US FDA stated in its new guidelines on transdermal drug delivery system and related drug delivery systems that the initial drug load concentration has tremendous potential for impacting quality of product its safety and efficacy and it has great potential for drug abuse.
There are many advantages and disadvantages of transdermal drug delivery system TDDS , like a drug can be administered without pain to patient, patients to like the dosage form greatly as they wont feel as they are on medication, and a constant plasma drug concentration can be easily achieved for a drug for a longer period of time without giving the untoward effect of initial higher plasma level of a drug as in case of conventional dosage forms, also drug escape the first pass metabolism through transdermal drug delivery , some a critical drugs which are known to save life are also administered as Transdermal patches for example nitroglycerin in congestive cardiac diseases.
There are some serious effects observed in resent time, like accidental high dose of a drug up on accidental sticking on handling or accidental contact with skin which has lead individual serious and to fatal conditions some times a life threatening one.
The fatal untoward effects are also seen in health care providers which accidentally handled the patches and got drug dose from remaining drug load from the used transdermal drug delivery patch.
The important factor.
The drug concentration which is required to be loaded on to a Transdermal drug delivery or related drug delivery systems is very high than that of the actual drug being absorbed and required to be achieved in to plasma of a patient.
US FDA guidelines for Transdermal drug delivery patches and related drug delivery systems
In order to finally achieve consistent low residual drug with the desired quality of the Transdermal drug delivery systems ,
1. US FDA requires a drug manufacturers to submit the initial loaded drug concentration in the transdermal drug delivery patch and related drug delivery systems , be provided in the application for investigational new drug applications (INDs), new drug applications (NDAs), abbreviated new drug applications (ANDAs), and supplemental new drug applications (sNDAs) for TDDS, TMDS, and topical patch products.
2.US FDA now requires that the all justifications for initial drug load or concentration should be included in the application.
3.It also states that a proper scientific risk based approach must be taken to minimize the drug residue in the system so that a lowest possible concentration remains in the system.
4.The amount of residual drug in the transdemanl drug delivery system must not exceed than those already approved by FDA .
5. US FDA also requires that the information of product and process development and how the final formulation is justified should be given in the common technical document (CTD) formatted application in section for Pharmaceutical Development.
US FDA has put emphasis on following points
1.) Quality By Design Concept
2.) Minimizing Residual Drug
The transdermal drug delivery patches and related products , be developed with the intention of giving efficacy and safety as well,
The quality by design concept basically requires a formulator to plan for a desired quality, quality of a drug can be best achieved when it is planed than when it monitored.
Planing of quality of a drug product through logical application of past findings and research data and chemistry of drug molecule and exceipients being used, to achieve minimum drug load and this can lead to achieve minimum residual drug in transdermal drug delivery systems after use. Which will ensure that the abuse potential of the transdermal drug delivery systems are taken care of.
Good Manufacturing Practices
Liposome drug delivery system