treatment. STOPP stands for the Screening Tool of Older Persons’ Prescriptions.

Like the Beers Criteria, START/STOPP criteria lists the PIMS. Unlike the Beers Criteria, it also stratifies them by potentially inappropriate use and indication, documents the clinical concern, and lists recommended therapeutic alternatives.

Using Pharmacogenomics to Inform Medication Selection

There is a third uniquely individualized tool that may help healthcare providers – pharmacogenomics. Pharmacogenomic tests, like GeneSight® Psychotropic, can identify  genetic variations that may impact a patient’s medication response.

To illustrate how pharmacogenomics can be used in the elderly population, consider venlafaxine (Effexor^®) as an example. There are several CYP450 enzymes involved in breaking down venlafaxine to its metabolites. The most significant pathway is shown here, where venlafaxine is broken down into its active metabolite desvenlafaxine:

The most important enzyme in this pathway is CYP2D6. CYP2D6 poor metabolizers may have increased serum concentrations of venlafaxine compared to patients who are more efficient CYP2D6 metabolizers.

A study in the European Journal of Clinical Pharmacology detailed how researchers Waade and colleagues examined the effects of CYP2D6 phenotype status on serum drug concentrations of venlafaxine. They found that a patient’s CYP2D6 phenotype (or activity level) was associated with measured serum levels of venlafaxine. For example, in patients under 40 years of age, poor metabolizers had higher serum concentrations than intermediate metabolizers. In this study, intermediate metabolizers were called heterozygous extensive metabolizers (HEM) and had higher serum concentrations than extensive metabolizers.

As the chart below illustrates, in the poor metabolizer (PM) group, there is a difference in serum concentration between age groups. Venlafaxine serum concentration was more than 7 times higher in the elderly poor metabolizers than it was in poor metabolizers under the age of 40. As a result, elderly individuals who are poor metabolizers could experience a pronounced reduction in medication clearance.

Case Study and More from Our Series on Treating Depression in Seniors

The Beers criteria, the STOPP/START criteria, and the GeneSight test are just a few of the many tools that can help healthcare providers treat and manage multiple medications in the geriatric population.

Our webinar series has a number of videos devoted to treating depression in seniors, including an introduction to pharmacogenomics and a case study. The guidelines chalk talk and the  entire series is also available on our YouTube channel.