a Many of the liquids are volatile substances and as such must be physically sealed from the atmosphere to prevent their loss a Another problem associated with liquid drugs is that those intended for oral administration cannot generally be formulated into tablet form Formulation and stability difficulties arise less frequently with solid dosage forms than with liquid pharmaceutical preparations
◼ Many of the liquids are volatile substances and as such must be physically sealed from the atmosphere to prevent their loss. ◼ Another problem associated with liquid drugs is that those intended for oral administration cannot generally be formulated into tablet form. ◼ Formulation and stability difficulties arise less frequently with solid dosage forms than with liquid pharmaceutical preparations
2)Microscopic examination a Microscopic examination of the raw drug substance is an important step in preformulation work. a It gives an indication of particle size and particle size range of the raw material as well as the crystal structure
2) Microscopic examination ◼ Microscopic examination of the raw drug substance is an important step in preformulation work. ◼ It gives an indication of particle size and particle size range of the raw material as well as the crystal structure
3)Melting point depression A characteristic of a pure substance is a defined melting point or melting range. If not pure, the substance will exhibit a depressed melting point. This phenomenon is commonly used to determine the purity of a drug substances before inclusion in the same dosage form
3) Melting point depression ◼ A characteristic of a pure substance is a defined melting point or melting range. If not pure, the substance will exhibit a depressed melting point. ◼ This phenomenon is commonly used to determine the purity of a drug substances before inclusion in the same dosage form
a The melting point, or freezing point, of a pure crystalline solid is defined as that temperature where the pure liquid and solid exist in equilibrium 纯净的结晶性固体的熔点或冰点系指纯液 体和固体达到平衡时的温度。) The melting point/range of a drug can be used as an indicator of purity of chemical substances (a pure substance would ordinarily be characterized by a very sharp melting peak)
◼ The melting point, or freezing point, of a pure crystalline solid is defined as that temperature where the pure liquid and solid exist in equilibrium. （纯净的结晶性固体的熔点或冰点系指纯液 体和固体达到平衡时的温度。） ◼ The melting point/range of a drug can be used as an indicator of purity of chemical substances (a pure substance would ordinarily be characterized by a very sharp melting peak)
a An altered peak or a peak at a different temperature may be indicative of an adulterated or impure arug. (峰形的改变或熔点峰温度的差异表示药物 混杂其他物质或不纯)
◼ An altered peak or a peak at a different temperature may be indicative of an adulterated or impure drug. （峰形的改变或熔点峰温度的差异表示药物 混杂其他物质或不纯）