Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Drug design wikipedia , lookup
Orphan drug wikipedia , lookup
Pharmacokinetics wikipedia , lookup
Drug discovery wikipedia , lookup
Neuropharmacology wikipedia , lookup
Pharmacogenomics wikipedia , lookup
Pharmaceutical industry wikipedia , lookup
Neuropsychopharmacology wikipedia , lookup
Prescription costs wikipedia , lookup
Pharmacognosy wikipedia , lookup
Psychopharmacology wikipedia , lookup
Prescription drug prices in the United States wikipedia , lookup
#3 skin pharmacology Pharmacology Shatha Kh. Shahwan 18-10-2015 Ahmad Tarifi Page 0 of 10 20 Skin pharmacology -Topical drugs are the drugs that you apply on the skin (Creams, ointments, lotions, patches (nicotinic patch)) -Systemic drugs run through the whole body (pills, IV, IM) The following are the aspects of comparison between the topical and the systemic drugs 1. Concentrations at the site of infection: topical drugs are more concentrated at the site of infection bcz you are applying the drug directly on the site of the infection 2. Side effects : the systemic drugs have more side effects, bcz the drug is going to run through your whole body, and it’s going to go to the brain, kidneys, GIT( note : the side effects of the topical drugs( usually it doesn’t have side effects ) increase when it’s applied for a long time or the amount that is being applied is more than enough (that it reaches a point where it can cause prominent side effects) 3. Hypersensitivity reaction in topical drugs is more prominent( Rash, minor inflammation, blisters) >>>> this is useful in skin test where we can test the patient if he is allergic to penicillin or not depending on the results of the skin test. 4. Half-life: topical drugs have longer half-life bcz it doesn’t get metabolized through the liver (systemic drugs: get metabolised) 5. Bacterial resistance : topical drugs cause more bacterial resistance than systemic drugs, bcz it has a longer half-life , besides some patients put an excess amount of the topical drug that eventually leads to bacterial resistance Page 1 of 10 6. Stability over time (packaging): systemic drugs ( pills ) last for a longer time, where topical drugs may dry and have to be thrown after a particular short period of time after opening. 7. Site of infection: superficial( we prefer to use topical drugs )/ deep ( systemic drugs ) How to start a topical treatment? 1. always clean the skin or wound before applying the topical medication, or a new dose of it, or between 2 topical medications, bcz skin encrustations and dead tissue harbor microorganisms, which might block the medications from reaching the infected area, also, applying a new medication over a previously applied medication might not help with preventing the infection, or it won’t provide the wanted therapeutic benefit 2. wash your hands before and after applying the medication 3.wear gloves 4 .follow the doctor instruction regarding the doses The forms of topical drugs Creams vs. Lotions 1.The base of a cream is oil( creams are thicker than lotions ) >>>> it’s used for the dry skin bcz it needs to be moisturized and hydrated Page 2 of 10 2.The base of a lotion is water ( lotions are more liquid and soft and easier to spread than creams ) >>>>>it’s used for oily skin Types of skin Normal Sensitive Oily skin: it’s shiny, usually have breakouts and pimples Dry skin: ashy skin, wrinkled, usually need botox after the age of 40 Combination skin: oily at the T zone (the forehead and the nose and the chin) and dry at the cheeks and the jaw line 3.Ointments Much more thicker and have a higher consistency and they are rarely used in cosmetics ( unlike creams and lotions ), usually used in drugs -Vehicles: The active ingredient’s “mode of transport” into the skin, the substance in which the active ingredient is dissolved (most of the active ingredients are in the form of powder so we have to dissolve them in something) -Lipophilic drugs usually penetrate into the skin faster than hydrophilic drugs. -Aqueous vehicles/ solutions deliver these lipophilic drugs faster than fatty vehicles. Page 3 of 10 Partition Equilibrium of Vehicle The relationship between the vehicle and the skin. If the active ingredient prefers one, it will leave/ “part” with the other. If the partition equilibrium shifts towards the skin: the active ingredient prefers the skin and will leave the vehicle. Good formulation. If the partition equilibrium shifts towards the vehicle: the active ingredient prefers the vehicle, and not very much of it will leave onto the skin. Bad formulation. Occlusion Covering part of the skin after application of a dermatological preparation ( cover it with a Material that won’t absorb the medication ) Can raise water content of the outermost skin layer from 10-20% to 5075% Hydration increases permeability, reduces barrier function. Occlusion therefore enhances the penetration of active drug ingredients into the skin. Page 4 of 10 Site of Administration We must take into consideration the nature of the area a drug will be used on. For hairy skin (the head) easily washable vehicle( patients won’t want greasy fatty material on their hair>>> not practical >> besides, that would decrease the compliance which is not good ) In wet skin folds (the armpits) avoid occlusive vehicles. Drugs applied in skin folds/ groins/ armpits generally leads to higher uptakebecause of the skin type (thin ) in these areas. (no need for occlusion ) . The drug is in spray form which is good No need for occlusion bcz it going to be absorbed very easily ( no greasy material, easily absorbed ) Page 5 of 10 Penetration rate Penetration rate is higher when applied on thin skin (behind the ear/ on eyelid/ scrotum) than on thick skin (palm of the hand/ sole of the foot and on top of the nails ). Damaged skin> intact skin. Hydrated skin > dry skin Concentration/ Surface Area The higher a drug concentration the more therapeutic it tends to be, as long as it stays within its therapeutic index. Drugs in high concentrations are better able to penetrate the skin. The larger a surface area being treated by a drug, the more a drug is retained in the body. Application Method One of the main aims of dermatological treatment is to restore the skin’s hydration (i.e. bring it back to a normal level) >>> normal hydration >>> normal barrier function( one of the most important skin function ) . Follow the application instructions on the package, wear gloves, applicator, etc (as previously mentioned) A rule of thumb is ‘wet on wet and fat on dry’. Liquid drug forms are applied on wetting skin parts. Page 6 of 10 Semi-solid forms with a high fat content are used for dry skin conditions (psoriasis). The skin is really dry and inflamed Skin Condition Damaged or pathologically changed skin marks an especially higher risk for inducing systemic side effects. This is because the natural barrier function of the skin is impaired. It may be reduced, other times it is completely absent. -the idea of occlusion is to increase the absorbance of the drug and to make the skin more hydrated and that happens by preventing the evaporation of the liquid - watery preparation will evaporate faster than oily preparation ( occluding formations ) >> will stay longer >>>increase the hydration of the skin Page 7 of 10 - when we increase the hydration of the skin >> the protein content will be diluted ( inside the skin we have proteins that makes high concentration)>> a lot of water >> dilution >> the concentration of the drug outside will be greater than the inside >>>>>>>>the drug goes in .( the occlusion enhances the absorbance of the drug ) Acute inflammation there is crusting and vesiculation >> we use something aqueous >> dry preparations or lotions Chronic >>> scaling or lignification>>>> increased keratinization of the skin >so we use> oily cream and ointments Ideal topical antimicrobial Specificity: specific for the microorganism that produces the disease Low bacterial resistance Non allergic Stable preparation Where do we use topical anti-microbial preparation? -Prophylaxis >>> in surgeries >>we use antimicrobial and anti-cyptic >>so that bacteria don’t get inside the body -Infective dermatitis and wounds -Reducing colonization >>Staph aureus( most bacteria )>>nares Page 8 of 10 -Management of Acne vulgaris We combine antimicrobial and Corticosteroids >>>>in treating >> Infective dermatosis Diaper dermatitis ( kids ) Otitis externa Impetiginized eczema (contagious condition (infection of the skin superimposed on eczema ( inflammatory condition ) القوباء Shatha Kh Shahwan Page 9 of 10