●●●●● ●●●● 4)Water-soluble bases ●●0 ●●● ●●●● Water-soluble bases do not contain oleaginous components They are completely water-washable and often referred to as‘ greaseless(无脂物 Because they soften greatly with the addition of water, large amounts of aqueous solutions are not effectively incorporated into these bases They mostly are used for the incorporation of solid substances
4) Water-soluble bases Water-soluble bases do not contain oleaginous components. They are completely water-washable and often referred to as ‘greaseless’（无脂物）. Because they soften greatly with the addition of water, large amounts of aqueous solutions are not effectively incorporated into these bases. They mostly are used for the incorporation of solid substances
Polyethylene glycol ointment ●●●●● ●●●● ●●0 ●●● ●●●● Polyethylene glycol (PEG)is a polymer of ethylene oxide and water represented by the formula: H(OCH2CH2),OH in which n represents the average number of oxyethylene groups PEGs having average molecular weights below 600 are clear, colorless liquids, those with molecular weights above 1000 are wax like white materials those with molecular weights in between are semisolids
Polyethylene glycol ointment Polyethylene glycol (PEG) is a polymer of ethylene oxide and water represented by the formula: H(OCH2CH2 )nOH in which n represents the average number of oxyethylene groups. PEGs having average molecular weights below 600 are clear, colorless liquids; those with molecular weights above 1000 are waxlike white materials; those with molecular weights in between are semisolids
●●●●● Selection of the appropriate base .999 ●●● ●●●● Desired release rate of the drug substance from the ointment base: Desirability for topical or percutaneous drug absorption Desirability of occasion of moisture from the skin;
Selection of the appropriate base Desired release rate of the drug substance from the ointment base; Desirability for topical or percutaneous drug absorption; Desirability of occusion of moisture from the skin;
●●●●● ●●●● ●●0 ●●● ●●●● Stability of the drug in the ointment base; Effect of the drug on the consistency or other features of the ointment base The desire for a base that is easily removed by washing with water
Stability of the drug in the ointment base; Effect of the drug on the consistency or other features of the ointment base The desire for a base that is easily removed by washing with water
●●●●● ●●●● Preparation of ointments ●●0 ●●● ●●●● Ointments are prepared by two general methods Incorporation(加入法) Fusion(融合法 The method used depends primarily on the nature of the ingredients
Preparation of ointments Ointments are prepared by two general methods: - Incorporation （加入法） - Fusion（融合法） The method used depends primarily on the nature of the ingredients