Transdermal Drug Delivery Systems (TDDSs) Overview

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Questions and Answers

What is the primary function of TDDSs?

To support the passage of drug substances through the skin and into the systemic circulation (correct)

To deliver drugs directly into the bloodstream

To control the rate of drug absorption in the gut

To enhance drug metabolism in the liver

What is the purpose of the polymer matrix in monolithic systems?

To enhance drug solubility in the skin

To prevent drug degradation in the skin

To control the rate of drug release for percutaneous absorption (correct)

To increase the surface area of the skin for absorption

What determines the rate of drug decline in monolithic systems with no excess drug?

The solubility limit of the stratum corneum (correct)

The concentration of drug in the device

The thickness of the skin

The surface area of the skin

What is the advantage of monolithic systems with excess drug?

They ensure continued saturation at the stratum corneum Signup and view all the answers

How are individual dosage units prepared in monolithic systems?

By cutting and assembling the gelled matrix Signup and view all the answers

What is the purpose of the backing layer in TDDSs?

To provide structural support to the device Signup and view all the answers

What is the difference between monolithic and membrane-controlled systems?

The presence or absence of a drug matrix layer Signup and view all the answers

What is the significance of Figures 11.8 to 11.10?

They depict the manufacture of TDDSs Signup and view all the answers

What is the primary purpose of having an excess of drug in most TDDSs?

To ensure continuous drug availability and absorption Signup and view all the answers

What is the role of the rate-controlling membrane in membrane-controlled transdermal systems?

To control the release rate of the drug Signup and view all the answers

What is the advantage of membrane-controlled systems over monolithic systems?

The release rate of drug remains constant as long as the drug solution in the reservoir remains saturated Signup and view all the answers

What is the purpose of placing a small quantity of drug in the adhesive layer in membrane-controlled systems?

To initiate prompt drug absorption and pharmacotherapeutic effects on skin placement Signup and view all the answers

What are the two possible rate-controlling mechanisms in TDDSs?

The artificial and natural membranes Signup and view all the answers

What is the function of the occlusive backing membrane in TDDSs?

To protect the system from environmental entry and from loss of drug from the system or moisture from the skin Signup and view all the answers

What is the difference between preconstructing the delivery unit and lamination in membrane-controlled systems?

Preconstructing is a single-step process, while lamination is a continuous process Signup and view all the answers

What determines the rate of drug transport in TDDSs?

The artificial or natural (skin) membranes Signup and view all the answers

Study Notes

Transdermal Drug Delivery Systems (TDDSs)

Designed to support the passage of drug substances from the surface of the skin through its various layers and into the systemic circulation.

Configuration and Composition of TDDSs

May be categorized into two types: monolithic and membrane-controlled systems.
Monolithic systems:
- Incorporate a drug matrix layer between the backing and frontal layers.
- The drug matrix layer is composed of a polymeric material in which the drug is dispersed.
- The polymer matrix controls the rate at which the drug is released for percutaneous absorption.
- May be of two types: with or without an excess of drug with regard to its equilibrium solubility and steady-state concentration gradient at the stratum corneum.
Membrane-controlled systems:
- Designed to contain a drug reservoir, or pouch, usually in liquid or gel form; a rate-controlling membrane; and backing, adhesive, and protecting layers.
- Examples: Transderm-Nitro (Summit) and Transderm Scop (Baxter).

Characteristics of Monolithic Systems

The rate of drug release is controlled by the polymer matrix.
The matrix may be produced in sheet or cylindrical form, with individual dosage units cut and assembled between the backing and frontal layers.
Most TDDSs are designed to contain an excess of drug and thus have drug-releasing capacity beyond the time frame recommended for replacement.

Characteristics of Membrane-Controlled Systems

The release rate of drug through the controlling membrane remains constant as long as the drug solution in the reservoir remains saturated.
A small quantity of drug is frequently placed in the adhesive layer to initiate prompt drug absorption and pharmacotherapeutic effects on skin placement.
May be prepared by preconstructing the delivery unit, filling the drug reservoir, and sealing or by lamination, a continuous process of construction, dosing, and sealing.

Rate-Controlling Mechanism

Either the drug delivery device or the skin may serve as the rate-controlling mechanism.
If the drug is delivered to the stratum corneum at a rate less than the absorption capacity, the device is the controlling factor.
If the drug is delivered to the skin area to saturation, the skin is the controlling factor.

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Description

This quiz covers the basics of Transdermal Drug Delivery Systems, including their composition, configuration, and types. It also touches on their manufacture and functionality.