**6.1 Passive loading methods**

This loading technique is to load or encapsulate drug molecules before forming or during preparing liposomes [9]. During liposomes preparation when the lipid film dissolved in drug containing aqueous buffer then that hydrophilic or water soluble drugs is loaded at the centre of liposome vesicle. When lipophilic drugs added to lipid phase of liposome components then that lipophilic drug will load in between lipid bilayers. The unentrapped drug is removed using gel-filtration chromatography or dialysis for liposomal dispersion [17]. The drug loading is low for hydrophillic compounds and high for lipophilic compounds in passive loading method. Liposomal vesicles with large size will have superior drug loading than small sized vesicles [18]. Lipid composition always influence for better drug loading by passive loading method [19].

Passive loading includes four types of methods namely,


#### **6.2 Active loading methods**

Certain compounds which have both aqueous and lipid solubility and having ionisable groups can be loaded after formation of vesicles [20]. This type of method is called remote or active loading of drug molecules. In this remote or active loading several methods exist in preparing of liposomes. Doxil™ is one of the liposomal products prepared by this method [21, 22].

#### **6.3 Mechanical dispersion methods**
