Author: Delly Ramadon, Maeliosa T. C. McCrudden, Aaron J. Courtenay & Ryan F. Donnelly
Transdermal drug delivery systems , research topic in pharmaceutical technology area, developed pharmaceutical products in global market, delivery routes, such as oral and parenteral, applications of transdermal technologies, transdermal drug delivery systems and enhancement strategies, development of first-generation transdermal products, drug/vehicle interactions, vesicles and particles, stratum corneum modification, energy-driven methods and stratum corneum bypassing techniques, suitable design and implementation of active stratum corneum bypassing methods, notably microneedle technology, transdermal delivery systems have been shown to deliver both low and high molecular weight drugs, microneedle technology platforms, intradermal delivery of drugs/biotherapeutics and therapeutic drug monitoring, strategy for improving transdermal delivery systems, drug delivery systems, Innovation in drug delivery systems is a key strategy employed to improve the bioavailability of active pharmaceutical ingredients (APIs), oral delivery systems offer benefits , such as dosage form variety, painless ease of administration, convenience, self-administration, high safety, and patient compliance , oral delivery systems have some limitations such as poor drug stability in the gastrointestinal tract and subjection to first pass metabolism. For instance, there is a possibility of drug degradation caused by enzymatic reaction or exposure to the acidic environment in the stomach, solubility issues of drugs in the intestinal fluid and their permeability through the intestinal membrane may act as rate limiting steps in drug absorption, causing low bioavailability these drawbacks are routinely observed in the delivery of peptide or protein-based drugs, as a result, intravenous (IV) injection is designated as one of the most promising delivery system for proteinaceous drugs, as it can achieve up to 100% bioavailability, accurate dosing and hepatic metabolism avoidance, injection can achieve up to 100% bioavailability, accurate dosing and hepatic metabolism avoidance, disadvantages are an invasive delivery method, causing pain, low patient compliance, and sharps waste disposal considerations add significant costs, transdermal drug delivery systems use the skin as the drug administration site, the administered drug is absorbed into the systemic circulation via blood vessels in the skin and then circulates around the body, transdermal drug delivery systems offer some advantages for patients, such as being less invasive (some methods are entirely noninvasive), first-pass metabolism avoidance, ease of application and administration, reduce frequency of administration, used for the delivery of different varieties of drugs, both hydrophilic and hydrophobic compounds, Drug absorption via the skin, application of drug-containing dosage forms onto the skin, drug will be released into the skin, Avoidance of significant pre-systemic metabolism (degradation in gastrointestinal tract (GIT) or by the liver) leading to bioavailability improvement, continuity of drug administration in transdermal patches permits the use of a drug with short biological half-life, possibility of sustained and controlled drug delivery over a prolonged period of time even drugs with narrow therapeutic window, Increased patient acceptance and compliance due to the reduction of dosing frequency , more uniform pharmacokinetic profiles of drugs with minimization of peaks-troughs in plasma-drug concentration, thus reducing the risk of toxic side effects, Ease of dose termination in case of any systemic or local adverse effect, providing an alternative to oral dosing in the circumstances of unconscious or nauseated patients, facilitating noninvasive mode of drug administration by avoiding the risk and inconveniences such as needle phobia associated with parenteral therapy, in spite of many potential advantages, transdermal patches has following limitations, essentiality of molecular weight <500 Da to ensure ease of diffusion across the SC, since solute diffusivity is inversely related to its size, Sufficient aqueous and lipid solubility, a Log P (octanol/water) in between 1 and 3 is required for the permeant to successfully traverse the SC and its underlying aqueous layers for systemic delivery to occur, drugs that require high blood levels cannot be administered as transdermal patches is mostly limited only to potent molecules (oral dose is <10 mg/day) , certain drugs, excipient, or components of transdermal patches may cause skin irritation and sensitization leading to erythema and edema, intra- or inter-personal variability in skin changes its barrier function, drug administration in transdermal patches permits the use of a drug with short biological half-life (24 h),
