How long is sustained release

Difference between Sustained Release and Prolonged Release Tablets Both of these are delayed release tablets having different properties in their drug release timings but have considerable differences. Ankur Choudhary Print Question Forum 2 comments. The words sustained release and prolonged release can be used interchangeably because they mean the same thing.

But the difference between sustained release tablets and prolonged release tablets is surely evident. Sustained release tablets are in a form of dosage where a drug is administered to a patient at a given or calculated rate with the aim of maintaining a certain concentration of the administered drug over a specific period of time into the patient's system while reducing possible side effects.

While prolonged release tablets are meant to effect after some time from the moment they are administered and they are known to be released in small portions over a long period of time with no specifications to time or rate of concentration.

Sustained release tablets are more of a controlled release. This happens where a capsule is made and is filled with other small pellets of drugs with different coatings that will not dissolve immediately once they are administered but will take time to release their contents at a predetermined rate.

While prolonged release tablets and capsules are aimed at delaying in administration and dissolve at a slower and constant rate into the body system with the benefit of not having to take the drugs more frequently. This is mostly for patients with chronic illness they are able to take drugs less number of times in a day. Prolonged release in oral dose formulations is mostly time-dependent and delayed release. Often prolonged release is targeted and intended to heal certain areas of the body system that can not be cured effectively by other ordinary drugs and ointments.

This is different with the sustained release tablets as they are often administered slowly to maintain a particular amount of drug levels into the bloodstream during a drug administration or injection so as to maintain an efficient healing process.

Related: Solid Pharmaceutical Dosage Forms - Tablets Mostly prolonged release tablets are administered to heal certain parts or target body parts. Once they are introduced into the blood system they are released either on the specific part or near the target site that needed the cure. While the sustained release does not target particular body sites or parts.

Sustained release tablets are often time-release drugs, they can either be released immediately or in small amounts after administration. TR nonspecifically indicates time-release; propranolol has been marketed as a TR formulation. DR indicates delayed-release, as in enteric-coated tablets; valproate is an example of a drug that is available as a delayed-release formulation.

SR indicates sustained-release; this is a rather generic term that is used to describe gradual release in the formulations of drugs that include alprazolam, bupropion, clomipramine, quetiapine, and others.

CR indicates controlled release along with the special property of the release following a specific, predetermined pattern. There are dozens of ways in which drugs can be formulated to achieve the desired property of release, 13 , 14 some of which may even characterize the name of the formulation, as with methylphenidate OROS osmotic controlled-release oral delivery system.

In the early era of time-release formulations, the entire tablet was formulated in concentric layers of medication alternating with barrier layers; as a barrier gradually dissolved, it released the medication layer below it and exposed the next barrier layer. In later types of formulation, individual granules of medication were barrier-coated in such concentric layers.

Present-day formulations are more complex. Most time-release formulations lose their time-release property and become immediate-release formulations if the integrity of the pill or capsule is damaged; this is why the manufacturer may recommend that the medication be swallowed whole without chewing, breaking, or crushing. Therefore, most time-release formulations cannot be chewed and swallowed by patients who have difficulties in swallowing, or powdered and administered with food, or powdered and administered through a nasogastric tube.

If individual granules of a time-release pill are barrier-coated, as described earlier, then even if the pill is broken and administered, each piece of the pill will retain the time-release property of the parent pill. As an example, at least 1 sustained-release alprazolam formulation has this property. As an example, extended-release memantine capsules can be opened and their contents sprinkled on food. If supporting literature is not available, the only way of finding out is to obtain the information directly from drug company representatives.

Other characteristics of the formulation, such as whether it is a hour formulation or a hour formulation, and how much of the drug is released, where, and when, would also be described by the manufacturer in the supporting literature. Physicians need to be aware of this information in order to know how best to prescribe the drug.

Some of the advantages of time-release formulations have already been considered in an earlier section. These include reduction in GI adverse effects, reduction in adverse effects associated with peak blood levels, and extension of the effective half-life of the drug. There are other advantages, too. These are briefly considered here. Once-daily dosing is feasible with most time-release formulations. This increases the convenience of dosing and can improve drug compliance.

Taking controlled-release carbamazepine which can be dosed twice a day, whereas immediate-release carbamazepine would need to be dosed thrice a day is convenient because it obviates the need for the afternoon dose; if this afternoon dose is forgotten, the patient may suffer a breakthrough seizure should the medication have been prescribed for the management of a seizure disorder.

Sustained-release dosing is also associated with relatively uniform blood levels of the drug across the course of the day; peaks and troughs in blood levels, noticeable with immediate-release dosing, are diminished. The advantage of blunted peaks is that the risk of adverse effects, associated with the peaks, is diminished.

The advantage of shallower troughs is that the risk of loss of efficacy or the appearance of withdrawal symptoms , associated with a fall in blood levels, is minimized. When adverse effects are fewer, compliance is improved. A special note is that with sustained-release formulations of methylphenidate, the child usually does not need to take an additional dose at school. So, taking a medication in front of peers will not cause embarrassment to the child, and the school dose will not be forgotten or lost or misused by other children.

Other advantages of this formulation have also been described. Time-release formulations are associated with certain disadvantages. As a result of the gradual release, in most patients the tablet reaches the colon before complete dissolution. Absorption from the colon is not as good as that from the small intestine.

As a consequence, particularly with once-daily formulations, small quantities of medication are excreted unabsorbed in the form of pellets in the feces. The cost of therapy with time-release formulations is therefore slightly higher not only because of the cost of the formulation but also because of the need for the extra dose. Whereas incomplete absorption is a problem with most time-release formulations, it does not appear to be an issue with sustained-release and extended-release formulations of bupropion.

In persons with intestinal hurry syndromes, time-release formulations are associated with poor bioavailability because the tablet rapidly reaches the colon and may even be excreted in feces long before dissolution is complete. Time-release formulations should therefore be avoided in patients with chronic intestinal hurry syndromes such as irritable bowel syndrome.

When patients develop transient intestinal hurry syndromes, such as acute gastroenteritis, the prescription should temporarily be shifted from a time-release formulation to an immediate-release formulation until bowel functioning normalizes, lest the efficacy of the medication be lost. Decreased absorption of medication for a few days is rarely a problem in most disorders, but it can be an issue, for example, if the patient is taking the medication for seizure disorder when lower medication absorption could result in a breakthrough seizure or if the drug is like venlafaxine or alprazolam when drug discontinuation symptoms may manifest.

An important consideration and one that is unresolved in the literature is whether time-release formulations are well absorbed in persons whose normal pattern is to have 2 or more bowel movements spread across the course of the day. If these patients have greater intestinal motility, they may excrete unabsorbed pills faster, resulting in lower bioavailability of the drug.

In such patients, then, unless blood levels confirm satisfactory bioavailability, a relapse that occurs may be due to poor absorption rather than to true inefficacy of the medication in that patient. When large doses of the drug are administered in a single time-release pill, the size of the pill may be large, resulting in swallowing difficulties with some pills and in some patients.

At least 1 brand of extended-release divalproex 1, mg suffers from this limitation; as with most other time-release formulations, this tablet cannot be broken because that would destroy its time-release property.

The advantages described in earlier sections provoke the thought that all medications should ideally be administered as time-release formulations. This is, however, unnecessary with drugs that have long half-lives because the long-half life itself ensures uniformity of blood levels across the course of the day.

For this reason, it is unnecessary to formulate sustained-release aripiprazole. This is also why the need for extended-release memantine is a puzzle. Both aripiprazole 20 and memantine 21 have a half-life of about 3 days. Time-release formulations may not necessarily do what they are prescribed to do. For example, a sustained-release formulation of clomipramine, administered at night, may merely prolong the duration of the morning hangover instead of preventing it.

The physician may then prefer to revert to the immediate-release formulation, or, as a possible strategy, the sustained-release formulation can be dosed in the late evening instead of at bedtime.

Similarly, the choice between immediate-release and sustained-release or extended-release formulations of quetiapine will depend on whether it is more important to promote nighttime sleep or to avoid the next-day hangover, and whether the purpose is served by the formulation selected.

As with all prescribing, an element of trial and error is inevitable in discovering what works best. Passing medication shells in the feces does not necessarily imply poor absorption. Sometimes, insoluble parts of a controlled-release formulation may be spotted in the stools; these are known as ghost pills, and they are empty.

Ghost pills have been described with several formulations, such as extended-release venlafaxine. Interpretation should be based on blood level assessments, clinical response, and other available information. Patients who overdose with time-release formulations may experience delayed or prolonged toxicity. This may be seen, for example, with sustained-release lithium 23 and sustained-release clomipramine. Finally: time-release formulations vary widely in nature and purpose. Readers are referred to the review by Keith 25 for a discussion of specific time-release psychotropic formulations.

Each month in his online column, Dr Andrade considers theoretical and practical ideas in clinical psychopharmacology with a view to update the knowledge and skills of medical practitioners who treat patients with psychiatric conditions. Financial disclosure and more about Dr Andrade.

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