Chemical Stability of Diphenhydramine in ‘Magic Mouthwash’ Stored at Room and Refrigerated Temperatures for 90-Days

Authors' Affiliations

Kathryn Austin, PharmD Candidate, Gatton College of Pharmacy, East Tennessee State University, Johnson City, TN. Daniel DeArazoza, PharmD, Nicklaus Children’s Hospital, Miami, FL, USA

Location

D.P. Culp Center Ballroom

Start Date

4-5-2024 9:00 AM

End Date

4-5-2024 11:30 AM

Poster Number

115

Name of Project's Faculty Sponsor

Stacy Brown

Faculty Sponsor's Department

Pharmaceutical Sciences

Classification of First Author

Clinical Doctoral Student

Competition Type

Competitive

Type

Poster Presentation

Presentation Category

Health

Abstract or Artist's Statement

Magic Mouthwash (MM) is a mixture of medications prepared by pharmacists in hospitals and community settings daily. It is used to treat mouth sores and oral pain caused by infections and side effects of some medications. MM has a variety of recipes but typically contains equal parts Mylanta, diphenhydramine, and viscous lidocaine. Viscous lidocaine is not preferred for use in magic mouthwash preparations for children due to the risk of systemic side effects if ingested. Mylanta includes simethicone (20mg/5ml) and antacids aluminum hydroxide (200mg/5ml) and magnesium hydroxide (200mg/5ml). The antacids help coat the sores and keep the active ingredients on the mouth and throat longer. Simethicone is used to reduce foaming and gas bubbles within the suspension. Diphenhydramine is an antihistamine that reduces swelling. In this study, we aimed to investigate the chemical stability of diphenhydramine in an MM preparation suited for children. A high-performance liquid chromatography (HPLC) method with ultraviolet (UV) detection was developed for the quantification of diphenhydramine in MM preparations. The chromatographic conditions include an isocratic separation with 10mM triethylammonium acetate (TEAA) in water as the aqueous component and acetonitrile as the organic component. The mobile phase was delivered in a 55%A / 45%B ratio at a flow rate of 0.400 ml/min on an Agilent Eclipse XDB-C18 column (150 x 4.6 mm; 3.5-micron particle size). The column was maintained at 50oC and the UV detector set at 227nm. For the stability investigation, 10 bottles of 60 ml magic mouthwash (1:1 diphenhydramine/Mylanta) were prepared. 5 bottles were kept in the refrigerator and 5 were kept at room temperature. The temperature in each storage condition was recorded on sampling days, and pH of the prepared mouthwashes was measured as a surrogate for the Mylanta stability. The temperature remained stable for both conditions across the sample days. pH remained the same with the most variation occurring on day 90. 5 samples from each condition were evaluated in triplicate for diphenhydramine recovery on days 0, 1, 2, 4, 7, 14, 30, 60, and 90. A fresh calibration curve was prepared daily to facilitate quantification of diphenhydramine in the samples. The 100% assay level was assigned at 1.25 mg/mL, which was the calculated concentration of diphenhydramine in the freshly prepared mouthwash. Percent diphenhydramine recovery was calculated for all samples of each condition with the goal of staying within 90-110% of 1.25mg/ml. The concentration of diphenhydramine in all preparations stayed within the desired 90 – 110% range for the duration of the study. There were no statistically significant differences in the diphenhydramine concentrations between the two conditions or throughout the study sample days. This data supports the preparation of bulk MM using Mylanta + diphenhydramine (1:1 v/v) and storing at room or refrigerated temperature for 90 days (about 3 months).

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Apr 5th, 9:00 AM Apr 5th, 11:30 AM

Chemical Stability of Diphenhydramine in ‘Magic Mouthwash’ Stored at Room and Refrigerated Temperatures for 90-Days

D.P. Culp Center Ballroom

Magic Mouthwash (MM) is a mixture of medications prepared by pharmacists in hospitals and community settings daily. It is used to treat mouth sores and oral pain caused by infections and side effects of some medications. MM has a variety of recipes but typically contains equal parts Mylanta, diphenhydramine, and viscous lidocaine. Viscous lidocaine is not preferred for use in magic mouthwash preparations for children due to the risk of systemic side effects if ingested. Mylanta includes simethicone (20mg/5ml) and antacids aluminum hydroxide (200mg/5ml) and magnesium hydroxide (200mg/5ml). The antacids help coat the sores and keep the active ingredients on the mouth and throat longer. Simethicone is used to reduce foaming and gas bubbles within the suspension. Diphenhydramine is an antihistamine that reduces swelling. In this study, we aimed to investigate the chemical stability of diphenhydramine in an MM preparation suited for children. A high-performance liquid chromatography (HPLC) method with ultraviolet (UV) detection was developed for the quantification of diphenhydramine in MM preparations. The chromatographic conditions include an isocratic separation with 10mM triethylammonium acetate (TEAA) in water as the aqueous component and acetonitrile as the organic component. The mobile phase was delivered in a 55%A / 45%B ratio at a flow rate of 0.400 ml/min on an Agilent Eclipse XDB-C18 column (150 x 4.6 mm; 3.5-micron particle size). The column was maintained at 50oC and the UV detector set at 227nm. For the stability investigation, 10 bottles of 60 ml magic mouthwash (1:1 diphenhydramine/Mylanta) were prepared. 5 bottles were kept in the refrigerator and 5 were kept at room temperature. The temperature in each storage condition was recorded on sampling days, and pH of the prepared mouthwashes was measured as a surrogate for the Mylanta stability. The temperature remained stable for both conditions across the sample days. pH remained the same with the most variation occurring on day 90. 5 samples from each condition were evaluated in triplicate for diphenhydramine recovery on days 0, 1, 2, 4, 7, 14, 30, 60, and 90. A fresh calibration curve was prepared daily to facilitate quantification of diphenhydramine in the samples. The 100% assay level was assigned at 1.25 mg/mL, which was the calculated concentration of diphenhydramine in the freshly prepared mouthwash. Percent diphenhydramine recovery was calculated for all samples of each condition with the goal of staying within 90-110% of 1.25mg/ml. The concentration of diphenhydramine in all preparations stayed within the desired 90 – 110% range for the duration of the study. There were no statistically significant differences in the diphenhydramine concentrations between the two conditions or throughout the study sample days. This data supports the preparation of bulk MM using Mylanta + diphenhydramine (1:1 v/v) and storing at room or refrigerated temperature for 90 days (about 3 months).