Delivery of CNS drugs Flashcards
What is Lipinski’s Rule of 5?
A set of criteria to evaluate druglikeness based on molecular properties:
* Hydrogen bond donors ≤ 5
* Hydrogen bond acceptors ≤ 10
* Log P ≤ 5
* Molecular weight ≤ 500 Daltons (≤ 300 Da for hydrophilic molecules, ≤ 1kDa for lipophilic molecules)
* Must be unionised.
Lipinski’s Rule helps predict the absorption and permeation of drugs.
What is the maximum volume for intranasal delivery?
Max 200 uL.
This volume is crucial for effective drug absorption in the nasal cavity.
What is the pH range for intranasal delivery?
pH 4 – 7.4.
This range helps ensure drug stability and absorption.
What does the term ‘tonicity’ refer to in intranasal delivery?
Tonicity range is 300 – 700 mOsmol.
Proper tonicity is important to prevent irritation of the nasal mucosa.
What device feature is crucial for intranasal drug delivery?
A nozzle that bypasses the nasal vestibule (hair).
This helps in delivering the drug more effectively to the nasal cavity.
What is Spray Content Uniformity (SCU)?
The amount of drug delivered per pump.
SCU is important for ensuring consistent dosing.
Name one thermoreversible gel excipient used in drug formulation.
Pluronic F127.
It can be combined with other materials like Chitosan or HPMC.
Other thermoreversible gels are Poloxamer 407 and 188
What is the main way for drugs to cross the skin in transdermal delivery?
Via intercellular lipidic domains.
This pathway is critical for effective transdermal absorption.
What is a common antioxidant used in drug formulations?
DL-alpha-tocopherol. (a synthetic form of Vit E)
It is often used to stabilize formulations.
What is the maximum molecular weight for a drug to be considered suitable for intranasal delivery?
≤ 450 Da.
Less than the 500 Da for gut abdorption. This ensures better absorption rates in the CNS.
Fill in the blank: The maximum Log P for a drug according to Lipinski’s Rule is _______.
≤ 5.
A higher Log P indicates increased lipophilicity.
What type of polymer is used in transdermal delivery systems?
Co-polymer membrane - Ethylene-vinyl acetate copolymer.
This material helps control drug release rates.
Name a key consideration for the delivery device in intranasal drug delivery.
Reproducibility of pump spray weight.
Consistent delivery is essential for therapeutic effectiveness.
What is the function of sodium acetate, citrate, and phosphates in injections?
Buffer
These components help maintain pH stability in the formulation.
What is the typical concentration of benzyl alcohol used as a preservative?
1-2% w/v
Benzyl alcohol is commonly used to prevent microbial growth.
What is the function of chlorbutanol in injections?
Preservative
Chlorbutanol helps to extend the shelf life of the product.
What concentration range is typical for methylparaben as a preservative?
0.1 – 0.18
Methylparaben is part of a group of preservatives known as parabens.
What is the primary function of propylparaben?
Preservative
Propylparaben is used to prevent the growth of mold and bacteria.
What concentration of phenol is typically used as a preservative?
0.2 – 0.5
Phenol is effective against bacteria and fungi.
What is the function of thiomersal in injections?
Preservative
Thiomersal is used to prevent bacterial contamination.
What is mannitol classified as in injections?
Tonicity adjusting agent / cryoprotectant
Mannitol helps to stabilize the formulation during freeze-drying.
What is the typical concentration of sodium chloride used as a tonicity adjusting agent?
0.9% w/v
Sodium chloride helps to match the osmolarity of body fluids.
What is the function of ethanol in injections?
Solvent
Ethanol is used to dissolve other ingredients in the formulation.
What are glycerin/glycerol used for in injections?
Solvent/tonicity adjustment
Glycerin can also provide moisture to the formulation.
What is glycine’s role in injections?
Solvent/tonicity adjustment
Glycine can help maintain the osmotic balance of the solution.
What is PEG’s role in injections?
Solvent
PEG is used to improve the solubility of poorly soluble compounds.
What is the function of propylene glycol in injections?
Solvent
Propylene glycol is often used for its ability to dissolve many compounds.
What is the function of polysorbate 20 & 80 in injections?
Surfactant
These surfactants help to reduce surface tension and improve the stability of emulsions.
What is the role of cyclodextrin in transdermal delivery?
Permeation enhancer
Cyclodextrin can improve the absorption of drugs through the skin.
What is glyceryl monooleate used for in transdermal delivery?
Permeation enhancer, bioadhesive, sustained release agent
It helps in enhancing drug penetration and prolonging release.
What is ethanol’s role in transdermal formulations?
Solvent, permeation enhancer
Ethanol helps to dissolve the drug and enhance its penetration through the skin.
What is the function of propylene glycol in transdermal delivery?
Solvent, permeation enhancer
It aids in the solubility of drugs and enhances skin permeation.
What are carboxymethylcellulose and hydroxypropyl methyl cellulose used for?
Viscosity modifiers, matrix polymer
These compounds help control the viscosity and release of the drug.
What is the function of hyaluronate sodium in transdermal delivery?
Viscosity modifier, humectant, matrix polymer
Hyaluronate sodium retains moisture and enhances skin penetration.
What is calcium alginate used for in transdermal formulations?
Viscosity modifiers, adhesive, matrix polymer
It provides a gel-like consistency and helps in drug delivery.
What is the role of carbomer in transdermal delivery?
Viscosity modifier, adhesive
Carbomer helps to stabilize the formulation and control drug release.
What is poly(methyl vinyl ether/maleic anhydride) used for?
Viscosity modifier, adhesive
This compound is used to enhance the viscosity and adhesion of the formulation.
