UH is a 53 year old male who two months ago lost his wife who died due to breast cancer. His PMH is significant for hypertension, hyperlipidemia, and allergic rhinitis for which he takes lisinopril 20mg daily, atorvastatin 40mg daily, and allegra 180mg once daily. His vitals today in clinic are BP 135/80, HR 70, T 98.8 F, RR 12. He reports to his PCM a 6-week history of nightly insomnia, lack of energy, inability to concentrate at his job, a 15 pound weight loss, and overall feeling poor. He also espouses some recent anxiety about issues in his life that normally he has felt no worries about. His primary care provider is considering prescribing paroxetine for what is consistent with a major depressive disorder. Which of the following are true regarding paroxetine therapy for UH? Select all that apply.
A. While paroxetine may benefit some symptoms within the first two weeks, maximal benefit often takes up to 4-6 weeks to occur.
B. Paroxetine should never be stopped abruptly due to a potential for discontinuation syndrome.
C. The most common adverse effects in the initiation phase are gastrointestinal (nausea/vomiting/abdominal discomfort).
D. Paroxetine may inhibit metabolism of medication substrates that pass through CYP 2D6.
E. Paroxetine may benefit UH's anxiety if he is ultimately diagnosed with generalized anxiety disorder (GAD).
Answer with Rationale:
All answers are correct. SSRIs are one of the most prescribed medications in the United States, primarily for depression. While intended in most patients to be given for a short time, often they are given for much longer. UH due to the death of his wife hopefully can be given a short course and then taper off in 6-9 months. Answers A, B, and C are very important for patients to understand and know as these could lead to nonadherence. Paroxetine has the highest risk of discontinuation syndrome with fluoxetine having the lowest risk due to long metabolite half-life. While GI side effects can happen when initiated, they often abate quickly with continued therapy. Medications such as risperidone or tamoxifen, that are CYP 2D6 substrates, may be affected by coadministration with paroxetine. Fluoxetine also possesses significant 2D6 inhibition properties. Additionally, paroxetine also has an FDA-approved indication for Generalized Anxiety Disorder (GAD).
For more information on antidepressants, please see our chapter in the 3rd Edition Naplex Review Guide on AccessPharmacy edited by Dr. Scott Sutton: