● Nausea, vomiting, and diarrhea. ● Panic attacks. ● Restlessness. ● Tinnitus. ● Vertigo. ● Rarely, hypomania or mania.
Dizziness is the most common adverse effect. Other common, mild adverse drug reactions include nasal congestion, headache, drowsiness, nausea, and diarrhea (Wilson & Tripp, 2021). These typically go away or weaken with time. Due to the drug’s dopamine antagonism, there is a rare risk for akathisia. Buspirone has strong affinity for serotonin 5HT1a receptors, and weak affinity for 5HT2 receptors (Wilson & Tripp, 2021). Monitor patients prescribed both buspirone and an SSRI for serotonin syndrome. The therapeutic dose range for buspirone is 15-60 mg/day (Wilson & Tripp, 2021). For treating GAD, the recommended initial dose is 7.5 mg twice a day or 5 mg three times a day. The daily dose may be increased in 5-mg increments every two or three days, up to a maximum daily dose of 60 mg. Buspirone may be taken with food or on an empty stomach, but counsel patients to be consistent with whichever approach that is chosen. Healthcare Considerations: Short-Term Symptom Relief: It can take several weeks for the therapeutic effects of SSRIs, SNRIs, and buspirone to take hold. This is a key point to discuss with patients when prescribing these agents. Patients with severe symptoms, or symptoms impacting activities of daily life, may require additional medications for short-term symptom relief and management until the “primary” agent’s effects are felt. Benzodiazepines remain useful medications for short-term or as-needed use in combination with SSRIs and SNRIs. Chlordiazepoxide can also be considered. Clinicians must balance short-term symptom relief with finding the best agent for long-term symptom management. If the patient will receive more than one prescription, educate the patient on why each medication is being prescribed, the difference in how they work, how long each agent takes to work, and how long they can expect to use each medication, among other counseling points. Mirtazapine (Remeron) Mirtazapine is an atypical antidepressant indicated for the treatment of major depressive disorder (MDD). However, the drug has been found useful in treating anxiety disorders and is commonly used off-label to treat GAD, SAD, and PD (Jilani et al., 2021), as well as other conditions including PTSD, obsessive- compulsive disorder (OCD), and insomnia. Mirtazapine increases release of serotonin and norepinephrine by inhibiting central presynaptic alpha-2 receptors. It’s also an antagonist of H1 histamine receptors and serotonin receptors 5-HT2A, 5-HT2C, and 5-HT3 (Jilani et al., 2021). The therapeutic dose range for mirtazapine is 15- 45 mg/day. The recommended starting dose is 15 mg once daily, preferably in the evening or before bedtime due to the drug’s sedating effects (Jilani et al., 2021). Because mirtazapine has a long elimination half-life (20 to 40 hours), clinicians should wait at least one to two weeks before evaluating therapeutic effect and making any dosing adjustments. Mirtazapine clearance is reduced in elderly patients and in patients with moderate or severe hepatic or renal impairment (Jilani et al., 2021). Common adverse effects mirtazapine may cause include drowsiness (54%), dry mouth (25%), weight gain (12%), constipation, and increased cholesterol level. Mirtazapine is known to be sedating, and patients should be counseled on the importance of taking doses just before bedtime. Compared to other antidepressants, mirtazapine is less likely to cause sexual dysfunction (Jilani et al., 2021). Rare but serious adverse drug reactions (ADRs) include thrombocytopenia, neutropenia, and bone marrow suppression. Although rare, cases of life- threatening acute pancreatitis have occurred. Discontinuing mirtazapine can cause withdrawal symptoms (Jilani
Thus, if a patient needs to discontinue mirtazapine, a slow, gradual dose reduction should be used to minimize
discontinuation symptoms. Tricyclic antidepressants
Tricyclic antidepressants (TCAs) are a class of antidepressants which have been used to treat MDD since 1959. These agents are usually not used first-line in current practice, due to propensity for causing a variety of adverse effects on account of their anticholinergic activity. TCAs also have a lower threshold for overdose compared to currently favored agents, including SSRIs (Moraczewski & Aedma, 2021). TCAs have some off-label utility for managing anxiety disorders, although they are not recommended as first-line treatment. TCAs affect five different neurotransmitter pathways (Moraczewski & Aedma, 2021): ● Inhibition of serotonin reuptake in presynaptic terminals. ● Inhibition of norepinephrine reuptake in presynaptic terminals. ● Competitive antagonism of postsynaptic cholinergic alpha-1 and alpha-2 receptors. ● Competitive antagonism of postsynaptic histamine-1 receptors. ● Competitive antagonism of postsynaptic muscarinic receptors. This wide variety of receptor affinity results in TCAs causing a myriad of adverse effects on numerous body and organ systems (Moraczewski & Aedma, 2021). Constipation, dizziness, and dry mouth are the most common class of adverse effects. Other anticholinergic effects are possible, including blurred vision, urinary retention, and confusion. TCAs may cause orthostatic hypotension, weight gain, sedation, and increased appetite, due to effects on alpha-1 and histamine receptors. Combining a TCA with an SSRI is generally not advised, due to the risk for serotonin syndrome. In addition, TCAs can lower the seizure threshold and should be used with caution in patients with epilepsy or taking other medications affecting seizure threshold (Moraczewski & Aedma, 2021). Coronary artery disease (CAD) is not a contraindication for TCA use, but these agents are generally avoided in patients with CAD, due to the risk for cardiac complications. Clinicians must evaluate the patient’s cardiac health before prescribing a TCA. Complications including QTc prolongation, ventricular fibrillation, and sudden cardiac death can occur when TCAs are used in patients with preexisting ischemic cardiac disease (Moraczewski & Aedma, 2021). Due to this risk, TCA use is contraindicated in patients with a family history of sudden cardiac death or QTc prolongation. See Table 4. Table 4: Off-Label TCAs for Treating Anxiety Disorders
FDA Approved Anxiety Disorders
Off-Label Uses GAD, PD, SAD, AG GAD, PD, SAD GAD, PD, SAD GAD, PD, SAD
Therapeutic Dose Range
Medication
Clomipramine (Anafranil) Desipramine (Norpramin) Imipramine (Tofranil) Nortriptyline (Pamelor)
None
100-250 mg/day
None
100-200 mg/day
None
100-300 mg/day
et al., 2021), including: ● Decreased appetite. ● Depression. ● Insomnia.
None
50-150 mg/day
Page 116
Book Code: RPTTX2024
EliteLearning.com/Pharmacy-Technician
Powered by FlippingBook