انت هنا الان : شبكة جامعة بابل > موقع الكلية > نظام التعليم الالكتروني > مشاهدة المحاضرة
الكلية كلية الصيدلة
القسم فرع الصيدلانيات
المرحلة 2
أستاذ المادة ظافر قحطان سعيد الامين الماشطة
5/28/2011 1:16:23 PM
Polymer complexes
Polyethylene glycols, polystyrene, carboxymethyl cellulose, and similar polymers containing nucleophilic oxygens can form complexes with various drugs. The incompatibilities of certain polyethers, such as the Carbowaxes, and Tweens with tannic acid, salicylic acid, and phenol, can be at¬tributed to these interactions. Some of these interactions may occur in suspensions, emulsions, oint¬ments, and suppositories leading to incompatibility which may be man¬ifested as a precipitate, flocculate, delayed biologic absorption, loss of preservative action, or other undesirable physical chemical, and pharmacologic effects.
Crosspovidone, is a disintegrant in pharmaceutic granules and tablets. It does not interfere with gastrointestinal absorption because the binding to drugs is reversible. It is able to bind drugs like acetaminophen, caffeine and papaverine hydrochloride owing to its dipolar character and porous structure.
Solutes in parenteral formulations may migrate from the solution and interact with the wall of a polymeric container. The ability of a polyolefin con¬tainer to interact with drugs depends linearly on the octanol-water partition coefficient of the drug. Polymer-drug container interactions may result in loss of the active component in liquid dosage forms.
Inclusion compounds
The class of addition compounds known as inclusion or oc¬clusion compounds results more from the architecture of molecules than from their chemical affinity. One of the con¬stituents of the complex is trapped in the open lattice or cage-like crystal structure of the other to yield a stable arrangement.
Channel lattice type
The choleic acids (bile acids) can form a group of complexes principally involving deoxycholic acid in combination with paraffins, organic acids, esters, ketones, and aromatic com¬pounds and with solvents such as ether, alcohol, and dioxane. The crystals of deoxycholic acid are arranged to form a channel into which the complexing molecule can fit.
Layer type
Some compounds, such as the clay of bentonite can trap hydrocarbons, alcohols, and glycols between the layers of their lattice. Graphite can also intercalate compounds between its layers.
Clathrates
The clathrates crystallize in the form of a cagelike lattice in which the coordinating compound is entrapped. Chemical bonds are not involved in these complexes, and only the molecular size of the encaged component is of importance. The stability of a clathrate and the confinement of a prisoner was observed, and this stability is due to the strength of the structure, that is, to the high energy that must be expended to decompose compound. The highly toxic agent hydroquinone (quinol) crystallizes in a cagelike hydrogen-bounded structure, forming a holes of 4.2إ and permit the entrapment of one small molecule to about every two quinol molecules. Small molecules such as methyl alcohol, CO2, and HCl may be trapped in these cages, but smaller molecules such as H2 and larger molecules such as ethanol cannot be trapped. One official drug, warfarin sodium USP, is clathrate of water, isopropyl alcohol, and sodium warfarin in the form of white crystalline powder.
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
|