Intranasal Delivery: Formulation Factors and Insights Into User Experience

Improving nasal spray use experience is typically not addressed as a key product requirement even though sensations of bitterness, sourness, astringency, or burning after intranasal application can cause significant repulsion, consumer non-compliance from recommended usage and product rejection. Extensive studies have been carried out by academia and industry alike into the formulation characteristics of sprays and consumer preferences to make nasal sprays more "acceptable" by patients. Due to lack of a collative synopsis of these works, this review article attempts to gather and summarize these studies, address the various attributes that impact post spray experience, and provide suggestions towards maximizing user compliance. We systematically categorized a range of factors which can contribute to unpleasant experiences using nasal sprays including anatomical characteristics of the nose, formulation and device properties, formulation components and dosages, etc. Furthermore, we collated relevant information from pharmaceutical and non-pharmaceutical domains to create a comprehensive knowledge base to frame the scope of the issue. Unpleasant sensorial attributes can be controlled by designing the formulation with a thorough understanding of product-device interactions and novel use of excipients. By choosing excipients such as taste masking agents, flavors, and novel polymers the behavior of the product in the nasal canal can be modulated to block the burning, astringent or bitterness sensation on spray use. This paper discusses these factors in comprehensive detail while offering solutions to ensure a superior product experience. The paper also discusses challenges to adoption and compliance strategies of some newer techniques and excipients.