Time-Release Medications

Rationale for Time-Release Medication

Some drugs are inherently long lasting and require only once-a-day oral dosing to maintain adequate drug blood levels and the desired therapeutic effect. Many other medications, however, are not inherently long lasting and require multiple daily dosing to achieve the desired therapeutic results. Multiple daily doses are inconvenient for the patient and can result in missed doses, made-up doses, and noncompliance with the medication's regimen.

Almost all medications marketed today are initially in what is called “immediate-release” or “rapid-release” preparations. These are medications that disintegrate and dissolve in 5 or 10 minutes. Immediate-release medications produce a relatively rapid and high concentration of the drug in the body (a burst), followed by an exponential decline in levels of the drug in the blood, a peak and valley (trough) effect. So when conventional immediate-release medications are taken on schedule, using more than one daily, they cause sequential drug blood-level peaks and troughs associated with the taking of each dose. When the doses are not taken on schedule, the resulting peaks and troughs produce less than optimal drug therapy. For example, if doses are administered too frequently, minimum toxic concentrations of the medication may be reached. If, on the other hand, doses are missed, periods of subtherapeutic drug blood levels (those below the minimum effective concentration) may result, with no benefit.

On the other hand, a typical time-release medication provides an immediate release of the drug that promptly provides the desired therapeutic effect followed by gradual release of additional amounts of the drug to maintain this effect over a predetermined period of time. Many of these medications are formulated in such a way that the active material is coated with some relatively insoluble material or film. So when we take them, the upper coating or film releases very slowly in the body with the slow release of active material over a period of time. Thus, the advantages of time-release medications include less fluctuation in drug blood levels, less frequent dosing, enhanced convenience and compliance, reduction of adverse side effects, and reduction in overall health care costs. The potential disadvantages include the possible toxicity or nonbiocompatibility of the materials used to enable the time-release properties of the medication, undesirable by-products of degradation of those materials, lack of control of dosage once ingested (once ingested, time-release medications deliver treatment continuously, rather than providing relief of symptoms and protection from adverse events solely when necessary), dangers of high drug-delivery levels, and toxicity resulting from any loss of integrity of the release characteristics of the medication.

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