Intranasal Drug Delivery: A Promising Route for Therapeutics

Abstract

Introduction

Intranasal drug delivery has gained increasing attention as an alternative to conventional administration routes such as oral or injectable methods. The nasal cavity offers a unique combination of advantages: a large surface area for absorption, high vascularization, and the ability to bypass first-pass hepatic metabolism. These characteristics enable rapid onset of action and improved bioavailability for many drugs [1]. Traditionally employed for local therapies in allergic rhinitis or sinusitis, intranasal delivery is now being explored for systemic treatment of pain, hormonal disorders, neurological diseases, and even vaccination. Its non-invasive, needle-free nature also enhances patient compliance, making it a versatile and attractive option in modern drug delivery [2].

Discussion

The success of intranasal delivery relies on the physiological and anatomical properties of the nasal cavity. Drugs administered intranasally are absorbed through two main pathways: the respiratory epithelium, which facilitates systemic absorption, and the olfactory region, which offers direct access to the central nervous system (CNS). This latter route makes intranasal delivery particularly valuable for targeting brain-related conditions, bypassing the restrictive blood-brain barrier [3].

Intranasal formulations have already demonstrated success in several therapeutic areas. Nasal sprays of corticosteroids are widely used for managing allergic rhinitis, while intranasal calcitonin and desmopressin are effective in treating osteoporosis and diabetes insipidus, respectively. More recently, intranasal fentanyl has been employed for rapid pain relief, especially in palliative care and emergency medicine, where fast onset is critical [4].

One of the most promising applications is in neurological and psychiatric disorders. Intranasal delivery enables direct transport of drugs to the brain via the olfactory and trigeminal nerves. This route is being studied for therapies against Alzheimer’s disease, Parkinson’s disease, epilepsy, and depression. For instance, intranasal administration of insulin and neuropeptides has shown potential in improving cognitive function without causing systemic side effects [5].

In addition, intranasal vaccines are under development, aiming to elicit both systemic and mucosal immune responses. Such vaccines provide the dual benefit of needle-free administration and enhanced protection at the entry site of respiratory pathogens. The success of intranasal influenza vaccines has further validated this approach.

Despite its potential, intranasal delivery faces challenges. The nasal cavity has a limited dosing volume (typically less than 200 microliters per nostril), which restricts the amount of drug that can be delivered. Mucociliary clearance also rapidly removes substances from the nasal surface, reducing residence time and drug absorption.

Conclusion

Intranasal drug delivery represents a versatile and patient-friendly approach with applications extending beyond local therapy to systemic and CNS-targeted treatments. Its advantages of rapid absorption, avoidance of first-pass metabolism, and non-invasiveness make it a strong candidate for addressing unmet medical needs. With innovations in formulation and device design, intranasal delivery is poised to play an increasingly important role in treating neurological disorders, managing pain, and developing next-generation vaccines. While challenges of limited dosing capacity and mucociliary clearance persist, continued research and technological advances promise to unlock its full therapeutic potential, offering a future of safer, faster, and more effective treatments [6].

References

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