Delivery of formoterol from a novel multi-dose inhaler Airmax

Promoted Antitumor Activity of Myricetin against Lung Carcinoma Via Nanoencapsulated Phospholipid Complex in Respirable Microparticles

PURPOSE

Myricetin (MYR) flavonoid is well-recognized for its antioxidant, anti-inflammatory and anti-tumor potential. Introducing nanomedicine was the ultimate resort to solve the imperfections of this nutraceutical, namely solubility, stability and delivery issues. The study, thus, aims at developing inhalable microparticles comprising MYR solid lipid nanoparticles (SLNs) for lung cancer therapy.

METHODS

A two-step preparation procedure starting with complexation of MYR with the phospholipid Lipoid-S100, followed by nanoencapsulation in Gelucire-based, surfactant-free SLNs was developed. SLNs were characterized in terms of physicochemical properties, MYR loading, release behavior as well as anti-tumor potential and cellular uptake. Respirable microparticles were then obtained by spray drying SLNs with carbohydrate carriers. Their size, flowability and pulmonary deposition pattern were assessed.

RESULTS

Optimized SLNs were 75.98 nm in diameter with a zeta-potential of -22.5 mV, and an encapsulation efficiency of 84.5%. Attempts to ameliorate drug loading implicate MYR-phospholipid complexation (MYR-PH-CPX) prior to its entrapment in SLNs, which ensured 5-fold increase in drug loading. Viability assays were modified to guarantee MYR chemical stability. Superior antitumor activity of MYR-phospholipid-complex and 3-fold reduction in IC₅₀ were accomplished with MYR-SLNs. This could be related to enhanced cellular uptake revealed by confocal imaging and doubled fluorescence intensity. SLNs entrapping MYR-PH-CPX were spray-dried with carbohydrate carriers to produce respirable microparticles. The latter ensured MMAD of 2.39 μm and span index of 1.84, in addition to good flowability and > 80% release over 8 h. Deposition experiments revealed MMAD of 2.77 μm, FPF of 81.23 and EF of 93% indicating particle deposition in the targeted bronchial region.

CONCLUSIONS

The study highlights the ability of phospholipid-complex on the nanoencapsulation, cellular uptake and antitumor activity of MYR. Formulation of respirable microparticles gives promises of efficacious therapy of lung carcinoma.

How can we bring high drug doses to the lung?

In the last decades, dry powder inhalation has become a very attractive option for pulmonary drug delivery to treat lung diseases like cystic fibroses and lung infections. In contrast to the traditional pulmonary application of drugs for asthma and chronic obstructive pulmonary disease, these therapies require higher lung doses to be administered. The developments and improvements toward high dose powder pulmonary drug delivery are summarized and discussed in this chapter. These include the invention and improvement of novel inhaler devices as well as the further development of formulation principles and new powder engineering methods. The implementation of these strategies is subsequently described for some prototypes and formulations in research and development stage as well as for already marketed dry powder products. Finally, possible adverse effects that can occur after inhalation of high powder doses are shortly addressed.

Advancements in dry powder delivery to the lung

The dry powder inhaler (DPI) has become widely known as a very attractive platform for drug delivery. Many patients have traditionally used DPIs to treat asthma and chronic obstructive pulmonary disease. Recently, the development of new DPIs for delivering therapeutic proteins such as insulin has been accelerated by patient demands, and innovative research. The current market for DPIs has over 20 devices presently in use, and many devices under development for delivering a variety of therapeutic agents. DPIs are recognized as suitable alternatives to pressurized metered dose inhalers for some patients, but the performance of DPI devices may vary according to a given patient's physiological condition. This variation can be associated with the necessary powder dispersion mechanism of each device. As such, much interest has focused on the development of efficient powder dispersion mechanisms, as this effectively minimizes the influence of interpatient variability. This article reviews DPI devices currently available, advantages of newly developed devices, outlines some requirements for future device design.

Bronchodilating effects of cumulative doses of formoterol from a novel multi-dose inhaler (Airmax)

The bronchodilating properties of formoterol from a novel multi-dose inhaler, Airmax 6 microg and from a single-dose dry powder inhaler Foradil Aeroliser 12 microg were investigated in 31 adult asthmatics with FEV1 > or = 60% predicted and a reversibility > or = 12%. Patients received on a single day four doses of formoterol: cumulative dose 6, 12, 24 and 48 microg from Airmax, or 12, 24, 48 and 96 microg from Aeroliser. The mean FEV1 (SD) from baseline to 1 h after the final cumulative dose increased by 0.81 l from 2.62 (0.58) to 3.43 l (0.70) with Airmax and by 0.85 l from 2.65 (0.60) to 3.5 l (0.68) with Aeroliser. All 90% CIs for all four dose comparisons were within the equivalence range +/- 0.11. There was a higher incidence of hypokalaemia and hyperglycaemia at highest doses during treatment with the Aeroliser than with Airmax. In conclusion, formoterol delivered from Airmax provides a dose-dependent bronchodilating effect which is similar to that obtained by Aeroliser, at double the dose.

Airmax: a multi-dose dry powder inhaler

Airmax is a multi-dose dry powder inhaler. An internal pump measures out the drug dose using controlled air pressure. Inhalation transports the drug into a cyclone separator (where active drug is separated from the lactose carrier) and then into the patient airway. In vitro studies indicate that Airmax may be less dependent on airflow than Turbuhaler for drug delivery; greater dose consistency was seen with administration of budesonide via Airmax than via Turbuhaler. At a low flow rate, the lung deposition of budesonide administered via Airmax was greater than that of budesonide administered via Turbuhaler or a pressurised metered dose inhaler in patients with asthma. In cumulative-dose studies, the mean forced expiratory volume in 1 second (FEV(1)) achieved with salbutamol (albuterol) or formoterol administered via Airmax was equivalent to that achieved with twice the dose administered via dry powder inhalers. black triangle In randomised, double-blind studies, budesonide administration via Airmax was equivalent to administration via Turbuhaler with regards to FEV(1) and improvement in asthma symptoms in both adults and children with asthma. The concentration of adenosine monophosphate producing a 20% fall in FEV(1) increased from pretreatment levels by a greater extent with budesonide administered via Airmax, compared with Turbuhaler. Both adults and children preferred Airmax to Turbuhaler, and more found Airmax easier to use. In one study, the majority of children found learning how to use Airmax trade mark easier than learning how to use Turbuhaler.