Immediate release dosage forms

Reppas, C., Shah, V. P. Dissolution testing as a prognostic tool for oral drug absorption immediate release dosage forms. Pharm. Res. 1998, 15, 11-22. 

All of the products considered in detail were immediate-release dosage forms. 

Therefore, for a nondegradable drug dosed in immediate release dosage forms, the absorption and transit in the gastrointestinal tract can be depicted as follows. Stomach ... 

A direct in vivo assessment was carried out with the single-pass perfusion approach in the human jejunum by using the Loc-I-Gut technique with R/S-verapamil (log D6 5 2.7, octanol/water pH 7.4 MW 455 Da) as the model compound for CYP 3A4 and P-gp-mediated local intestinal kinetics [2, 34, 35, 122] (see Figs. 7.7 and 7.9). The Peff for both enantiomers at each of the concentrations (4.0, 40, 120, and 400 mg L-1) was 2.5 x 10 4, 4.7 x 105.5 x 104 and 6.7 x 104 cm s-1, respectively (Fig. 7.15) [34, 35], A luminal concentration of 400 mg L 1 is expected to be achieved in the upper part of the small intestine after oral administration of a 100-mg dose of verapamil in an immediate-release dosage form [1, 34, 35], The three other perfusate concentrations represent fractions of the dose when 30%, 10%, and 1%, respectively are left to be absorbed [34, 35], The increased in vivo jejunal Peff of R/S-vcrapamil, along with its increased luminal perfusate concentration, is in accordance with a saturable efflux mechanism mediated by... 

Model-independent techniques compare data pairs observed at corresponding time values, where time is only a class effect, as in a paired -test or in an ANOVA. A data-poor set of only two or three observations, originating from routine quality control of an immediate-release dosage form, cannot be treated other than model independent. 

In 1995, the FDA issued Scale-up and Post-Approval Changes (SUPAC) guidance for the industry (128) for immediate release dosage forms and in 1997, SUP AC MR guidance was released for modified release dosage forms (129). 

Note MR, Modified-release dosage form ER, extended-release dosage form DR, delayed-release dosage form IR, immediate-release dosage form. ... 

Extended Release Extended release products are formulated to make the drug available over an extended period after ingestion. This allows a reduction in dosing frequency compared to a drug presented as a conventional dosage form (e.g., as a solution or an immediate release dosage form). 

Modified Release Dosage Forms Dosage forms whose drug-release characteristics of time course and/or location are chosen to accomplish therapeutic or convenience objectives not offered by conventional dosage forms such as a solution or an immediate release dosage form. Modified release solid oral dosage forms include both delayed and extended release drug products. 

The function Cs represents the concentration tune course that would result from the instantaneous absorption of a unit amount of drug and can be estimated from either i.v. bolus data, oral solution, suspension or rapidly releasing (in vivo) immediate release dosage forms. 

McGilveray, I. J. 1996. Overview of workshop In vitro dissolution of immediate release dosage forms Development of i n vivo relevance and quality control issfibsg I nformation Journal30 1029-1037. 

There have been a number of formulation approaches explored and widely practiced in the pharmaceutical industry to improve delivery of poorly water-soluble compounds especially in development of immediate release dosage forms. These delivery approaches are based on various techniques described as following ... 

Klein S. 2006. The minipaddle apparatus - a useful tool in the early development stage Experiences with immediate-release dosage forms. Dissol. Technol. 13(4) 6-11. 

Because P-gp expression was reported to increase from the proximal to the distal regions of the small intestine (Yumoto et al. 1999), Lacombe et al. suggested gastroretentive or immediate release dosage forms for the delivery of P-gp substrates (Lacombe et al. 2004). It has been shown, for example, in everted gut sacs of rats that the transport of digoxin is about 2.5-fold higher in the proximal jejunum in comparison to the terminal ileum. 

Comparative pharmacokinetic profiles of nifedipine delivered from Procardia XL, an osmotic pressure-controlled drug delivery system, once-a-day versus that from Procardia, an immediate-release dosage form, taken on time 0, 8 and 16 in human volunteers. Modified from Y.W. Chien. Oral drug delivery and delivery systems. Y.W.Chien (ed.) (1992) Novel Drug Delivery Systems. Marcel Dekker, Inc. New York, pp. 139-196... 

Assay (dissolution) +30% of specified range (for immediate release dosage form). If the specification for a controlled release product (modified release or sustained release) covers a region from 20% (after 1 hr) to 90% (after 24 hr), the validated range would cover 50% of 1-hr limit (20% x 50% = 10%) to 130% of the label claim (label claim x 1.3). 

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