Science topic

Skin Absorption - Science topic

Uptake of substances through the skin.
Questions related to Skin Absorption
  • asked a question related to Skin Absorption
Question
3 answers
I am looking for a plain/empty gel system, which we can directly buy and load the drug for the purpose of transdermal delivery. Your kind help will be appreciated.
Relevant answer
Answer
You can try customized molds to fabricate hydrogel microneedles for transdermal drug delivery.Many hydrogels are commercially available.
  • asked a question related to Skin Absorption
Question
6 answers
Every time i working with hyaluronic acid I got some bubbles inside gel. It desn't matter in lab and do not affect on the acid. Few days ago I saw syringe (with a needle) with clear hyaluronic acid without any bubbles. Friend send me a photo of bottle with the product without bubbles too. How do they made it??? I was trying vacuum suction but did not get proper effect.
Relevant answer
Answer
Problem solved. Thanks to all!
  • asked a question related to Skin Absorption
Question
3 answers
We want to calculate the topical dose of a peptide drug which isn't used on wounded skin before but we have the systemic i.p dose
Relevant answer
Answer
For a new molecule, it is interesting to see first, a mathematical modeling for example with the equation of Pott and Guy (there are others but which do not provide more information) All the mathematical models are absolutely false, but they first allow us to verify whether the molecule has the potential to cross the skin barrier or if it is very limited. If your drug has a log P between 1 and 4 and a MW of less than 500, the amount absorbed may be sufficient. A peptide of high molecular weight will not cross the skin barrier, or so weakly that it will be of no benefit. You already have an idea if the molecule will be able to cross the barrier (the melting point, if it is a salified form, the formulation are other factors to take into consideration) If your molecule has a potential absorption, you can test in 2nd on "franz cells" human or porcine skin, otherwise it is a waste of time.
  • asked a question related to Skin Absorption
Question
3 answers
Per- and polyfluoroalkyl substances (PFASs)are a ubiquitous group of environmental chemicals that cause numerous detrimental impacts on the environment and human health. According to performed studies, these metabolically inert chemicals enter the body of humans and animals and transfer into target tissues such as liver, kidney, bone, skin, etc. with the help of protein carriers in the bloodstream. From a dermatological point of view, what toxic consequences are most likely to occur in response to the dermal bioaccumulation of environmental contaminants such as PFASs? What are the differences between possible toxic effects caused by internal dermal exposure (dermal bioaccumulation) to a chemical and external dermal exposure (dermal absorption) to the same chemical?
Thanks in advance.
Relevant answer
Answer
Internal dermal exposure from your query appears to be chronic toxin accumulation of different toxicant posing as health risk. Case examples are emerging chemicals and heavy metals. They follow the processes of bio-accumulation, through bio-concentration and bio-accumulation leading to undue dermal irritations and severe ailments. External dermal exposures on the other hand could refer to the conditions where the skin is exposed to harsh U-V radiations without protecting its delicate nature with the resultant non-melanoma skin cancer.
  • asked a question related to Skin Absorption
Question
2 answers
If I want a certain antioxidant in a formulation to be penetrated into the skin , Is it ok to load it into ethosomes or the loading means that the whole package will be delivered ?
Relevant answer
Answer
Ethosomes will penetrate to a certain extent due to their improved elasticity as per compared to normal lipisomes that are more rigid, which allows a certain deformation of vesicles to trepass the epidermis.
  • asked a question related to Skin Absorption
Question
8 answers
I'm interested in hearing from the experts in pharmacology/drug delivery: in transdermal drug delivery, which drug parameters are most important in determining the rate of removal from the skin via uptake by cutaneous vasculature? For example: lipophilic, small MW and unchanged compounds enter the stratum corneum with greatest ease. In the same vein, what is the relationship between an individual drug's physicochemical properties and its absorption/removal to local skin circulation.
Relevant answer
Answer
Hi.
This is a difficult question, as you can see form the lack of definitive (or not so definitive) literature. In fact it is still an important area of research in this and other topic areas. Still, I can talk in some generalities, but it is likely that each drug will be its own case or possibly exception.
The problem arises, at least in part, because there are competing physicochemical factors involved, which affect the interaction of a drug with both the skin/physiology and the dosage form. For instance, a lipophilic molecule will more easily partition into the stratum corneum (which dominates the surface area of the skin) while a more hydrophilic molecule will enter more easily through pores (which represent only a fraction of a percent typically of the skin area). Based on that, lipophilic molecules would appear to have an advantage for delivery. However, the molecular mobilities through pores are likely to be far higher than through the stratum corneum, which favors hydrophilic drugs (at least on a per area basis).
Another consideration is that lipophilic drugs are more likely to depot in the stratum corneum and the skin on the whole. On the other hand, those drugs may have sufficiently low solubility to hinder partitioning into the aqueous media below the stratum corenum, which is needed to enter the blood and be carried away to the general circulation. (This may be a consideration when thinking about transdermal delivery vs. topical delivery, for instance.)
Even before that, there is the question of the interaction between a drug and the dosage form. If creams or ointments are applied, the distribution of the drug in the dosage form before application is important. For instance, distribution into the aqueous vs. oil for creams and emulsions, or in the oily phase for ointments, etc. will affect how the dosage form gives up or delivers the drug to the skin. Equally important is how the topical dosage form interacts with the skin, which will affect the delivery and partitioning of the drug as a function of both the dosage form and the skin.
All of this is still poorly understood. The FDA is interested in this problem, as evidenced by funded studies on bioequivalence for topical dosage forms based on physical characterization of the dosage form and not primarily from in vitro transdermal studies. (For instance, RFA-FD-18-010 - Bioequivalence of Topical Products: Elucidating the Thermodynamic and Functional Characteristics of Compositionally Different Topical Formulations form 2018).
I apologize for going on and on, but I think you can see this is a difficult area. It seems surprising that we don't have a much better understanding given that we understand the basic principles that may apply. On the other hand, it is not surprising at all given the many complex interactions, all with different effects in kind and magnitudes.
My own view is that some experimental techniques plus individualized models may be the answer... the problem is that each drug and dosage form becomes its own study, and we don't seem to have a standardized suite of studies yet to apply to the problem on a drug-by-drug and formulation-by-formulation basis.
Hopefully, this is of interest and sheds some light on the challenges ahead.
Thanks!
Bob
  • asked a question related to Skin Absorption
Question
7 answers
Onr of my patient reported that several workers in factory are suffering from diabetes and it might be due to absorption of sugar through inhalation or skin absorption.
Relevant answer
Answer
Hi Satish, sugar is not absorbed through intact skin. No way.
Inhalation of sugar? I have no clue.
I agree with Sikander that this could just be hearsay. But you should make a note of it anyway.
  • asked a question related to Skin Absorption
Question
3 answers
I know how to calculate how much time you can spend in the Sun before starting to burn, or which SPF you should choose according the UV Index for the day and your Skin Type and if you are using SPF, etc. There is several formulas to know it. But I don´t find when you can return to be sun exposure if you have if you've already spent this time
For example: A person with Skin Type 3 at sea level exposed to a UV Index of 10 would start to suffer from sunburn after 30 minutes.  My question is If he have already spend this 30 min. When this person can return to be sun exposed? The following day? and Why?
 Thanks
Relevant answer
Answer
Hello,
As I understand, the optimal strategy of outdoor behavior is not to get erythema, but get a small UV radiation dose (less than minimal erythemal dose) every day for necessary vitamin D formation.
  • asked a question related to Skin Absorption
Question
1 answer
Ksenia Bystrova speculated in 2009 that c-tactile fibers might be stimulated by amniotic fluid via lanugo hair. If this were accurate, the potential involvement of c-tactile fibers in hydrotherapy might deserve a closer look – warm currents have a lot in common with gentle stroking, which is the main modality c-tactile fibers respond to.
Relevant answer
Answer
Dear Dr Schittter, I happen to lead a course on aquatic therapy in the Kliniken Valens and discussed the question with a colleague. You might want to contact Dr Daisuke sat in Japan and also my colleague who is here with me now: Ben Waller from Jyvaskyla university in Finland (ben.waller@jyu.fi). Kind regards, Johan Lambeck, Geneva
  • asked a question related to Skin Absorption
Question
8 answers
How to create and analyze cubical tissue model, and  What is meaning of SAR 10g ?
Relevant answer
Answer
To begin working with SAR, you should decide which model or phantom is applicable to you. There are homogeneous and inhomogeneous phantoms. The first can be represented with cubes, spheres or any form as long as it consists of the properties of one tissue (you can refer to FCC official website to obtain those properties) . You can simply design it using CAD software such as CST MWS. The latter is known as voxel phantoms, where mimicking the tissues of the living body is close to reality. The inhomogeneous phantoms are very complex and you can only import their data from libraries of your selected simulator, however that will require you a special licence and a powerful computer. Then you can calculate SAR over 10g or 1g, provided that you have already obtained the power loss. Results from homogeneous and inhomogeneous model will vary slightly depending on the closeness of their density. 
I hope this gives you an idea how to start 
  • asked a question related to Skin Absorption
Question
1 answer
I want to know further about this in order to understand further why the veins are blue when the baby get the cyanosis?
We know that, skin get its color by the subtractive mechanism of color mixture. And in the dermis there are many substance for instant, protein, hemoglobin, melanin etc that removed color and I think it is kind of a transfer function.
What is the relationship between transfer function, H(f) with molar extinction of oxyhemoglobin & deoxyhemoglobin? So far, we know that a control system of H(f) is = 1/s-1, 1/s.
Can i  assume that the transfer function of the skin chromophores (skin tissue, fat, melanin etc)  = 1 / molar extinction of oxyhemoglobin/ deoxyhemoglobin?
Or can I assume that a transfer function of hemoglobin = molar extinction coefficient itself?
If so, can you suggest any papers or articles that related with this.
Thank you.  
Relevant answer
Answer
The answer is a bit complicated. The skin and other tissues are light absorbers and scatterers. I would suggest you reading the following papers (by doi):
- DOI 10.1007/s10812-012-9612-4
- DOI 10.1134/S0030400X14090161
The model of light interaction with human tissues is discussed there, so you may get close to the solution of your problem.
  • asked a question related to Skin Absorption
Question
3 answers
Is there any method to reduce the absorption or penetration of a drug in topical formulation since the action is sought only on the surface of the skin and not beneath the skin? Your input helps me a lot.
Thanks in advance. 
Relevant answer
Answer
@Hiep Nguyen: It is for removing Keratolytic treatment to remove warts and other lesions in which the epidermis produces excess skin. It needs to soften keratin (outer layer of human skin), a major component of the skin. Since the drug is an acid if it penetrates deep into the skin it leads to severe irritation. 
  • asked a question related to Skin Absorption
Question
5 answers
Cell sheet attachment in the skin during transplantation.
Relevant answer
Answer
I don't really understand the question.  What are you trying to do?  If you want low adhesion in a biological system how about a fibrin sealant.
Robin
  • asked a question related to Skin Absorption
Question
3 answers
When we select any drug for topical use, first we talk about the skin partition coefficient of that drug. How can we determine the skin partition coefficient of any drug selected for topical use?
I think it also depends on the drug delivery system. i.e. if we are talking about transdermal patches, then during selection of drug it is required, but in case of elastic vesicles, skin partition coefficient is not a mandatory parameter.
Are the experienced researchers in such a type of investigation agreeing with me?
Relevant answer
Answer
Thanks Monica for reply