Question

Tissue engineering question:

Describe two of the three types of drug delivery systems with a brief explanation of the drug release mechamism in each.

Answer 1

Ans.

• Approaches, methods, formulations, technologies and systems required for delivering a pharmaceutical compound in the body to achieve it's intended or desired therapeutic effects, is called as drug delivery.
• Ways used for drug delivery are called as drug delivery systems.
• Several drug delivery systems can control the rate of drug release as well as site of drug release.
• Some types of drug delivery systems are;

1). Oral drug delivery systems.

• It is the oldest, commonest and one of the most extensively used system of drug delivery.
• This system has several advantages associated with it such as convenience, ease of administration and increased patient compliance, all of which make it a suitable system of drug delivery.
• In immediate release oral drug delivery system, therapeutic plasma concentraton of drug is often constantly changing and unpredictable due to little or no control over drug release from the dosage forms.
• Modified relaese (MR) form is another example of oral drug delivery system which can regulate the release characteristics of site and time of drug release.
• Most of the oral drug delivery system can be categorized in matrix, reservior, osmotic systems or ion-exchange resins.

2). Pilmonary drug delivery systems;

• This drug delivery system is mostly used for the treatment of respiratory systems diseases.
• Drugs can also be delivered into the systemic circulation by utilising the lung's natural ability of transfering molecules into the blood.
• It is a non-invasive and less painful alternative to the painful injectibles and can produce rapid onset of drug action and good systemic bioavailability of drug.
• Inhalation devices can be categorized into 3 groups;
• Pressureized meter dose inhalers (MDIs) ; drug is contained as a solution or suspension of fine particles in a liquid propellant under high pressure and emitted from metering valve through an orifice.
• Nebulizers ; large quantities of small droplets can be generated and delivered to pulmonary system without need of any propellant
• Dry powder inhalants (DPI) ; It is a device that require some procedure to deliver a certain amount of drug in powdered form to the lungs of patients.

3). Transdermal drug delivery systems (TDDS);

• This sytem deliver drug at a predefined rate in systemic circulation through skin.
• TDDS avoid the interference of liver and gastrointestinal tract on drug metabolism.
• So, amount required of active ingredient for TDDS is much lesser then that required for oral drug delivery systems.
• Constant drug level of drug in blood can be maintained with this system and patients compliance is also very good.