Recent advances in drug delivery to the central nervous system by inhalation

ABSTRACT

Introduction

Drugs need to enter the systemic circulation efficiently before they can cross the blood–brain barrier and reach the central nervous system. Although the respiratory tract is not a common route of administration for delivering drugs to the central nervous system, it has attracted increasing interest in recent years for this purpose.

Areas covered

In this article, we compare pulmonary delivery to three other common routes (parenteral, oral, and intranasal) for delivering drugs to the central nervous system. Recent studies delivering drugs for different neurological disorders via inhalation are then discussed to illustrate the strengths of pulmonary delivery.

Expert opinion

Recent studies provide strong evidence and rationale to support inhaling neurological drugs. Since inhalation can achieve improved pharmacokinetics and rapid onset of action for multiple drugs, it is a noninvasive and efficient method to deliver drugs to the central nervous system. Future research should focus on delivering other small and macro-molecules via the lungs for different neurological conditions.

KEYWORDS:

• Central nervous system
• inhalation
• inhalers
• neurological disorders
• pulmonary delivery

Abbreviations

Table

Article highlights

• Common routes of drug administration to the central nervous system include parenteral, oral, and intranasal delivery. Although they have some advantages, they have limited applicability in various situations so a better alternative is needed.

• Pulmonary delivery of drugs to the central nervous system is not new but mainly limited to anesthesia or analgesia. Delivering other neurological drugs via the lungs has attracted much interest in recent years.

• The benefits of delivering neurological drugs to the central nervous system via inhalation include less erratic absorption, increased bioavailability, rapid onset of action, reduced adverse effects, and improved convenience and tolerance.

• More existing and investigational neurological drugs are expected to be administered via inhalation in the future.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded. f