Biorelevant In Vitro Performance Testing of Orally Administered Dosage Forms—Workshop Report

Biorelevant in vitro performance testing of orally administered dosage forms has become an important tool for the assessment of drug product in vivo behavior. An in vitro performance test which mimics the intraluminal performance of an oral dosage form is termed biorelevant. Biorelevant tests have been utilized to decrease the number of in vivo studies required during the drug development process and to mitigate the risk related to in vivo bioequivalence studies. This report reviews the ability of current in vitro performance tests to predict in vivo performance and generate successful in vitro and in vivo correlations for oral dosage forms. It also summarizes efforts to improve the predictability of biorelevant tests. The report is based on the presentations at the 2013 workshop, Biorelevant In Vitro Performance Testing of Orally Administered Dosage Forms, in Washington, DC, sponsored by the FIP Dissolution/Drug Release Focus Group in partnership with the American Association of Pharmaceutical Scientists (AAPS) and a symposium at the AAPS 2012 Annual meeting on the same topic.     

Reservoir Based Fentanyl Transdermal Drug Delivery Systems: Effect of Patch Age on Drug Release and Skin Permeation

Purpose  To understand and evaluate the stability and skin permeation profiles of fentanyl reservoir systems as a function of patch age. Methods  Drug release and skin permeation studies were performed using a modified USP apparatus 5 with a novel sample preparation technique. Results  The amount of fentanyl present in the EVA/adhesive layer (EAL) increased from about 17% of label claim (LC) at 5 months to 25% LC at 22 months. The increase in the drug concentration was mainly observed in the peripheral EAL. Simultaneously, the alcohol content of the patch decreased as a function of patch age. A significant effect of patch age on the drug content in the EAL and the drug release from the system was observed; however, skin permeation studies did not indicate an increase in drug delivery rate. Conclusions  Novel sample preparation technique with USP Apparatus 5 allowed determination of in vitro skin permeation rates for fentanyl transdermal patches with different designs. Permeation rates with cadaver skin as substrate were found not to change with patch age despite changing drug concentration in the EAL.     

Arachnoid cyst resulting in sixth nerve palsy in a child

A 2 year old presented with incomitant esotropia and abduction deficit consistent with sixth nerve palsy. Neuroimaging revealed an arachnoid cyst on the left. Neurosurgical shunting followed by strabismus surgery relieved the abduction deficit and esotropia. An arachnoid cyst may be a rare cause of acquired sixth nerve palsy and strabismus in children.     

Detection of undeclared erectile dysfunction drugs and analogues in dietary supplements by ion mobility spectrometry

An ion mobility spectrometry (IMS) method was developed to screen for the presence of undeclared synthetic erectile dysfunction (ED) drugs or drug analogues in herbal dietary supplements claiming to enhance male sexual performance. Ion mobility spectra of authenticated reference materials including three FDA approved drugs (sildenafil citrate, tadalafil, vardenafil hydrochloride trihydrate) and five previously identified synthetic analogues (methisosildenafil, homosildenafil, piperidenafil, thiosildenafil, thiomethisosildenafil) were measured to determine their reduced ion mobilities (K₀). All eight compounds exhibited reduced mobilities between 0.8257 and 1.2876 cm²/(V s). Twenty-six herbal products were then screened for the presence of these compounds, and 15 of the 26 products tested positive for the presence of ED drug or drug analogue adulterants based on their reduced ion mobilities. IMS results were compared against the results obtained from an independent LC/MS reference method for the identical samples. Herbal dietary supplements containing adulterants were classified with 100% accuracy and most of the adulterants were correctly identified by a comparison of the K₀ of the adulterant to the K₀ of the authenticated reference material. The results demonstrate that IMS is a viable method for screening herbal dietary supplements for the presence of ED drug or drug analogue adulterants.     

Transdermal drug delivery system (TDDS) adhesion as a critical safety, efficacy and quality attribute.

Transdermal drug delivery systems (TDDS), also known as "patches," are dosage forms designed to deliver a therapeutically effective amount of drug across a patient's skin. The adhesive of the transdermal drug delivery system is critical to the safety, efficacy and quality of the product. In the Drug Quality Reporting System (DQRS), the United States Food and Drug Administration (FDA) has received numerous reports of "adhesion lacking" for transdermal drug delivery systems. This article provides an overview of types of transdermals, their anatomy, the role of adhesion, the possible adhesion failure modes and how adhesion can be measured. Excerpts from FDA reports on the lack of adhesion of transdermal system products are presented. Pros and cons of in vitro techniques, such as peel adhesion, tack and shear strength, in vivo techniques used to evaluate adhesive properties are discussed. To see a decrease in "adhesion lacking" reports, adhesion needs to become an important design parameter and suitable methods need to be available to assess quality and in vivo performance. This article provides a framework for further discussion and scientific work to improve transdermal adhesive performance.     

Corneoscleral transplantation in congenital corneal staphyloma and Peters' anomaly

An infant born with bilateral corneal clouding diagnosed clinically as congenital anterior staphyloma and Peters' anomaly was confirmed histopathologically. This case report demonstrates one clinical spectrum of Peters' anomaly. The clinical course and histopathologic findings are detailed as is a unique surgical approach of corneoscleral graft used to perserve the right globe.