INHALED TCM VIA MDI OR DPI
MDI devices have been used for TCM delivery since the 1960s, and Huashanshen MDI, which contains atropine-type alkaloids of Radix Physochlainae as active ingredients for the treatment of asthma, was recorded in the Chinese Pharmacopoeia 1977. Atropine-type alkaloids are known anticholinergic agents, eliciting antiasthmatic effect like ipratropium. Later, Zhichuanling (containing a combination of clenbuterol and atropine-type alkaloids of Datura stramonium [Yangjinhua]) and Yinhuangpingchuan (containing extracts of ephedra, Semen Ginkgo, Radix Sophorae, and Radix Scutellariae) MDI were also approved by CFDA for the treatment of asthma, whereas SHL CFC MDI was registered for anti-influenza. Apart from these approved MDI products, other TCM formulas, such as Fufang Shuanghua (containing ephedrine analogues), tetrandrine, and Yuchuan (isoproterenol and guaifenesin), have also been formulated as CFC MDI in the literature. However, it should be noted that no evidence may demonstrate the improved efficacy of TCM except SHL in a CFC inhaler compared with the original oral or injectable forms . As for SHL, a clinical trial has revealed that the MDI exhibited comparable effective rates but significantly better results in alleviating coughing and/or lung rales relative to the oral solution or intravenous infusion when used for treating acute respiratory tract infections . With phasing out CFC use in TCM MDI, no progress has yet been made in the development of HFA-based MDI alternatives so far.
In the last decade, DPI devices are proposed to deliver several TCM formulas, including Senecio cannabifolius (Fanhuncao), alkaloids of Radix Physochlainae (Huashanshen), alkaloids of Stephania japonica (Qianjinteng), oligosaccharides of Rehmannia glutinosa (Dihuang), and SHL, but only the latter formula has studied the in vitro aerosol performance of the DPI . In the study, results have shown that SHL might be developed as a DPI product, albeit not HFA MDI due to partial solubility in HFA, and the carrier-based DPI might lead to improved aerosol performance, independent of variation in constituent composition, when spray-dried as corrugated particles .