Skin therapeutics Flashcards
Types of chemical penetration enhancers
Lipid disruption-PE disrupts S/C lipid organisation
Protein modification-Interact with keratin opening up the dense protein structure making it more permeable
Partitioning promotion-solvent enters S/C changing its solubility properties
how can volatile systems enhance drug delivery into the skin
Volatile systems, such as gels and foams, contain ingredients that evaporate quickly, leaving behind a concentrated layer of drug on the skin’s surface. This concentrated layer of drug can then dissolve into the skin’s lipids, allowing it to penetrate more deeply into the skin.
Types of permeation enhancers
permeation enhancers include fatty acids, such as oleic acid and linoleic acid, which can also disrupt the lipid structure of the stratum corneum, and terpenes, such as limonene and menthol, which can create temporary pathways through the skin’s barrier layer.
However they can cause irritation and toxicity
how can manipulating the drugs chemical properties enhance drug delivery into the skin
Changing the molecular weight: Drugs with higher molecular weights tend to penetrate the skin less effectively than those with lower molecular weights. By reducing the molecular weight of a drug, it can become more easily absorbed into the skin.
Modifying the polarity: The skin has a hydrophobic barrier that prevents the penetration of hydrophilic molecules. By modifying the polarity of a drug to make it more lipophilic, it can more easily penetrate the skin.
Adjusting the pH: The skin’s pH is typically slightly acidic, which can limit the absorption of some drugs. By adjusting the pH of a drug to match the skin’s pH, it can more easily penetrate the skin.
Encapsulating the drug: Encapsulating the drug within a lipid or polymer can protect it from degradation and increase its solubility, allowing it to more easily penetrate the skin.
how can colloids can enhance drug delivery into the skin
Liposomes: Liposomes are colloidal particles composed of a lipid bilayer that can encapsulate hydrophilic and hydrophobic drugs. Liposomes can penetrate the skin more effectively due to their small size and lipid nature. They can also protect the drug from degradation and enhance its solubility.
Microemulsions: Microemulsions are colloidal systems that contain water, oil, surfactant, and co-surfactant. They are thermodynamically stable and have a small droplet size that can enhance drug delivery to the skin. They can also increase the solubility of drugs and enhance their penetration into the skin.
Dendrimers: Dendrimers are highly branched, monodisperse polymers that can be used to deliver drugs to the skin. They have a high surface area and can be functionalized with specific ligands to enhance their targeting to skin cells. They can also protect the drug from degradation and enhance its solubility.
how can different device technologies can improve the delivery of drug across the skin
Iontophoresis: Iontophoresis is a non-invasive method of drug delivery that uses a small electric current to enhance the transport of charged drug molecules across the skin. This technology is particularly useful for drugs that are poorly absorbed through the skin or have low bioavailability. Iontophoresis can also be used to deliver large molecular weight drugs, such as proteins and peptides, across the skin.
Sonophoresis: Sonophoresis is a technique that uses low-frequency ultrasound waves to enhance the delivery of drugs across the skin. The ultrasound waves create small cavities or pores in the skin, allowing the drug to penetrate deeper and faster than it would through passive diffusion. Sonophoresis is particularly useful for drugs that have a low permeability coefficient, as well as for drugs that need to be delivered to deeper tissues.
Microneedles: Microneedles are small, painless needles that are used to puncture the skin and create channels for drug delivery. Microneedles can be made from various materials, such as metal, polymer, or silicon, and can be designed to be dissolvable or non-dissolvable. Dissolvable microneedles are particularly useful for delivering vaccines and other therapeutic agents that require a single dose.
Electroporation: Electroporation is a technique that uses an electrical field to create temporary pores in the skin, allowing drugs to penetrate more deeply and rapidly than they would through passive diffusion.
Thermal ablation: Thermal ablation is a technique that uses heat to remove a small section of the skin, allowing drugs to be delivered directly to the underlying tissue. This technique is particularly useful for delivering drugs to the dermis or hypodermis, where most of the skin’s blood supply is located.
What are the limitations of trying to use complex devices to try and improve transdermal drug delivery
Complexity: Complex devices often require specialized training and expertise to use, and may be difficult for patients to use at home. This can limit the accessibility of the therapy, and increase the risk of errors or adverse events.
Cost: Complex devices can be expensive to develop and manufacture, which can increase the cost of therapy for patients. This may limit the availability of the therapy, particularly in low-income populations.
Safety concerns: Some complex devices, such as those that use electroporation or thermal ablation, can cause pain or discomfort, and may increase the risk of infection or tissue damage. The safety of these devices needs to be carefully evaluated and monitored.
Patient adherence: Even if a complex device is effective at improving drug delivery, patient adherence to the treatment regimen is still a critical factor for successful therapy. Patients may be reluctant to use a complex device or may find it difficult to incorporate into their daily routine, which can limit the efficacy of the therapy.
Regulatory hurdles: Complex device technologies may require regulatory approval, which can add to the time and cost of bringing a therapy to market. This can also limit the availability of the therapy, particularly in countries with limited regulatory infrastructure.
Name 5 factors than can influence the process of passive transport of a molecule into the skin. (5 marks)
Molecular size: The size of the molecule can affect its ability to passively diffuse across the skin. Smaller molecules are generally able to diffuse more readily than larger molecules.
Lipophilicity: The lipid solubility of a molecule can also affect its ability to passively diffuse across the skin. Highly lipophilic molecules are generally able to diffuse more readily than hydrophilic molecules.
Concentration gradient: The concentration gradient of a molecule between the outside and inside of the skin can affect its passive transport. A higher concentration gradient generally results in more rapid passive diffusion.
Skin integrity: The integrity of the skin barrier can also affect passive transport. Damaged or compromised skin may allow for more rapid passive diffusion of molecules.
pH of the environment: The pH of the skin can affect the charge of the molecule, which can in turn affect its ability to passively diffuse across the skin. Molecules that are charged may have reduced ability to diffuse across the skin.
