Excipient capsule formulation

Other excipients that may appear in capsule formulations are disintegrants, and wetting agents. At appropriate concentrations in the... 

We include certain excipients in a formulation specifically because they interact with the physiological fluids and the bodily functions in a certain way. For example, as discussed above, we include disintegrants in immediate release tablet and capsule formulations, because we know that when they encounter the aqueous environment of the stomach, they will cause the tablet or capsule to disintegrate and thereby aid dissolution of the API. Another example is the general case of hydrophilic colloid matrices used as prolonged release drug delivery systems. We know that when these materials contact the aqueous environment of the GIT they swell and create a diffusion barrier that slows the rate of dissolution of the dissolved drug. 

Establish the compatibility of the capsule shell and the capsule contents. Determine the hygroscopic nature of the capsule formulation. For example, a hygroscopic formulation (active ingredient and/or excipients) can pull water from the capsule shell, which could affect the Active ingredient—stability issues such as degradation and morphology changes... 

Certain excipients that are added to formulations to improve filling-machine performance can have an adverse effect on release,because they are hydrophobic in nature. This is true of lubricants, which are added to formulations to prevent adhesion and to improve flow. The most used excipient in capsule formulations in... 

In reality, no single excipient would satisfy all the criteria therefore, a compromise of the different requirements has to be made. For example, although widely used in pharmaceutical tablet and capsule formulations as a diluent, lactose may not be suitable for patients who lack the intestinal enzyme lactase to break down the sugar, thus leading to the gastrointestinal tract symptoms such as cramps and diarrhea. The role of excipients varies substantially depending on the individual dosage form. 

Hashim F, El-Din EZ. Effect of some excipients on the dissolution of phenytoin and acetazolamide from capsule formulations. Acta Pharm Penn 1989 98 197-204. 

The simplest lipid-based formulations contain only one excipient such as Gelucire 44/14, oleic acid, o -tocopherol, corn oil, peanut oil, sesame oil, medium-chain triglyceride, or medium-chain mono- and diglycerides. There are at least 10 commercially available one-lipid excipient oral formulations, and they all happen to be in soft capsules. 

Thus the pharmacist must be careful when choosing the excipients. Pre-formulation studies to identify incompatibilities can be time-consuming but are required to prove that no instability of the active substance will occur during preparation and storage. In the case of the use of licensed products to prepare capsules or powders, it might be difficult to obtain information from the manufacturer. Thus, it is usually safe to dilute crushed tablet with the excipient that is used in the tablet formulation, based on the market authorisation holder who has ensured their compatibility. 

The dose of the drug and its solubility are important considerations in the design of the formulation. The amount and type of active ingredient influences capsule size and the nature and amount of excipients to be used in the formulation. Larger-dose drugs that must be granulated to produce tablets may be more easily direct-filled into hard shell capsules with proper choice of excipients. 

Whether physical mixtures represent real drug-excipient(s) interactions in a capsule or tablet formulation has been debated.57 The use of prototype formulations instead of physical mixtures has been suggested. However, drug substance availability and practicality may limit... 

Pharmaceuticals, for the purpose of this book, means chemical compounds that are used in pharmaceutical production. This can comprise the active ingredient, which is also called active pharmaceutical ingredient (API) or drug substance or drug product and the inert pharmaceutical ingredients (excipients) that are used to formulate a drug product in the form of tablets, capsules, ointments, creams, lotions, parenterals, inhalers, and a variety of drug delivery systems. 

The extent of revalidation required for formulation changes should be determined on a case-by-case basis. Slight adjustments to the formulation may not require further validation work. This would include an adjustment of the excipient ratios, a change in tablet shape, etc. Specificity and accuracy should be re-evaluated for the inclusion of a new excipient into the formulation (e.g., antioxidants, dyes, preservatives). A change in the formulation such as going from a tablet to a capsule or from a liquid to a solid would mean a significant change to the formulation and complete validation should be performed. 

Excipients are sub-divided into various functional classifications, depending on the role that they are intended to play in the resultant formulation, for example, fillers, disintegrants, binders, lubricants and glidants. An added complexity is the fact that certain excipients can have different functional roles in different formulation types. Thus, lactose is widely used as a filler or diluent in solid oral dosage forms, for example, tablets and capsules [2] and as a carrier for inhalation products [3]. 

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