Immediate-release, drugs

When immediate-release products are used, die nurse administers die drug every 6 hours, hi some adults, intervals of 8 hours between dosing may be satisfactory. 

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. 

ER, extended-release FDA, Food and Drug Administration HDL, high-density lipoprotein IR, immediate-release LDL, low-density lipoprotein SR, sustained-release. 

Bupropion causes insomnia, nightmares, decreased appetite, anxiety, and tremors, but the most concerning adverse effect is seizures. Because of the risk for seizures, patients who should not receive the drug include those with a CNS lesion or those with a history of seizures, head trauma, or bulimia. The daily dose of bupropion should not exceed 450 mg/day, and any single dose of the immediate-release formulation should not exceed 150 mg/day Occurrences of insomnia and/or nightmares often respond to moving the last daily dose from bedtime to late afternoon.7,9,22,23... 

A system was developed at Roche Laboratories whereby a sheet (or web ) was coated with a drug/binder mixture. The solid dosage units were then punched from the web [168]. This system was very flexible and amenable to immediate release and sustained-release technologies. However, due to the im-practicality of the system, it was abandonned in the mid-1980s and is only of historical significance. 

Often these design criteria involve competitive requirements. What is best for meeting one criterion may be counterproductive in meeting another. For example, certain excipients such as the hydrophobic stearate lubricants are important for efficient manufacture, yet they have the potential to retard the release of drug from an immediate-release formulation. The design of a dosage form thus frequently requires the optimization of formulation and process variables in a way that best meets all design criteria. 

Waiver of in vivo bioavailability and bioequivalence studies for immediate release solid oral dosage forms based on a biopharmaceutics classification system. Center for Drug Evaluation and Research, Food and Drug Administration, issued 8/2000, posted 8/31/2000. http //www.fda.gov/cder/guidance/ index, htm... 

P. Sathe, J. Venitz, and L. Lesko, Evaluation of truncated areas in the assessment of bioequivalence of immediate release formulations of drugs with long half lives and CMax with different dissolution rates, Pharm. Res, 16, 939 (1999). 

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 ... 

Zentner and coworkers [24,26] utilized this information in their development of a system that releases this drug over a 24 hr period. The use of NaCl to modulate the release of diltiazem presents an interesting problem in that the concentration of the solubility modifier must be maintained within certain limits and below its saturation solubility within the device. To solve this problem, core formulations were developed that contained both free and encapsulated NaCl. The encapsulated NaCl was prepared by placing a microporous coating of cellulose acetate butyrate containing 20 wt% sorbitol onto sieved NaCl crystals. The coated granules released NaCl over 12-14 hr period via an osmotic mechanism into either water or the core tablet formulation. The in vitro release profile for tablets (core I devices) containing 360 mg of diltiazem HC1 and 100 mg of NaCl equally divided between the immediate release and controlled release fractions... 

CDER Waiver of in vivo bioavailability and bioequivalence studies for immediate-release solid oral dosage forms based on a biopharmaceutics classification system Food and Drug Administration, 2000. 

CDER Guidance for Industry. SUPAC-IR Immediate-Release Solid Oral Dosage Forms Scale-Up and Post-Approval Changes Chemistry, Manufacturing and Controls, In Vitro Dissolution Testing, and In Vivo Bioequivalence Documentation US Food and Drug Administration, 1995. 

Fast-dissolving formulations (flash-dispersing) are not primarily intended to be for buccal delivery the issue here is that they may be taken without water. This causes an important difference in performance relative to ordinary immediate-release products, especially if the drug is in suspension. If the material is swallowed dry, it may adhere to the fundus area, where the amount of shear is low. This causes a significant fraction of the material to be retained resulting in tailing of the absorption phase and an apparently decreased AUC as the material is released over several hours. 

Oxybutynin immediate-release (IR) has been the drug of first choice for UUI and the gold standard against which other drugs are compared. Financial considerations favor generic oxybutynin IR. 

Dissolution indicates the rate-limiting step for compound absorption when drugs are administered orally. The solubility of a pharmaceutical compound represents its maximum concentration in an aqueous buffer. Additional compound will not dissolve above this concentration. The solubility value is often heavily dependent upon pH and temperature and is typically measured at physiologically important pH levels and body temperature. The standards for dissolution testing are determined by the United States Pharmacopoeia (USP). Testing typically requires sampling of a solution at 15, 30, 45, and 60 min for immediate-release products. /./Pl.C is ideally suited for use in conjunction with USP apparatus types I or II and can rapidly analyze multiple time points or replicate samples. 

U.S. Department of Health and Human Services Food and Drug Administration Center for Drug Evaluation and Research (CDER). Guidance for Industry Waiver of In Vivo Bioavailability and Bioequivalence Studies for Immediate Release Solid Oral Dosage Forms Based on a Biopharmaceutics Classification System. 2000. 

---