Pulmonary peptide delivery: effect of taste-masking excipients on leuprolide suspension metered-dose inhalers

Estimating inhalation bioavailability for peptides and proteins 1 to 10 kDa in size

Inhalation is a critical route for occupational exposure. To protect workers from adverse effects, health-based exposure limits (HBELs) are derived using chemical-specific information including inhalation bioavailability. Inhalation bioavailability of large proteins is well studied and generally accepted to be 1% or less. However, the inhalation bioavailability of peptides and proteins 1-10 kDa in size is not well defined. The goal of this study was to expand upon previous analyses and evaluate the inhalation bioavailability of small peptides. Inhalation bioavailability data for 72 peptides and protein samples ranging from 1.1 to 10.9 kDa in size were evaluated. The median inhalation bioavailability was 20%, which is in agreement with previously published analyses. Inhalation bioavailabilities for the vast majority were below 50%. Interestingly, species, peptide size, and peptide identity did not correlate with inhalation bioavailability. Other factors including inhalation dosimetry, peptide degradation, and chemical characteristics also decrease the amount of peptide available for absorption. Together, the median bioavailability of 20% is likely an appropriate estimate of systemic exposure and is sufficiently protective in most cases for the purposes of occupational exposure safety. Thus, in the absence of peptide-specific data or concerns, an inhalation bioavailability default of 20% is recommended for 1-10 kDa peptide and proteins.

Manufacturing and device options for the delivery of biotherapeutics

Biotherapeutic aerosol formulations are an intense area of interest for systemic and local drug delivery. This article provides a short overview of typical factors required specifically for biotherapeutic aerosol formulation design, the processing options open for consideration, and the issue of inhalation device selection. Focusing on spray drying, four case studies are used to highlight the relevant issues, describing investigations into: (1) the mechanical stresses occurring in bacteriophage formulations during spray-dryer atomization; (2) modeling of the spray-dryer process and droplet drying kinetics, to assist process design and predictions of formulation stability; (3) a predictive approach to the design and processing of a five-component dry powder aerosol formulation; and (4) the survival of bacteriophages after pressurized metered dose inhaler atomization.

Mechanisms of absorption and elimination of drugs administered by inhalation. Ther Deliv. 2013;4:1027-1045. [PMID: 23919477 DOI: 10.4155/tde.13.67]

Pulmonary drug delivery is an effective route for local or systemic drug administration. However, compared with other routes of administration, there is a scarcity of information on how drugs are absorbed from the lung. The different cell composition lining the airways and alveoli makes this task extremely complicated. Lung cell lines and primary culture cells are useful in studying the absorption mechanisms. However, it is imperative that these cell cultures express essential features required to study these mechanisms such as intact tight junctions and transporters. In vivo, the drug has to face defensive physical and immunological barriers such as mucociliary clearance and alveolar macrophages. Knowledge of the physicochemical properties of the drug and aerosol formulation is required. All of these factors interact together leading to either successful drug deposition followed by absorption or drug elimination. These aspects concerning drug transport in the lung are addressed in this review.

Modulite technology in the development of formoterol HFA pMDI: clinical evidence and future opportunities

This article is based on published safety and efficacy data on formoterol pressurized metered-dose inhalers (pMDIs) developed with the Modulite technology. This technology allows the development of ozone-friendly inhaled drugs that replace the same doses of chlorofluorocarbon (CFC)-formulated products and enables the attainment of new formulations with extra-fine particles and improved lung deposition. Clinical pharmacology, as well as clinical studies against comparators, have demonstrated that formoterol Modulite and the existing dry powder inhaler and CFC formoterol formulations have a similar pharmacokinetic profile, are clinically equivalent in bronchodilating effects and exhibit a similar potential for systemic side effects. Therefore, the Modulite formoterol hydrofluoroalkane-based formulation in extra-fine particles is a valuable therapeutic option for both patients and physicians in the management of asthma and chronic obstructive pulmonary disease.

Utilization of a Modified Special‐Cubic Design and an Electronic Tongue for Bitterness Masking Formulation Optimization

A unique modification of simplex design was applied to an electronic tongue (E-Tongue) analysis in bitterness masking formulation optimization. Three formulation variables were evaluated in the simplex design, i.e. concentrations of two taste masking polymers, Amberlite and Carbopol, and pH of the granulating fluid. Response of the design was a bitterness distance measured using an E-Tongue by applying a principle component analysis, which represents taste masking efficiency of the formulation. The smaller the distance, the better the bitterness masking effect. Contour plots and polynomial equations of the bitterness distance response were generated as a function of formulation composition and pH. It was found that interactions between polymer and pH reduced the bitterness of the formulation, attributed to pH-dependent ionization and complexation properties of the ionic polymers, thus keeping the drug out of solution and unavailable to bitterness perception. At pH 4.9 and an Amberlite/Carbopol ratio of 1.4:1 (w/w), the optimal taste masking formulation was achieved and in agreement with human gustatory sensation study results. Therefore, adopting a modified simplex experimental design on response measured using an E-Tongue provided an efficient approach to taste masking formulation optimization using ionic binding polymers.

Propellant-driven metered-dose inhalers for pulmonary drug delivery

The current market for pulmonary drug delivery is at a bottleneck. The therapeutic advantages of inhalation aerosols, and the potential for the lungs as a route for systemically acting drugs, vaccines and gene therapeutic agents, have resulted in a rapid growth of the industry. Alongside this, the environment of inhaler design and formulation has changed markedly in recent years. Environmental concerns over propellants, the commercial success of dry powder inhalers, and the apparent lack of advancement of propellant-driven metered-dose inhalers (pMDIs) has led to a less clear future for these devices. This review critically assesses these pressures and also potential opportunities for the pMDI. It is proposed that the future role of pMDIs will be determined by several important forces that can be classified under 'technology development' or 'market climate' categories. Technology development forces will be strengthened by the ability of the industry to have a systematic understanding of mechanisms of spray formation, perform subsequent and continued device and formulation advances, and a focus on all patient groups: particularly paediatric and geriatric populations. The ability to succeed in these areas will be largely determined by the willingness to invest in fundamental research of pMDI technologies.

Optimized dose delivery of the peptide cyclosporine using hydrofluoroalkane-based metered dose inhalers

The goal of this study was to illustrate the potential to deliver relatively high doses of a therapeutic peptide using hydrofluoroalkane (HFA) metered dose inhaler (MDI) drug delivery systems. For the purposes of this study, cyclosporine was used as the model compound. Cyclosporine formulations, varying in peptide concentration, ethanol cosolvent concentration, and propellant type, were evaluated and optimized for product performance. As ethanol concentration was decreased from 10 to 3% by weight, fine particle fraction (the mass of cyclosporine which passes through a 4.7-micron cut point divided by the total mass of cyclosporine delivered ex-valve) increased from 34 to 68% for 227 and 33 to 52% for 134a formulations. Because of the excellent solubility properties of cyclosporine in HFA-based systems, minimal or no ethanol was needed as a cosolvent to achieve cyclosporine concentrations of 1.5% w/w. With these formulations, it was possible to obtain a fine particle mass (mass of particles <4.7 microns) greater than 500 microg per actuation. In addition, one formulation was chosen for stability analysis: 0.09% w/w cyclosporine, 10% w/w ethanol, 134a. Three different types of container closure systems (stainless steel, aluminum, and epoxy-coated canisters) and two storage configurations (upright and inverted) were evaluated. Cyclosporine was determined to be stable in HFA 134a-based MDI systems, regardless of container closure system and configuration, over a 2-year period. Cyclosporine represents a compelling example of how significant peptide doses are attainable through the use of solution-based MDIs. It has been shown that through formulation optimization, 2-3 mg of the peptide, cyclosporine, may be delivered in five actuations to the lung for local or systemic therapy.

Taste masking technologies in oral pharmaceuticals: recent developments and approaches

Taste is one of the most important parameters governing patient compliance. Undesirable taste is one of several important formulation problems that are encountered with certain drugs. Oral administration of bitter drugs with an acceptable degree of palatability is a key issue for health care providers, especially for pediatric patients. Several oral pharmaceuticals, numerous food and beverage products, and bulking agents have unpleasant, bitter-tasting components. So, any pharmaceutical formulation with a pleasing taste would definitely be preferred over a competitor's product and would translate into better compliance and therapeutic value for the patient and more business and profits for the company. The desire of improved palatability in these products has prompted the development of numerous formulations with improved performance and acceptability. This article reviews the earlier applications and methodologies of taste masking and discusses the most recent developments and approaches of bitterness reduction and inhibition for oral pharmaceuticals.