Drugs delayed-release

These dosage forms include tablets, capsules, solutions, suspensions, conventional/immediate release, and modified (extended, delayed) release drug products. 

As defined in the USP, delayed-release drug products are dosage forms that release the drugs at a time later than immediately after administration (i.e., these drug products exhibit a lag time in quantifiable plasma concentrations). 

Typically, coatings (e.g., enteric coatings) are intended to delay the release of medication until the dosage form has passed through the acidic medium of the stomach. In vivo tests for delayed-release drug products are similar to those for extended-release drug products. In vitro dissolution tests for these products should document that they are stable under acidic conditions and that they release the drug only in a neutral medium (e.g., pH 6.8). 

Divalproex sodium is comprised of sodium valproate and valproic acid. The delayed-release and extended-release formulations are converted in the small intestine into valproic add, which is the systemically absorbed form. It was developed as an antiepileptic drug, but also has efficacy for mood stabilization and migraine headaches. It is FDA-approved for the treatment of the manic phase of bipolar disorder. It is generally equal in efficacy to lithium and some other drugs for bipolar mania. It has particular utility in bipolar disorder patients with rapid cycling, mixed mood features, and substance abuse comorbidity. Although not FDA-approved for relapse prevention, studies support this use, and it is widely prescribed for maintenance therapy. Divalproex can be used as monotherapy or in combination with lithium or an antipsychotic drug.31... 

Over the years, dissolution testing has expanded beyond ordinary tablets and capsules—first to extended-release and delayed-release (enteric-coated) articles, then to transder-mals, multivitamin and minerals products, and to Class Monographs for non-prescription drug combinations. (Note at the time, sustained-release products were being tested, unofficially, in the NF Rotating Bottle apparatus). 

Curran MP, Keating GM. (2005) Mycophenolate sodium delayed release Prevention of renal transplant rejection. Drugs 65 799-805. 

Swelling sustained-release coating polymers such as Eudragit NE 30 D, i.e. poly(ethyl-acrylate-methylmethacrylate) [101,102] or Eudragit RS [90], lead to a delay in drug release which is dependent on the thickness of the coating since these films have slow rates of swelling. 

Absorption - /a pro c acid is rapidly and almost completely absorbed from the Gl tract. Absorption of the drug is delayed but not decreased by administration with meals administration of the drug with milk products does not affect the rate or degree of absorption. The bioavailability of valproate from divalproex sodium delayed-release tablets and capsules containing coated particles has been shown to be equivalent to that of valproic acid capsules. 

Rheumatoid arthritis (RA delayed-release tablets) In the treatment of patients with RA who have responded inadequately to salicylates or other nonsteroidal anti-inflammatory drugs (NSAIDs). 

Give the drug in evenly divided doses over each 24-hour period intervals between nighttime doses should not exceed 8 hours, with administration after meals recommended when feasible. Swallow delayed-release tablets whole do not crush or chew. Experience suggests that with daily dosages of at least 4 g, the incidence of adverse effects tends to increase. 

Despite the problems posed by the pharmacokinetic and physicochemical characteristics of ibuprofen (small therapeutic window, erratic absorption owing to its poor solubility, etc.), this pulsed release system results in good separation of the two plasma peaks (indicating that there is in fact delayed release of the second drug dose) at the desired concentrations. 

Delayed release can also be applied for chronotherapeutic dosing, whereby the drug is administered in sync with the body s internal circadian rhythm. Verelan PM is an example of chromotherapeutic formulation that utilizes the combination of water-soluble polymers (povidone and gelatin) in conjunction with insoluble polymers (shellac). 

Delayed Release Release of a drug (or drugs) at a time other than immediately following oral administration. 

Enteric Coated Intended to delay the release of the drug (or drugs) until the dosage form has passed through the stomach. Enteric coated products are delayed release dosage forms. 

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