Solid Modified Release

Delayed or extended release

Modified release products can either be

Extended release products

Designed to released their medication in a controlled manner, at a predetermined rate, duration, and location to achieve and maintain optimum therapeutic blood levels of drug

Delayed release products

are enteric coated tablets or capsules designed to pass through the stomach unaltered, later to release their medication within the intestinal tract

Multiple daily dosing

inconvenient for the patient and can result in missed doses, made-up doses, and noncompliance with the regimen.

provide an immediate release of drug that promptly produces the desired therapeutic effect, followed by gradual release of additional amounts of drug to maintain this effect over a predetermined period

How do extended-release products work?

loss of flexibility in adjusting the drug dose and/or dosage regimen and a risk of sudden and total drug release, or dose dumping, due to a failure of technology

Disadvantages of extended-release system

minimum toxic concentrations of drug may be reached, with toxic side effects resulting.

What happens if drugs are administered too frequently?

periods of subtherapeutic drug blood levels or those below the minimum effective concentration may result, with no benefit to the patient.

What happens if doses are missed?

Controlling rate of release eliminates peaks and valleys of blood levels

Less fluctuation in drug blood levels

Extended-release products frequently deliver more than a single dose, hence may be taken less often than conventional forms.

Frequency reduction in dosing

With less frequency of dosing, a patient is less apt to neglect taking a dose; also greater convenience with day and night administration

Enhanced convenience and compliance

Because of fewer blood level peaks outside therapeutic range and into toxic range, adverse side effects are less frequent.

Reduction in adverse side effects

Although initial cost of extended-release dosage forms may be greater than for conventional forms, overall cost of treatment may be less because of enhanced therapeutic benefit, fewer side effects, and reduced time for health care personnel to dispense and administer drugs and monitor patients.

Reduction in overall health care costs

modified release

general use to describe dosage forms having drug-release features based on time, course, and/or location that are designed to accomplish therapeutic or convenience objectives not offered by conventional or immediate release forms.

Extended Release

allows a reduction in dosing frequency from that necessitated by a conventional dosage form, such as a solution or an immediate-release dosage form

Delayed release

designed to release the drug at a time other than promptly after administration.

Repeat action

contain two single doses of medication, one for immediate release and the second for delayed release.

Target release

describes drug release directed toward isolating or concentrating a drug in a body region, tissue, or site for absorption or for drug action.

Characteristics of Drug Candidates for Extended-Release Products

They exhibit neither very slow nor very fast rates of absorption and excretion.

They are uniformly absorbed from the gastrointestinal tract.

They are administered in relatively small doses.

They possess a good margin of safety.

They are used in the treatment of chronic rather than acute conditions.

Drugs with very short half-lives

are poor candidates for ER because of the large quantities of drug required for such a formulation

Drugs prepared in extended-release forms

must have good aqueous solubility and maintain adequate residence time in the gastrointestinal tract.

Drugs with large single doses

are not suitable for ER because the tablet or capsule needed to maintain a sustained therapeutic blood level of the drug would be too large for the patient to swallow easily.

Therapeutic index

most widely used measure of the margin of a drug's safety

Drugs for acute conditions

require greater adjustment of the dosage by the physician than that provided by extended-release products.

extended drug action

achieved by affecting the rate at which the drug is released from the dosage form and/or by slowing the transit time of the dosage form through the gastrointestinal tract

the starting granules of material may be composed of the drug itself.

What happens if the dose of the drug is large?