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Regarding Dapsone.... Contraindications

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shevyatiwari's version from 2015-08-23 12:29

Section 1

Question Answer
Prior hypersensitivity is an absolute contraindication T. Absolute contraindication
Previous hypersensitivity syndrome an absolute contradication T. Absolute contraindication
Agranulocytosis is an absolute contradication T. Absolute contraindication
G6PD deficiency is an absolute contradication F. Relative
Allergy to sulphonamides is a relative contraindication T. Relative
Significant cardiopulmonary disease is an absolute contradication F. Relative
Significant liver or renal disease is a relative contraindication T. Relative
Pre-exisiting peripheral peripheral neuropathy is not a contraindication F. Relative C/I
Pregnancy CatC
Quenches free radicals T
Effects chemotaxis of neutrophils T
Dapsone inhbits myeloperoxidase also found in eosinophils and monocytesT
Two major metabolites of Dapsone MADDS and DDSOH possess intrincic antinflamm properties of their ownT
Rapid response to treatment T 24-48hrs
Rapid recurrence after cesstion of DapsoneT
Dapsone treatment of choice for DH but gluten free diet also effective T
Toxicity directly related to dose of drug T. Pts should be warned not to self administer or dose adjust
Topical 5% can be used for acne in kids >12 T
cross -sensitivity between dapsone and sulfapyridine or sulfonamides is commonF. RARE - even in JIV infected pts with documented tmp/smx allergy
memorize

Section 2

Adverse Effects
Question Answer
Haemolytic anaemia and Methhaemoglobulinaemia True and dose realted. Methem - may present as headache and lethargy
leucopenia and agranulocytosis are dose related F. Idiosyncratic. Only hemolyitc anaemia and meth haem are dose related
Hepatic - transminitis T
Infectious monomucleois -like syndrome T
Cholestatic jaundice and hypoalbuminaemia are commonly associated F. Rare
Pancreatitis False. not reported
Morbilliform eruption and TEN T. and exfoliative erythroderma
GI upset and nauseaT
Depression F.
Psychosis T
peripheral neuropathy T - MOTOR - D.M doc marten
memorize

Section 3

Question Answer
Heamolytic anaemia and methemoglobulinaemia predicatable and dose related True ,. Pharmacological effects NOT idiosynbratic
Oral methylene blueu 100-300mg/day can be use to treat ALL high methemoglobin levels False . Contraindicated and ineffective if pt G6PD deficient
Agranulocytosis most serious idiosyncratic reaction to dapsone True. mechanism unknown
median duration of therapty prior to agranulocytois is 7 weeks True . range 3-12 weeks
All cases of agran develop within first 12 weeks fo therapy True
granulocyte colony-stimulating factor has been used to speed granulocyte recovery True
pts shoule cease medications if they develop persisant fevers or flu-like symptoms True
Drug induced hepatitis can occur True
memorize

Section 4

Question Answer
Interactions
= Drugs that decrease serum Dapsone levels
St. johns wort T decrease serum Dapsone levels via CYP3A4 ENZYME INDUCTION
rifamycins T decrease serum Dapsone levels
anticonvulsants T decrease serum Dapsone levels
griseofulvin T decrease serum Dapsone levels
HIV drugs ef, nevirapineT decrease serum Dapsone levels
Bosentan - for pulmonary hypertension T decrease serum Dapsone levels
memorize

Section 5

Question Answer
Antacids , PPT, H2 antihistamines decrease serum levels True . Decrease efficacy via decreased GI absorption (also AL, Ca and Mg )
HIV drugs have no effect on serum leverls F. Didanosine may decrease GI absorption . Give 2 hours apart
Antiemetics may decrease serum levels T APREPITANT MAY BOTH INCREASE AND DECREASE DAPSONE LEVELS
Probencid may decrease levels F. increase levels and potentially increase toxicity
Sulfonamides may increase haematological risk of Dapsone T. Dihydropteroate synthetase inhibitors eg/ sulphonamides - as inhibit same enxyme as Dapsone
Dihydrofolate reductase inhbitis do not increase Hematological Sx of dapsone F. MTX, PYRIMETHAMINE, TRIMEXATE, TRIMETHOPRIM, all may increase haem tisk
Zicalcitibine HIV drug may increase risk of peripheral neuropathy T - additive risk for peripheral neuropathy
PABA may decrease efficacy of Dapsone via folate metabolic pathwayT
Sulphonamides may increase oxidative stress to RBC - result in hemolysis and methemoglobinemiaT
LA may increase oxidative stress to RBC - result in hemolysis and methemoglobinemiaT eg. benzocaine , prilocaine (with lidocaine EMLA)
Chloroquine, HCQ and primiquine increase hemolysis risk T and methem risk
Nitroprussside increase hemolysis risk T and methem risk
memorize