Microbiology and Pharmacology Flashcards
What are the main virulence factors and their functions?
- adhesin: enables the binding of organism to the host tissue
- impedin: enables the organism to avoid host defence
- aggressin: damage to host directly
What are the main features of Staph?
- colonises skin and mucous membranes
- can cause superficial lesions and systemic issues such as toxic shock which is caused by TSST-1
- PVL is in extreme skin infections and leads to sepsis and necrotising fasciitis
What are the main features of TSST-1?
this is a super antigen which stabilises immune reaction and causes both release of cytokines and toxic menstrual shock
What are the main features of Strep?
- normally in the pharynx
- Lancefield classification of surface antigens
- is bacterial sore throat, impetigo, cellulitis and necrotising fasciitis (strep A destroys connective tissue)
How do drugs move into the skin?
if the drug is hydrophobic then it can move in by massive diffusion and remain in the lipid layer around the corneocytes
How is the rate of drug absorption described mathematically?
by Fick’s Law according to the vehicle
What is an excipient?
this is a substance that can be put in the vehicle that can enhance solubility
What is a good way to administer a drug for a long time at a steady plasma concentration?
trans-dermal patch
What is the best way to improve partitioning?
- hydration of the skin by occlusion with type of vehicle or cling film
- inclusion of excipients to increase solubility of the drug
What effects do glucocorticoids have on the skin?
- anti-inflammatory
- immunosuppressive
- vasoconstricting
What conditions are glucocorticoids used to treat?
atopic eczema, psoriasis and pruritus
What are the side-effects of long-term steroid use?
- steroid rebound
- skin atrophy
- systemic effects
- infection
- steroid rosacea
- stretch marks
How do glucocorticoids act?
- signal via GRalpha receptors
- enter cells by diffusion and then they combine with GRa
- the receptor moves to nucleus and assembles into a homodimer
- binds to glucocorticoid response elements in the promoter region
- switch on or off of genes
What is TTD?
transdermal drug delivery is good for steady state drug delivery and avoids first-pass metabolism
however, only some drugs are suitable
What are the + and - for subcutaneous drug administration?
+ slow absorption
+ slow constant release
- injection volume limited
What are the advantages of topical treatments?
there is direct application and reduced systemic effects
What are the disadvantages of topical treatments?
they are time consuming, correct dosage can be difficult and they are messy
What are the features of creams?
- non-greasy
- semisolid emulsion of oil in water
- high water content
What are the features of ointments?
- semi-solid grease or oil
- no preservative
- occlusive and restrict water loss from the skin
- very greasy
What are the features of lotions?
- liquid
- might sting
- good for scalp or hair-bearing areas
What are the features of gels?
- thickened solutions
- semi-solid
- treat scalp, face and other hair-bearing areas