Delayed-release

Some additives can suppress dissociation of CyD complexes. Morphine occurs naturally in the opium poppy. It is a potent narcotic analgesic, and its primary clinical use is in the suppression of moderately severe pain. In patients with vomiting, a rectal dosage form such as a suppository should be usefiil, especially a prolonged-release-type suppository. We have demonstrated that a combination of a-CyD and xanthan gum, a polysaccharide-type polymer with high swelling capacity, enhanced rectal absorption of morphine in rabbits, when administered to rabbit s rectum in the form of Witepsol H-15 [81] hollow-type suppositories. The combination of CyDs and viscous polymers may be useful for optimizing the trans-mucosal delivery of morphine [81]. 

During the dissolution process, the complex of y-CyD with diazepam showed an immediate-release profile, but the amount of the drug dissolved gradually decreases through the dissociation of the complex owing to its low stabihty constant 

A combination of CyDs with absorption enhancers can enhance bioavailabUity in various routes. A number of attempts have been made to enhance the absorption of Class III dmgs, induding not only prostaglandin but also peptides and proteins. One of the methods of improving their bioavailability is to use absorption enhancers. Prostaglandins are chemically unstable and poorly penetrative in epidermis and dermis, and some means of solving these defidencies of prostaglandins are required. 

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ASA appears to be the active component of sulfasalazine without the sulfa component, and is free of the serious side effects seen with sulfasalazine. It is used orally, in a delay-release formulation, as a retention enema, and as a suppository. It is well tolerated in most patients. 

Although the varied uses for which DIR couplers are employed call for precise control over where the inhibitor diffuses, the very complexation mechanism by which inhibitors work would seem to preclude such control. The desired ability to target the inhibitor can be attained by the use of delayed release DIR couplers, which release not the inhibitor itself, but a diffusable inhibitor precursor or "switch" (Fig. 16) (98). Substituents (X, R) and stmctural design of the precursor permit control over both diffusivity and the rate of inhibitor release. Increasing the effective diffusivity of the inhibitor, however, means that more of it can diffuse into the developer solution where it can affect film in an undesirable, nonimagewise fashion. This can be minimized by the use of self-destmcting inhibitors that are slowly destroyed by developer components and do not build up or "season" the process (99). 

Fig. 16. Reaction of a delayed release DIR coupler and oxidized developer (Dev ). A delayed released DIR coupler permits fine-tuning of where and when the development inhibitor (In) is generated by releasing a diffusible inhibitor precursor or "switch" as a function of image formation. This permits control...

Encapsulated Flocculants - A recent innovation in commercially available flocculants is a counter ionic system, where one charged moiety is encapsulated and suspended in the counter charged product. This facilitates a mechanism of delayed release of the encapsulated product. 

Large LOCA w. potential for delayed release after steam blowdown 1 ur. ... 

Rheologic measurements conflrmed that a soluble delayed-release acid could be used to convert a borate-crosslinked fluid into a linear gel [1353]. 

D. B. Acker and F. Malekahmadi. Delayed release breakers in gelled hydrocarbons. Patent US 6187720, 2001. 

P. C. Harris and S. J. Heath. Delayed release borate crosslinking agent. Patent EP 594364, 1994. 

Comparable daily doses of PPIs are omeprazole 20 mg = esomeprazole 20 mg = lansoprazole 30 mg = rabeprazole 20 mg = pantoprazole 40 mg. The PPIs degrade in acidic environments and are therefore formulated in delayed-release capsules or tablets.16 Lansoprazole, esomeprazole, and omeprazole contain enteric-coated (pH-sensitive) granules in a capsule form. For patients unable to swallow the capsule or in pediatric patients, the contents of the capsule can be mixed in applesauce or placed in orange juice. If a patient has a nasogastric tube, the contents of an omeprazole capsule can be... 

Asacol Delayed-release resin tablet 400 mg 1.6-4.8 g Distal ileum and colon... 

Prozac No Delayed-release capsule — 90 Once weekly... 

Syrup/suspension/ solution Extended-release/ enteric-coated tablets Faster rate of absorption 100% Delayed absorption 60-90% Faster rate of absorption Delayed absorption 89% of the suspension and less than regular-release tablets Unknown NA Faster rate of absorption than tablets Extended-release 90% of intravenous dose. Delayed-release 81-90% of intravenous dose Delayed absorption with delayed-release tablets valproate is rapidlyconverted to VPA in the stomach, then is rapidly and almost completely absorbed from the Gl tract NA NA... 

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... 

BA, bioavailability BP, blood pressure CEE, conjugated equine estrogens CrCI, creatinine clearance CYP450, cytochrome P-450 DR, delayed-release Ml, myocardial infarction PV, per vagina Sign., significantly TD, transdermal TE, thromboembolism. 

Diclofenac 50 mg 2-3 times daily 75 mg twice daily (delayed-release) 100 mg once daily (extended-release) 150... 

Shellac Aqueous if pH 7.0 May delay release too long high batch-to-batch variability... 

Zegerid is a combination product containing omeprazole 20 or 40 mg with sodium bicarbonate in immediate-release oral capsules and powder for oral suspension. It should be taken on an empty stomach at least 1 hour before a meal. Zegerid offers an alternative to the delayed-release capsules or the IV formulation in adult patients with nasogastric tubes. 

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). 

If a delayed-release formulation is taken around 5 p.m., it will have progressed through to the ascending colon by the time the patient goes to bed. Quiescence of propulsive move-... 

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