Related Experiment Video
Updated: Jun 6, 2026
08:38
Renal Capsule Xenografting and Subcutaneous Pellet Implantation for the Evaluation of Prostate Carcinogenesis and Benign Prostatic Hyperplasia
Published on: August 28, 2013
Controlled delivery of testosterone from smart polymer solution based systems: in vitro evaluation
1Department of Pharmaceutical Sciences, College of Pharmacy, North Dakota State University, Fargo, ND 58105, USA.
International Journal of Pharmaceutics
|April 26, 2005
Summary
Injectable polymer systems using phase-sensitive and thermosensitive materials offer controlled release of testosterone (TSN). These systems demonstrate potential for long-term injectable implants, with release rates influenced by formulation components and drug loading.
Area of Science:
- Polymer Science
- Biomaterials Engineering
- Pharmacology
Background:
- Controlled drug delivery systems are crucial for maintaining therapeutic drug levels.
- Testosterone (TSN) replacement therapy often requires sustained release formulations.
- Injectable polymeric systems offer advantages for long-term drug delivery.
Purpose of the Study:
- To develop injectable, controlled-release delivery systems for testosterone (TSN).
- To utilize phase-sensitive and thermosensitive polymers for TSN delivery.
- To evaluate the influence of formulation variables on in vitro TSN release kinetics.
Main Methods:
- Phase-sensitive systems: Poly(lactide) (PLA) with benzyl benzoate (BB) and benzyl alcohol (BA) solvents.
- Thermosensitive systems: Poly(lactide-co-glycolide)-poly(ethylene glycol)-poly(lactide-co-glycolide) (PLGA-PEG-PLGA) triblock copolymers.
- In vitro release studies conducted in phosphate-buffered saline (pH 7.4) with Tween-80, analyzed via HPLC.
Main Results:
- Both phase-sensitive and thermosensitive systems achieved controlled (zero-order) in vitro TSN release.
- Benzyl alcohol addition (15%) significantly increased TSN release rate in phase-sensitive systems.
- Increased drug loading enhanced TSN release rate.
- In thermosensitive systems, longer hydrophobic PLGA block lengths decreased TSN release rate.
Conclusions:
- Phase-sensitive and thermosensitive polymers are suitable for developing prolonged-release injectable implants for TSN.
- Formulation parameters, including solvent composition and polymer architecture, effectively modulate TSN release profiles.
- These findings support the development of advanced injectable drug delivery systems for hormone therapy.
Related Concept Videos
01:30Modified-Release Drug Delivery Systems: Stimuli-Activated
Stimuli-activated drug delivery systems are designed to release drugs in response to specific physical, chemical, or biological stimuli. These systems often utilize hydrogels—three-dimensional, hydrophilic polymer networks capable of swelling in aqueous environments and retaining significant fluid volumes. Upon exposure to particular stimuli, these hydrogels undergo structural transitions that allow the embedded drug to be released. Due to this adaptive behavior, such systems are also called...
01:24Modified-Release Drug Delivery Systems: Site-Targeted
Site-targeted drug delivery systems enhance therapeutic efficacy while minimizing systemic toxicity and treatment costs. Unlike conventional methods, these systems ensure precise drug delivery, improving bioavailability and reducing side effects. Targeted drug delivery is classified into three levels. First-order targeting directs drugs to the capillary beds of specific organs or tissues. Second-order targets specific cell types, such as tumor cells, using receptor-mediated interactions.
01:24Site-Targeted Drug Delivery Systems: Polymeric Carriers
Polymeric carriers enhance targeted drug delivery by increasing efficacy while minimizing off-target effects. These carriers comprise a biodegradable polymeric backbone integrated with functional elements that enable targeting, improve physicochemical properties, and regulate drug release.Targeting MechanismsThe targeting ability of polymeric carriers is mediated by a homing device, which is a molecular recognition component designed to selectively bind to specific tissues or cells. Monoclonal...
01:28Parenteral Drug Delivery Systems: Injectables, Implants, and Infusion Devices
Parenteral drug delivery systems play a crucial role in modern therapeutics by enabling the direct administration of drugs into the systemic circulation, bypassing the gastrointestinal tract. These systems are particularly valuable for poorly absorbed oral medications that are unstable in the digestive environment or require rapid onset or sustained therapeutic levels. Delivery is achieved through intravenous, intramuscular, or subcutaneous routes, each selected based on the drug's properties...
01:18Transdermal Drug Delivery Systems
Transdermal drug delivery systems (TDDS) enable the controlled release of drugs across the skin into systemic circulation. They are particularly advantageous for drugs with short half-lives or narrow therapeutic indices, as they maintain consistent plasma concentrations and reduce the risk of subtherapeutic or toxic levels.TDDS are categorized into monolithic, reservoir, and mixed systems. Monolithic systems embed the drug in a polymer matrix, where diffusion governs release. Reservoir systems...
01:21Intrauterine Drug Delivery Systems
Controlled-release systems for intravaginal and intrauterine drug delivery have been developed primarily for the administration of contraceptive steroid hormones. These delivery routes circumvent first-pass hepatic metabolism, thereby enhancing bioavailability and allowing for reduced systemic dosages compared to oral administration. Such approaches contribute to improved therapeutic efficacy and patient compliance, particularly in long-term contraceptive regimens.Intravaginal Drug Delivery...