Novel drug delivery systems for herbal antidepressants

Abstract

Depression, a potentially life-threatening mood disorder, affects one in six persons in the United States, or approximately 17.6 million Americans each year. It is one of the top ten causes of morbidity and mortality worldwide as reported by the World Health Organization. Depressed patients are more likely to develop secondary diseases like type 2 diabetes and cardiovascular disease. Furthermore, depression is the third leading cause of global disease burden, accounting for 4.3 % of the total disability-adjusted life years. Predictions based on current exponential rise may assign it to be the leading cause of disease burden by the year 2030. Despite advances in the treatment of depression with selective serotonin reuptake inhibitors (SSRIs) and serotonin and noradrenaline reuptake inhibitors (SNRIs), there continue to be several unmet clinical needs with respect to both the efficacy and the persisting side effects. Herbal drugs with evident antidepressant activity are purported to possess lower risk of precipitating side effects and can be explored as novel drug candidates. Though they find ample space to broaden their therapeutic segment at lab scale, their translation to clinics often has resulted in a failure. The latter is assigned to their compromised bioavailability across the blood-brain barrier (BBB) and attributed to their poor solubility and permeability, photodegradation and lower available systemic concentrations. All these concerns call for the development of novel drug delivery systems (NDDS), which include oral gastro-resistant formulations; transdermal delivery; nasal therapies; nanotechnology-based products, i.e. polymeric and lipidic nanoparticles; self- emulsifying novel drug delivery systems; liposomes; nanostructured lipid carriers; to nanodevices. The commercialisation of the herbal NDDS products especially the nanotech- based delivery system, is governed by stringent regulations, though a few products which fall into the category of modified conventional therapies may get approvals from FDA. This chapter elaborates the need for developing the NDDS for herbal antidepressants (AD). Furthermore, an extensive review of the work done by the researchers around the globe and the constraints are also presented herewith. The regulations governing the approval of product for commercialisation and the future direction for these herbal antidepressants are also discussed.