Drug substance magnesium stearate

It is important for the formulator of a new drug substance to know with which excipients he can work and with which he cannot. Some pharmaceutical incompatibilities are known to the formulator, e.g., magnesium stearate/aspirin, and glucose/amines [53],... 

A tablet formulation is a complex system that contains the drug substance, usually a hydrophilic Lllersuch as lactose, a disintegrant such as cornstarch, a lubricant such as magnesium stearate, and maybe a Low-regulating excipient such as silicium dioxide (A sliilnfortunately, the quality... 

Fig. 20 DSC curves of 10% drug substance with excipients 1) Original curves 2) curves after 1 month at 50°C/<30% RH and 3) 50°C/75% RH. The initial DSC curves suggest an incompatibility only with mannitol and magnesium stearate. The DSC curves (curves 3) after storage at 50°C/75% RH allow the differentiation of the excipients degradation with stearic acid, calcium sulfate dihydrate, and avicel.

The methods of metal analysis of pharmaceuticals include X-ray fluorescence spectroscopy, AA spectroscopy, and ICP. Most pharmaceutical products are organic substances or biological materials. Active drug molecules rarely contain inorganic or metallic elements, but metallic pharmaceutical compounds such as ferrous sulfate, ferrous gluconate, zinc undecylenate, and magnesium stearate (a commonly used excipient) still exist in the market. 

Finally it should be noted that certain restrictions may have to be incorporated into the packaging material specification, e.g. No lubricants to be used , (magnesium and zinc stearate or similar lubricants may be incompatible with either the drug substance or certain excipients). 

The main details of the formulation and the limits of the experimental domain were given in table 10.8. Other components not noted in the table were the drug substance (1 - 2%) and a lubricant (magnesium stearate). Tablets at 6 mg were made by direct compression of the mixture. The concentration of drug substance (a soluble salt) were allowed to vary between 1% and 2%. Thus, the domain shown in figure 10.7 may be considered as being repeated for each concentration of drug substance tested. 

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