Solide: Oral Controlled Release Systems

What is Oral Modified Release Dosage Forms

Modified release dosage forms modify the time course and/or location ofdrug  release for therapeutic benefit/patient convenience

What is the goal of Modified Release

he main goals of modified release formulations are:

•Maintenance of constant plasma profile:

–Improved efficacy

•Reduced dosing frequency

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•More convenient dosing

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•Improve patient adherence to therapy

What are the physiological factors influencing Modified Release Development of a drug

GI physiology

Elimination half life

Absorption site of the drug

Therapeutic index

Metabolism

What are drug factors influencing modified release development of a drug

Dose of drug

BCS classification

Ionisation

What are the main types of oral modified release dosage forms in clinical use

1. Matrices

2. Coated/ reservoir systems

What is matrix system

Drug substance is homogenously mixed into the rate controlling material(s) as a crystalline, amorphous or molecular dispersion.

Drug release occurs either by drug diffusion and/or erosion of the matrix system.

Matrices can be hydrophilic or lipophilic.

What is coated/ reservoir systems

Typically consists of a core containing solid drug orhighly  concentrated drug solution surrounded by afilm or  membrane of a rate controlling material.

The coating may be:

•Semi-permeable (insoluble)

•Hydrophilic (swellable) coating

•Eroding (lipidic)

State the mechanisms of drug release from modified release systems

Outline the osmotic pump systems

Osmotic pump tablets consist of either combined or separated drug and osmoticcompartments.

Two compartment systems have:

1.A drug compartment

2.An osmotically active compartment (containing cross-linked polymer)separated  from the drug by a membrane

The matrix is coated with a semi-permeable rate controllingmembrane.  A laser drilled hole allows drug release from the drug compartment.

name an example of osmotic pumps used to treat cardiovascular disease

Cardura

Procardia

What is polypill

•A polypill (fixed dose combination) is one ‘pill’ that contains a combination of3-  4 medications commonly used to treat heart disease and hypertension.