Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Urea Cycle01:23

Urea Cycle

The urea cycle describes how liver cells convert ammonia to urea. Ammonia is a toxic waste product of protein catabolism. Land animals must convert ammonia into the less toxic urea which can be safely eliminated by the kidneys through urine. Marine animals excrete ammonia directly, and the surrounding water dilutes the ammonia to safe levels.
Non-Oral Extravascular Drug Absorption Routes01:15

Non-Oral Extravascular Drug Absorption Routes

Non-oral extravascular routes, which encompass sublingual, buccal, topical, intramuscular, and inhalation methods, primarily utilize passive diffusion to transport drugs into the systemic circulation. The absorption rates and effectiveness of these routes depend on the drug's physicochemical properties, as well as the patient's anatomical and pathophysiological state.
Lipophilic drugs that are stable at salivary pH (6) and exhibit minimal binding to the oral mucosa are absorbed more effectively...
Drug Elimination by Renal Route: Tubular Secretion01:15

Drug Elimination by Renal Route: Tubular Secretion

Once the process of glomerular filtration is completed, blood carrying unfiltered drug molecules traverses through efferent arterioles and makes its way into the peritubular capillaries in the proximal tubule. A variety of carriers play a pivotal role in actively secreting drugs from these peritubular capillaries into the tubular fluid. The organic anion transporter transfers acidic drugs, against an electrochemical gradient, from the peritubular capillaries into the renal tubule cells and...
Drug Elimination by Renal Route: Tubular Reabsorption01:22

Drug Elimination by Renal Route: Tubular Reabsorption

During the process of renal excretion, as the glomerular filtrate progresses to the distal convoluted tubule (DCT), drugs that are highly permeable, lipophilic, and nonionized undergo passive reabsorption from the tubular fluid into the surrounding peritubular capillaries. This reabsorption process restricts their elimination through the kidneys. However, the majority of drugs are either weak acids or weak bases, and their ionization level is dependent on pH. By altering the pH of urine, the...
Pore Transport and Ion-Pair Transport01:17

Pore Transport and Ion-Pair Transport

Pore transport and ion-pair formation are critical mechanisms for the absorption and distribution of drugs in the body.
Pore transport, also known as convective transport, is a process where small molecules like urea, water, and sugars rapidly cross cell membranes as though there were channels or pores in the membrane. Although direct microscopic evidence is limited  but the concept of pores or channels is widely accepted based on physiological evidence. Despite the lack of direct microscopic...
Drug Excretion: Miscellaneous Routes01:10

Drug Excretion: Miscellaneous Routes

Drug excretion involves various organs, including the liver, intestines, skin, and eyes. In the case of drugs or toxins, they can be actively secreted into bile by transporters in the hepatocyte's canalicular membrane. These substances enter the GI tract during digestion and may be reabsorbed into the body from the intestine. This process, known as enterohepatic recycling, can significantly prolong the presence and effects of a substance in the body. To interrupt this cycle, specific substances...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Self-reported financial difficulties of colorectal cancer patients 1 year after start of treatment.

ESMO open·2025
Same author

Computed tomography chest imaging for the detection of pulmonary hypertension in patients with post-tuberculosis lung disease.

African journal of thoracic and critical care medicine·2025
Same author

Lack of evidence for HEV infection in Baltic sea mussels (Mytilidae).

BMC infectious diseases·2025
Same author

Increased frequency of TIGIT<sup>+</sup>CD73-CD8<sup>+</sup> T cells with a TOX<sup>+</sup> TCF-1low profile in patients with newly diagnosed and relapsed AML.

Oncoimmunology·2021
Same author

First-line immune checkpoint inhibitors for extensive stage small-cell lung cancer: clinical developments and future directions.

ESMO open·2021
Same author

Early Antiretroviral Therapy in HIV-Infected Children Is Associated with Diffuse White Matter Structural Abnormality and Corpus Callosum Sparing.

AJNR. American journal of neuroradiology·2016

Related Experiment Video

Updated: Jun 23, 2026

An All-Human Hepatic Culture System for Drug Development Applications
07:23

An All-Human Hepatic Culture System for Drug Development Applications

Published on: October 20, 2023

Percutaneous absorption of urea.

C Ackermann1, G L Flynn, C J Wyk

  • 1Department of Pharmaceutics, Potchefstroom University for Christian Higher Education, Potchefstroom, 2520, South Africa.

International Journal of Cosmetic Science
|May 23, 2009
PubMed
Summary

The in vitro skin permeation of urea increases over time due to water altering the stratum corneum, creating hydrophilic channels. This phenomenon facilitates the passage of polar substances like urea through the skin.

More Related Videos

In Vivo Luminal Measurement of Distension-Evoked Urothelial ATP Release in Rodents
09:17

In Vivo Luminal Measurement of Distension-Evoked Urothelial ATP Release in Rodents

Published on: September 7, 2022

Related Experiment Videos

Last Updated: Jun 23, 2026

An All-Human Hepatic Culture System for Drug Development Applications
07:23

An All-Human Hepatic Culture System for Drug Development Applications

Published on: October 20, 2023

In Vivo Luminal Measurement of Distension-Evoked Urothelial ATP Release in Rodents
09:17

In Vivo Luminal Measurement of Distension-Evoked Urothelial ATP Release in Rodents

Published on: September 7, 2022

Area of Science:

  • Dermatology
  • Pharmacokinetics
  • Materials Science

Background:

  • Understanding skin barrier function is crucial for drug delivery.
  • Previous studies indicated an increasing permeability phenomenon with hydrophilic compounds.
  • The precise mechanisms behind altered skin permeability required further investigation.

Purpose of the Study:

  • To investigate variables affecting in vitro urea permeation through hairless mouse skin.
  • To elucidate the causes of the observed increasing permeability phenomenon.
  • To characterize the time-dependent changes in skin permeability.

Main Methods:

  • In vitro permeation studies using hairless mouse skin.
  • Varied urea concentrations (0.01 M to 1.67 M) and buffer systems (including saline, (N-morpholine)propanesulphonic acid, and tris(hydroxyme)amino-methane).
  • Assessed permeation of urea, tritiated water, methanol, and water.

Main Results:

  • Urea permeation increased for approximately 100 hours, followed by a 25-hour steady state.
  • Urea concentration did not influence its own permeation rate within the tested range.
  • Methanol and water showed similar increasing permeation patterns; tritiated water permeation was unaffected by urea.

Conclusions:

  • Water penetration and association with stratum corneum components likely alter skin ultrastructure.
  • This alteration is hypothesized to create hydrophilic diffusion channels, enhancing polar substance permeation.
  • The underlying microscopic physical events driving these ultrastructural changes warrant further research.