Topical Retinoids

shevyatiwari's version from 2015-04-26 09:15


Question Answer
Tretinoin is a reduced form of all trans retinolF, oxidised
Tretinoin, all trans retinol and alitretinoin are naturally occurring retinoidsT
Adapalene, bexarotene and tazarotene are naturally occurring retinoidsF
Pregnancy tests should be done prior to any topical retinodisF, only bexarotene and tazarotene
Pregnancy is appropriate as long as the topical retinoid is not bexarotene or tazaroteneF, all should be avoided
all trans retinol is the natural form of vitamin AT
Adapalene is more stable compared to all-trans-retinoid acidT
Tretinoin is endogenously synthesised in the skin from all trans retinol after delivery of this compound to basal keratinocytesT
All trans retinol is transported from the liver via the blood stream via albuminF, via RBP (retinol binding protein)
All trans retinol traverses the papillary dermis and is taken up by the SCF, by basal keratinocytes
As basal keratinocytes divide, all trans retinol is taken up by drugs in the outer epidermis and diffuses through the skin as a fat soluble drugT
Excess all trans retinol is esterified to short chain fatty acidsF, long chain, to retinyl esters
ARAT is the enzyme system in keratinocytes important for endogenous all trans retinolF, for topically applied
LRAT is the enzyme system in keratinocytes important for endogenous all trans retinolT
All trans retinol binds to CRBP within the cell and is oxidised to all trans retinoid acidT
All trans retinol binds to CRABPF, all trans retinoic acid binds to CRABP
CRABP I is predominant in human skin and is the determining factor in the BA of retinoidsF, CRABPII
CRABPII transports all trans retinoid acid to the nucleus to bind to RAR and FABP5T
Inhibit excess sebum and P acne countsF. they DO provide an environment which is inhospitable for p acnes
Can be applied during the dayF, should be applied at night as is photo labile
Excess all trans retinol is esterified to retinyl estersT
Tretinoin is photolabileT - should be applied at night
Adapalene and tazarotene are photo labileF, unlike tretinoin. Can be applied morning or night
Inhibit ornithine decarboxylaserate limiting enzyme in the polyamine pathway


Question Answer
Available as 1% gel, cream and solution, and 3% gelF, 0.1 and 0.3
Similar to all trans retinolF, similar to all trans retinoic acid
More stable, less photo labile, more lipophilic allowing better follicle penetration than all trans retinoic acidT
Acts on RARB, RARY and anti AP1T
Binds to CRABPF, does not bind to cytosolic receptor protein - no affinity for CRABP but induces CRABPII mRNA if under occlusion for 4 days
Inhibits chemotaxis of PMNL's and release of ROS from neutrophilsT
Potentiates lipo-oxygenase pathyway and arachidonic acid metabolismF, inhibits
Selective uptake by folliclesT
After follicular penetration, adapalene undergoes dissolution within the sebum preventing systemic exposureT
Antiproliferative and proaptoptoticT
Decrease expression of TLR5 and IL10F, TLR2
Trace amounts that are absorbed are excreted renallyF, hepatobiliary
Carcinogenic, teratogenic, mutagenic and genotoxicF
PhotosensitisingF, however exercise caution in light
Erythema, dryness, scaling, pruritis, burning and stinging are commonT


Question Answer
The active drugF, a pro drug
Tazarotenic acid is an inactive metaboliteF, is the active metabolite
Tazarotenic acid binds to RXRF, only RARA and RARB
Downregulates TgaseI, EGF reeceptor, involucrin, SKALP, small praline rich protein 2, K6 and K16T
TIG1, 2 and 3 are present in high levels in psoriatic lesionsF low levels. Tazarotenic acid can induce TIG
Tazarotene undergoes hepatic metabolism to tazarotenic acidF, undergoes metabolism in the skin - hydrolysed
Systemic absorption is 5% on normal skin, and 15% in psoriatic skinT
Systemically absorbed tazarotene is excreted via the hepatobiliary routeF, urine and faeces
Mutagenic, carcinogenicF
Causes increased photocarcinogenicity in humansF, only in mice
Cat DF, X
No significant systemic, ophthalmologic, haematologic or clinical chemistry abnormalitiesT


Question Answer
Binds to RARF, RXR
Is a rexinoidT. BeXarotene is a reXinoid and binds to rXr
Available as 1% creamF, 1% gel
Inhibits S phase of cell cycleF, G1, G2 and M
Pro apoptoticT
Downregulates cyclin DT
Inhibits angiogenesisT
Increases TIMPT. These are tissue inhibitors of MMP. The result could help prevention of metastasis of certain tumours - therefore anti tumour effects
DEET coadministration -> increased toxicity of bexaroteneF, increases toxicity of DEET
Associated with central hypothyroidismF


Question Answer
Upregulates IL6F, downregulates - this is a growth factor for KS cells
Binds to no receptorsF, all
Higher affinity for RXR than RARF, other way around
RAR are associated with cellular differentiation whereas RXR are associated with apoptosisT
Cat XF, D
DEET should be avoidedT

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