ID: is also not known if it passes to

ID:
201510317

Student’s
name: Altaf Hani

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In pregnancy it
can only be given when the benefits exceed the harm of it on the pregnancy, it
is also not known if it passes to the baby through the breast milk, so patient
should not breastfeed during using the drug.

Blood and Liver
toxicities may occur with 5-FC intake, but can be minimized by monitoring serum
concentrations and by managing the dose carefully in pts with renal impairment.
When its not available to check for serum concentration, careful monitoring for
cytopenias is necessary.

·        
Pts with bone marrow failure and liver failure should
be treated with caution.

·        
Pts with
kidney disease should take flucytosine in reduced doses.

·        
Pts who are
using this drug have deacresed bone marrow function , so should be treated
carefully. CBC should be
done frequently.

S. E. :

After an oral intake of 2 gm peak serum levels are obtained after
approx. 6 h, the time to peak level goes down with cont. therapy. The drug is excreted
from the kidneys. In healthy pts flucytosine has a half-life of 2.5 to 6hs. In
patients with renal failure, more serum levels are noted & the medicine
accumulate. It is mainly excreted without change in the urine and only
metabolized and excreted in the feces.

Flucytosine is absorbed from the GIT. Taking it with meals slow the absorption,
but will not decrease the amount absorbed.

Pharmacokinetics

·        
Flucytosine
goes conversion into 5-FDUP that inhibits fungal DNA synthesis.

·        
Flucytosine
is intrafungally converted into the cytostatic fluorouracil that goes for further steps of activation and finally interacts as 5-FUT
with RNA biosynthesis soi t changes the organisation of some important  proteins.

Two mechanisms have been
reported :

Action

Flucytosine, as
5-fluorocytosine (5-FC), it is an antifungal drug . It has to be used in a company with amphotericin B, in serious Candida infections and cryptococcosis. Pt can use it by
itself or with other antifungals for chromomycosis. Flucytosine
can be given orally or I.V.

 

 

 

·        
Teratogenic, so should be avoided in pregnancy

·        
It is
necessary to adjust the dose in liver disease

Not to go for it :

·        
No need to
change the dose based on age, gender, race

·        
Does not
affect those with renal failure and hemodialysis

·        
minimum amount of toxicity

·        
extended half-life
(alpha phase 1–2 h + beta phase 9–11 h + gamma phase 40–50 h)

·        
Wide range (specially
against Candida),

To go for it :

All echinocandins have minimal oral bioavailability & the only way
of administration is via intravenous route. Because no one of the medicines is
excreted by the kidneys, the dose does not need to be changed for those with
renal failure or problem. In mild to moderate hepatic failure, the dose of
caspofungin has to be changed but this change is not as important for
anidulafungin & micafungin.

Pharmacokinetics

The echinocandins play a role
of a non competitive inhibitors of ? – (1, 3) – D-glucan synthase,
an important component of the fungal cell wall. Uncapability  of the organism to synthesize ? – (1, 3) –
D-glucan will lead to osmotic abnormalities & the cell will die.

Action

Aspergillus species, echinocandins shows fungistatic affect same as
amphotericin B & trizoles, that shows fungicidal affect. Echinocandin
resistance, is not common, was only recorded with C. glabrata & C.
Parapsilosis.

Echinocandins shows good fungicidal affect against Candida albicans,
Candida parapsilosis & Candida guilliermondii. A good result
recorded against amphotericin B-resistant & fluconazole-resistant Candida
glabrata.

 

 

 

Echinocandins are basically group
of semisynthetic, cyclic lipopeptides with an N-linked acyl lipid side chain,
involving subtypes : caspofungin, micafungin & anidulafungin.

Antifungal spectrum