Pharmacist Rounds: Psychiatry: Clozapine-Induced Sialorrhea
Author: J. Cameron Mitchell, PharmD, BCPS
RP is a 39-year-old man with no known medical history and a psychiatric history notable for chronic paranoid schizophrenia who was recently admitted to your psychiatric unit after 3+ weeks of medication nonadherence. Over the next few weeks clozapine was restarted at 25 mg QHS for his psychosis and titrated to 100 mg PO BID. RP has now begun to complain of drooling that is evidenced by soaking of his pillow and bed linens overnight and difficulty speaking. What pharmacologic options should be considered to help combat RP’s excessive drooling?
Clozapine is a highly effective second-generation antipsychotic (SGA), usually reserved for patients refractory to other antipsychotics.1 Apart from some of clozapine’s better known and potentially fatal adverse effects (ie, seizure, myocarditis, and agranulocytosis), it is also associated with other more common side effects related to its binding at muscarinic and a-adrenergic receptors.2 Sialorrhea, or excessive drooling, is one of clozapine’s most common adverse effects, occurring in as many as 30% to 80% of patients.3 Clozapine-induced Sialorrhea (CIS) is not generally thought to be dose-related and can occur anytime throughout the day.2-4 Complications from CIS can range from the uncomfortable (ie, social awkwardness and speech difficulties) to the potentially life-threatining (ie, parotiditis, choking, and aspiration).2-4 The 2 leading theories behind the mechanism of CIS are 1) potent agonism at muscarinic M4 receptors and 2) blockade of a-2 adrenergic receptors, which both lead to an increase in salivary flow.2-6
Although several pharmacotherapeutic strategies for the treatment of CIS have been employed, little exists in the way of convincing clinical evidence to help guide drug selection.3 Historical treatments in the US have included systemic antimuscarinic drugs (ie, benztropine, glycopyrrolate, trihexyphenidyl, and amitriptyline) and a-adrenergic agents (clonidine, guanfacine, and terazosin); however, these drugs are often associated with systemic side effects that can decrease tolerabilty and treatment adherence.4 Two popular treatments given their ease of administration, tolerability, and low-risk of systemic side effects are the non-selective, muscarinic receptor antagonists atropine sulfate and ipratropium bromide administered sublingually.2,3,6-12 Atropine is usually administered as 1 to 2 drops of the 1% ophthalmic solution sublingually 2 to 3 times daily.* Ipratropium bromide is usually administered as 1 to 2 sprays of the 0.03% nasal spray formulation sublingually at bedtime, and then increased to 2 to 3 times daily as needed.3
In our case, RP was initially treated with 2 sprays of ipratropium bromide 0.03% nasal spray sublingually at bedtime for 3 days, which was subsequently increased to 3 times daily as needed for drooling. Over the next 2 weeks RP experienced an almost complete cessation of nighttime drooling, but also endorsed several episodes of dry mouth directly following ipratropium bromide administration. These episodes became very bothersome, warranting discontinuation of ipratropium bromide. Atropine sulfate 1% ophthalmic solution was then initiated at 2 drops sublingually every 6 hours as needed for drooling (swish and spit). The atropine regimen resulted in similar efficacy and was better tolerated, resulting in only a few mild episodes of dry mouth throughout the next several weeks.
*Swishing after sublingual atropine administration is thought to increase efficacy by maximizing contact with the oral mucosa.
J. Cameron Mitchell, PharmD, BCPS, is a clinical pharmacist at Central Regional Hospital in Butner, North Carolina.
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