Author: Dr. Saeed Qureshi, Ph.D.

It is requiring drug dissolution testers, which do not (and cannot) determine dissolution characteristics of any product (tablet and capsule in particular). The amazing fact is that these are the only ones mostly recommended and accepted by the authorities, even sometimes as a substitute for clinical (bioequivalence) assessments. Why? How does it make sense – scientific or otherwise?

Some links for further details:
(1) Note that no one can determine, or has determined, dissolution characteristics of any product using the currently suggested apparatuses and/or methods. It has all been an illusion! (link)
(2) Bio-waivers! (link)
(3) Pharmacopeial Dissolution Testers (link)

A couple of days ago, I read two recent articles, one from the US FDA [1] and the other from the USP, defending and rationalizing regulatory and pharmacopeial practices and standards for assessing pharmaceutical products. These reports appear to respond to the concerns often expressed regarding deficiencies in regulatory product evaluations. This article provides an alternate view of the issues and suggests a solution for the authorities’ consideration. For the complete article, please follow the link (http://www.drug-dissolution-testing.com/?p=3198).

In the report from the US FDA, the emphasis is on justifying the current regulatory practices for adequately evaluating manufacturers or product manufacturing. It is claimed that the US FDA uses rigorous risk-based approaches in monitoring the plants (i.e., inspections) and evaluating pre-manufacturing submissions (i.e., NDA, ANDA). However, such claims may not be new, and the concerns persist, perhaps with increasing frequency and intensity. These concerns are due to mixing and confusing the two, i.e., manufacturing (or its quality) and the quality of the manufactured products. Authorities miss the difference and consider them the same thing. This misunderstanding confuses and is the root cause of the issues and concerns.

Public or patients need or require quality products, while the regulatory authorities have to ensure such. Unfortunately, there is no commonly accepted or official definition of a quality product; thus neither patient would get quality products, nor authorities can provide assurance. Authorities assume that if manufacturers meet the suggested regulatory processes and/or specifications (i.e., in compliance), then somehow the products manufactured would become of quality. On the other hand, if deviations from the processes and/or specifications are observed or perceived (which are often subjective), then the manufacturers would be labeled as non-compliant, and by extension, product quality is considered to be as substandard (or “adulterated”). Under the current regulatory system/requirements, it is really impossible to establish the quality of the products and their link to manufacturing.

It is important to note that, at present, product quality and manufacturing are based on in vivo (bioequivalence) and in vitro (drug dissolution) assessments. These techniques, as recommended by the authorities, are in fact scientifically in-valid and non-GMP compliant [3, 4]. It is, therefore, essential to recognize that regulatory assessments provide no scientifically valid support for establishing or monitoring the product quality, or lack of it, pre- or post-approval. Unfortunately, the manufacturers have been to bear the faults when guidance documents, standards, and specifications require attention and reconsideration.

The USP article rationalizes the approach of conducting performance of the dissolution testers used and required for establishing the quality of the products. This performance test is based on an arbitrarily selected product (which has no link to human use as a product) to establish validation of testers for the products for human use. In reality, claims made by the USP are scientifically invalid and simply false. USP promotes the use of these testers and tests for establishing the quality of products for human use, while these have never been tested or validated using any drug product for human use. If a company had made such a claim, it would have been disqualified and put out of business immediately (e.g., Theranos case [5]). However, USP and the US FDA promote these testers/tests for the quality assessment of the products. These apparatuses have clearly been shown to provide highly variable, unpredictable, and irrelevant dissolution results [6]. So much so that no one can determine appropriate and accurate dissolution characteristics of any product using USP apparatuses [7]. Therefore, authorities have to reconsider the use and requirements of the tests and testers.

To address the concerns and adequately assess product quality, authorities must define “product quality” with a measurable parameter and implement its use with scientifically qualified and validated tests and testers. Some suggestions in this regard are provided here [8] 

[1] Statement from FDA Commissioner Scott Gottlieb, M.D., and Director of FDA’s Center for Drug Evaluation and Research Janet Woodcock, M.D., on the FDA’s continuing efforts to maintain its strong oversight of generic drug quality issues domestically and abroad (Link).

[2] The Critical Role of the USP Performance Verification Test in Dissolution Testing and Qualification of the Paddle Apparatus (Link]

[3] Time to rescind the regulatory requirements of bioequivalence evaluations and the current pharmacopeial drug dissolution practices as these do not provide quality assessment of pharmaceutical products (http://www.drug-dissolution-testing.com/?p=3065)

[4] “Regulatory (pharmaceutical) science” – lacks logic as well as science! (Link)

[5] Theranos (Link)

[6] Variability and unpredictability, everywhere! (Link)

[7] Note that no one can determine, or has determined, dissolution characteristics of any product using the currently suggested apparatuses and/or methods. It has all been an illusion! (http://www.drug-dissolution-testing.com/?p=1957]

[8] Seeking Metrics to Define Drug Quality (Link)

[9] Product Quality Metric (do not confuse it with drug/medicine quality) (Link).

[10] Universal Dissolution Test/Tester (Link)

In general, to apply a risk-based approach to establish the quality of anything, one would require a defined and measurable outcome/parameter. Once such an outcome/parameter is known or established, then it is used to reflect the chances of achieving success or failure in manufacturing or producing quality products. If the defined outcome/parameter is not available, then it would not be possible to use a risk-based approach. The manufacturing of quality pharmaceutical products falls in this category, i.e., there is no define parameter/outcome available for a “quality product,” thus risk-based assessment approach in pharmaceutical manufacturing is not possible at present.
To apply a risk-based approach, one would require to define the quality pharmaceutical products with a measurable parameter. So, please seek a definition of a “quality pharmaceutical product” along with its measurable parameters using qualified and validated scientific methods. As an example, please see here (Link).

Hopefully, the year in which “quality pharmaceutical products” will be defined along with their measurable standards/specifications so that manufacturers worldwide can manufacture such products efficiently and economically. Please follow the link for more details (1, 2).

In the life cycle of drug product development, several types of biorelevant dissolution data are generated (single stage, 2-stage, ASD, etc.) to aid formulation development. These dissolution data are also used in PBPK models.

What type of in vitro biorelevant dissolution methods do you use as input in PBPK modeling?

Can there be a general decision tree on the use of types of biorelevant dissolution data in PBPK models for applications in formulation selection?

That is a very good question!
In this respect, one should ensure that the apparatus/method used for dissolution testing should be validated first. It is important to note that, at present, none of the apparatuses/methods have been validated. For validation purposes, the apparatuses/methods are to be validated independently using a reference product with known dissolution characteristics, which should be applied to the test products. Scientifically validation cannot be achieved using products under development (Link).

A product can only be considered of quality and, by extension, safe and effective if it meets specification(s) directly linked to a defined quality property/parameter. Currently, a quality parameter for pharmaceutical products, such as tablets and capsules, is undefined; thus, making valid claims in this regard is impossible.

Current regulatory and pharmacopeial-approved products available on the market should only be considered compliant to arbitrary standards/specifications, mostly invalid and irrelevant for quality. Claims are unsupported – a similar scenario as observed in the case of Theranos (link). Please use caution when making or accepting such claims, and seek appropriate help addressing the issue (link).

Please consider defining a quality product along with its measurable parameter, which will make most of the current regulatory requirements and practices unnecessary, resulting in efficient manufacturing and significant cost reductions. Please follow the links for further details (1, 2)

One cannot establish the quality of anything without knowing or defining it first. This is simple logic!
However, regulatory authorities, including pharmacopeias, have been trying to prove this logic wrong! That is, they have been making claims of establishing and monitoring the quality of pharmaceutical products such as tablets and capsules – without knowing or defining it. They will fail and have failed!
Logically and/or scientifically, none of the products (approved or otherwise) available on the market can be considered quality. Guidance and compliance-based system, along with the plant inspections, is a thick smoke screen hiding the reality and hindering progress.

Please, define a quality product and set the standards and specifications accordingly so that appropriate quality products can be manufactured and monitored. For further detail, please see here.

Considering solubility characteristics of a drug in the stomach (i.e., pH range of 1 to 3) are pretty much useless from a drug’s absorption perspective. Even if a drug gets dissolved in the stomach, it will be precipitated out in the intestine if it has lower solubility at a higher pH.

For absorption purposes, a drug must dissolve, not necessarily completely but in some quantity, in the intestine where pH ranges from 4.5 to 7. Drugs get absorbed in steps in the intestine by a continuous extraction process; thus, the complete dissolution of drugs at any given time (so-called “sink condition”) is unnecessary.

Moreover, dissolution characteristics are not usually determined for a drug – dissolution tests are conducted to evaluate products. The choice of medium is linked to the physiological environment of the GI tract, not to the drugs or products. Please pay attention to the principles of science and the laws of nature. For further detail, please follow the link (link).

Dear experts:

In the area of simulation and modeling, including developers of commercial software, note that I may not be able to argue with you regarding your methodologies of data analysis, modeling and/or simulation aspects as this is not my area of expertise. However, I know with certainty that you would require valid and accurate data for your analysis purposes. The difficulty is that you would not have access to such valid and accurate data, at least for evaluating tablet or capsule products for predicting plasma drug levels or profiles.  The in vitro drug dissolution results represent or simulate in vivo dissolution and, by extension, plasma drug levels or profiles.

You would require such data to validate your simulation or modeling outcome at least for the product development and manufacturing stages. Unfortunately, no one, at present, is generating or can generate valid in vitro dissolution data. Thus, your efforts of conducting simulation/modeling are regrettably of no use and would not help the industry, regulatory authorities, or anyone else. Please, do not make claims about the successes and usefulness of such exercises.

One of the main reasons for not being able to obtain valid in vitro dissolution or drug release data is that the recommended and required (e.g., from USP and FDA) dissolution testers for such purposes have never been shown to provide valid and accurate dissolution results. These testers have never been validated for their intended use or purpose. Vendors/manufacturers make extraordinary efforts and take pride in providing “compliant” testers, i.e., meeting or exceeding “physical or fixed” specifications according to the pharmacopeial (such as USP) requirements; however, they are unable to validate the testers as dissolution testers. For example, no present vendor can provide valid in vitro dissolution results if given a blinded sample of a tablet/capsule product. Therefore, in this respect, claims made by the vendors are also not accurate that they are selling or manufacturing dissolution testers. At best, the only claim they can, or should, make is that they are selling simple stirrers. Perhaps more disturbing is that these stirrers, when used as required for dissolution evaluations, cannot provide valid and accurate dissolution results, which are documented extensively in the literature because of their design and operation limitations and flaws.

In short, please use and promote the simulation and modeling techniques with care and certainly use extra caution in making claims about future expectations and successes.