Injections are not a solid dosage form, but rather a liquid or suspension that is administered directly into the body.

Drug delivery systems serve multiple functions, including protecting the drug from degradation, controlling its release, and enhancing its absorption.

Transdermal patches are an example of a passive drug delivery system, where the drug is released slowly and continuously through the skin.

In sustained-release tablets, the drug is released primarily through diffusion, where the drug molecules move from an area of high concentration (inside the tablet) to an area of low concentration (the surrounding environment).

The bioavailability of a drug is influenced by various factors, including the dosage form, route of administration, and physicochemical properties of the drug.

Controlled-release drug delivery systems aim to maintain a constant drug concentration in the body, reduce the frequency of dosing, and improve patient compliance.

Immediate-release systems are not a type of controlled-release drug delivery system, as they release the drug rapidly and completely upon administration.

Targeted drug delivery systems offer several advantages, including increased drug concentration at the target site, reduced systemic side effects, and improved patient compliance.

Liposomes, nanoparticles, and monoclonal antibodies are all examples of targeted drug delivery systems.

In liposomal drug delivery systems, the drug is encapsulated within liposomes (small vesicles), and the release of the drug occurs primarily through endocytosis, where the liposomes are taken up by cells.

Particle size reduction, salt formation, and co-solvency are all common methods for enhancing the solubility of a poorly water-soluble drug.

In transdermal patches, the drug is released primarily through diffusion, where the drug molecules move from an area of high concentration (inside the patch) to an area of low concentration (the skin).

The rate of drug release from a matrix system can be affected by various factors, including drug loading, polymer type, and pH of the environment.

In osmotic drug delivery systems, the drug is released primarily through osmosis, where water molecules move from an area of high concentration (outside the system) to an area of low concentration (inside the system), causing the drug to be released.

Intravenous is not a route of drug administration, but rather a method of administration where the drug is injected directly into a vein.