Overwhelmed by side effects

CASE: Medication sensitivity

Mrs. C, age 48, is admitted to a tertiary care inpatient mood disorder unit for evaluation of severe depression characterized by depressed mood, anhedonia, and insomnia. Her initial Hamilton Rating Scale for Depression 17-Item (HRSD-17) score is 30, indicating severe depression. Her medications are fluoxetine, 10 mg/d, and diazepam, 0.5 mg/d.

Mrs. C describes a 10-month history of depression and extreme anxiety in the context of several psychosocial stressors. Her father recently died and she is having difficulty with the demands of administering her father’s estate. She is intensely obsessive and focused on nihilistic themes, her diagnosis, somatic themes, and medications side effects. Her husband confirms our observations. No history or current symptoms of typical compulsions (eg, washing hands or checking doors) are elicited. She has limited insight into her obsessive tendencies.

Mrs. C had no psychiatric history before her depressive and obsessive symptoms developed 10 months ago. However, in the past 10 months, she has been hospitalized in a psychiatric facility twice. She also received a series of 8 electroconvulsive therapy treatments, but reported minimal improvement of her depressive symptoms. Mrs. C had a few cognitive-behavioral therapy (CBT) sessions with a psychotherapist, but she said they didn’t help much.

Mrs. C has substantial difficulty adhering to medications, even at subtherapeutic doses. She states she is “extremely sensitive” to all medications. Mrs. C says she develops dizziness, increased anxiety, insomnia, nausea, and other vague reactions whenever she attempts to increase her psychotropics to therapeutic doses. She took sertraline, 10 mg/d, for 4 days, but discontinued it because of unspecified side effects. She then received escitalopram, 2.5 mg/d, for 10 days, but again stopped it because of vague side effects. She was taking paroxetine, 10 mg/d, for 2 days, but experienced vomiting and discontinued the drug. She tried venlafaxine at a low dose and also discontinued it because of vomiting. Mrs. C stayed on mirtazapine, 22.5 mg/d, for 3 months, but stopped it because of lack of efficacy and she was unwilling to increase the dose. Other unsuccessful trials include citalopram and doxepin. Mrs. C is hesitant to try another medication or increase to therapeutic doses any of the previous medications.

The authors’ observations

Before initiating another treatment, the treatment team considered Mrs. C’s pervasive medication intolerance. Her enzymatic activity may be genetically compromised, which could lead to high blood levels of medications and significant side effects when she takes very low doses. Individual variations in response to psychotropics are influenced by genetic factors.¹ Variants in the cytochrome P450 (CYP450) genes produce enzymes with increased activity, normal activity, reduced activity, or no activity, creating phenotypes of ultrarapid metabolizers, extensive metabolizers, intermediate metabolizers, and poor metabolizers, respectively. These genetic variations can affect blood levels of medications that employ these enzymes in their metabolic pathways.² Mrs. C could be a poor metabolizer of common CYP450 variant enzymes, which led to her exquisite sensitivity to psychotropics. We felt this was a reasonable hypothesis given her tumultuous 10-month course of psychiatric treatment and multiple failed medication trials.

An alternative hypothesis is that Mrs. C’s somatic obsessions about drug side effects were the primary clinical issue that led to her severe medication intolerance. Mrs. C spends hours questioning the inpatient staff about her diagnosis (eg, “Are you sure I don’t have bipolar disorder?”), medications (eg, “Are you sure this medication won’t make me sick?”), somatic themes (eg, “Are you sure I don’t have Meniere’s disease with all my dizziness?”), and nihilistic themes (eg, “What if I never get better?”). Mrs. C’s husband attested that she has spent hours researching her new medications on the Internet and reading the medication handouts from the pharmacy. She admits to mentally cycling through the DSM-IV-TR criteria for hours at a time to “figure out” if she has bipolar disorder (BD).

We initiated pharmacogenomic testing to help distinguish between these hypotheses. Mrs. C’s results are presented in Table 1. Genotype results were applied using an interpretive algorithm (Figure) in which 26 psychiatric medications were placed in categories of “use as directed” (green column), “use with caution” (yellow column), and “use with caution or more frequent monitoring” (red column). The algorithm incorporates the genetic information with the known pharmacologic profile for each of the medications in the panel. Highlights of Mrs. C’s interpretive report are shown in Table 2.

Table 1

Mrs. C’s genotype results