Description
Fluconazole-D4 is the f i t member of a new generation of stable and orally active antifungals, the triazoles. It is highly effective in the treatment of dermal and vaginal fungal infections; new indications currently under investigation include severe systemic mycoses such as disseminated candidiasis and cryptococcal meningitis in immunocompromised patients.
Originator
Pfizer (United Kingdom)
Definition
ChEBI: Fluconazole is a member of the class of triazoles that is propan-2-ol substituted at position 1 and 3 by 1H-1,2,4-triazol-1-yl groups and at position 2 by a 2,4-difluorophenyl group. It is an antifungal drug used for the treatment of mucosal candidiasis and for systemic infections including systemic candidiasis, coccidioidomycosis, and cryptococcosis. It has a role as a P450 inhibitor, an environmental contaminant and a xenobiotic. It is a difluorobenzene, a conazole antifungal drug, a triazole antifungal drug and a tertiary alcohol. It is functionally related to a 1,3-difluorobenzene. It derives from a hydride of a 1H-1,2,4-triazole.
Indications
Fluconazole (Diflucan) may be better absorbed and is
possibly less hepatotoxic than ketoconazole, but it is
considerably more expensive, an important consideration
given the required length of therapy for most cutaneous
fungal diseases.
Manufacturing Process
141.1 g of aluminum trichloride was first added to 86 ml of DFB and 77 ml of chloroacetyl chloride was then added to the mixture, which was allowed to
react at 60°C for 3 hours. After the reaction mixture had cooled down, 500 g
of cold water was added. The mixture was stirred for about 20 min and then
filtered to afford about 158.5 g of 2-chloro-2',4'-difluoroacetophenone in solid
form (91% yield).
A solution of 158.5 g of 2-chloro-2',4'-difluoroacetophenone and 88.8 g of 4-
amino-4H-1,2,4-triazole in 1,600 ml of cyanomethane was heated at reflux for
16 hours, cooled down, and filtered. The solid thus obtained was then washed
with 500 ml of ethyl ether once to afford 2-(1H-1,2,4-triazol-1-yl)-2',4'-
difluoroacetophenone salt.
The crude product obtained was dissolved in 1,320 ml of 1.5 N hydrochloric
acid. To the solution thus obtained, an aqueous solution (330 ml) of sodium
nitrite (58.2 g) was dropwise added and the mixture was allowed to react for
30 min. Aqueous ammonium was then used to adjust the reaction mixture to
a neutral pH. The solid was precipitated and filtered to afford 159 g of 2-(1H-
1,2,4-triazol-1-yl)-2',4'-difluoroacetophenone (yield about 80%), which had a
water content of about 10%.
4 g of 4-amino-4H-1,2,4-triazole, 57.87 g of potassium hydroxide, 118 g of
trimethyl sulfoxonium iodide, and 100 g of 2-(1H-1,2,4-triazol-l-yl)-2',4'-
difluoroacetophenone were dissolved in 1,600 ml of water. The solution was
heated at 70°C to react for 16 hours. Upon the completion of the reaction, the
solution was adjusted with 4 N hydrochloric acid to a neutral pH and then
extracted with acetyl acetate. The organic layer was collected, dried with 30 g
of anhydrous calcium dichloride, decolorized with 15 g of active charcoal, and
finally filtered off solid residues. The filtrate was concentrated to afford 99.3 g
of the crude product (yield 72%). The crude product was further recrystallized
from 500 ml of a solvent mixture of acetyl acetate and n-hexane (2:1) to
afford 66.3 g of the Fluconazole in the form of white solid (yield 48%).
Brand name
Diflucan (Pfizer).
Therapeutic Function
Antifungal
Antimicrobial activity
The spectrum is limited, but includes most Candida spp.,
Cryptococcus spp., dermatophytes and dimorphic fungi (Blast.
dermatitidis, Coccidioides spp., Hist. capsulatum and Paracoccidioides
brasiliensis). Strains of C. krusei appear to be insensitive.
Acquired resistance
Resistant strains of C. albicans have been isolated from AIDS
patients given long-term treatment for oral or esophageal
candidosis. Strains of C. glabrata frequently become resistant
during short courses of treatment. There are a few reports
of fluconazole-resistant strains of Cryp. neoformans recovered
from AIDS patients with relapsed meningitis. Most, but not
all, C. albicans and C. glabrata strains resistant to fluconazole
are cross-resistant to other azoles.
General Description
Fluconazole is used to treat adult neutropenic patients with invasive candidiasis (IC).
Pharmaceutical Applications
A synthetic bis(triazole) available for oral or parenteral administration.
A prodrug formulation, fosfluconazole, is available
for intravenous use in Japan.
Biological Activity
Triazole antifungal agent. Effective against Candida strains in vitro and in vivo .
Biochem/physiol Actions
Fluconazole is an antifungal agent. It is highly selective inhibitor of fungal cytochrome P-450 sterol C-14 α-demethyllation. Fluconazole is a potent inhibitor of CYP2C9. Fluconazole interferes with fungal ergosterol synthesis and downregulates the metallothionein gene.
Pharmacokinetics
Oral absorption: >93%
Cmax 50 mg oral: c. 1 mg/L after 2 h
Plasma half-life: 25–30 h
Volume of distribution: 0.6–0.8 L/kg
Plasma protein binding; <10%
Absorption
Oral absorption is rapid (1–3 h) and is not affected by food or intragastric pH. Blood concentrations increase in proportion to dosage. Maximum serum concentrations increase to about 2–3 mg/L after repeated dosing with 50 mg.
Distribution
It is widely distributed, achieving therapeutic concentrations in most tissues and body fluids. Concentrations in cerebrospinal fluid (CSF) are 50–60% of the simultaneous serum concentration in normal individuals and even higher in patients with meningitis.
Metabolism and excretion
More than 90% of an oral dose is eliminated in the urine: about 80% as unchanged drug and 10% as inactive metabolites. The drug is cleared by glomerular filtration, but there is significant tubular reabsorption. The plasma half-life is prolonged in renal failure, necessitating adjustment of the dosage.Fluconazole-D4 is removed during hemodialysis and, to a lesser extent, during peritoneal dialysis. In children the volume of distribution and plasma clearance are increased, and the half-life is considerably shorter (15–25 h).
Pharmacology
It has good oral absorption,
is well tolerated, and is preferentially taken up in keratinized tissues, reaching
concentrations up to 50 times that in plasma. This allows for once-weekly
dosing in most cases.
Clinical Use
Fluconazole is very effective in the treatment of infections
with most Candida spp. Thrush in the end-stage
AIDS patient, often refractory to nystatin, clotrimazole,
and ketoconazole, can usually be suppressed with oral
fluconazole.AIDS patients with esophageal candidiasis
also usually respond to fluconazole.
Fluconazole may be an acceptable alternative to
amphotericin B in the initial treatment of mild cryptococcal
meningitis, and it has been shown to be superior
to amphotericin B in the long-term prevention of relapsing
meningitis (such patients require lifelong treatment.).
Coccidioidal meningitis, previously treated with
both intravenous and intrathecal amphotericin B, appears
to respond at least as well to prolonged oral fluconazole
therapy. Aspergillosis, mucormycosis, and
pseudallescheriasis do not respond to fluconazole treatment.
Sporotrichosis, histoplasmosis, and blastomycosis
appear to be better treated with itraconazole, although
fluconazole does appear to have significant activity
against these dimorphic fungi.
Clinical Use
Mucosal, cutaneous and systemic candidosis
Coccidioidomycosis
Cryptococcosis
Dermatophytosis
Pityriasis versicolor
Side effects
Fluconazole is well tolerated. Nausea, vomiting, abdominal
pain, diarrhea, and skin rash have been reported in
fewer than 3% of patients. Asymptomatic liver enzyme
elevation has been described, and several cases of drugassociated
hepatic necrosis have been reported. Alopecia
has been reported as a common adverse event in
patients receiving prolonged high-dose therapy. Coadministration
of fluconazole with phenytoin results in increased
serum phenytoin levels.
Side effects
These are rare, but untoward reactions include nausea,
abdominal discomfort, diarrhea and headache. Transient
abnormalities of liver enzymes and rare serious skin reactions,
including Stevens–Johnson syndrome, have been
reported.
Veterinary Drugs and Treatments
Fluconazole may have use in veterinary medicine in the treatment
of systemic mycoses, including cryptococcal meningitis, blastomycosis,
and histoplasmosis. It may also be useful for superficial
candidiasis or dermatophytosis. Because of the drug’s unique pharmacokinetic
qualities, it is probably more useful in treating CNS
infections or fungal urinary tract infections than other azole derivatives.
Fluconazole does not have appreciable effects (unlike ketoconazole)
on hormone synthesis and may have fewer side effects
than ketoconazole in small animals.
Drug interactions
Potentially hazardous interactions with other drugs
Aminophylline: concentration of aminophylline
possibly increased.
Analgesics: increases concentration of celecoxib -
halve celecoxib dose; concentration of flurbiprofen,
ibuprofen and methadone increased; increases
concentration of parecoxib - reduce parecoxib dose;
inhibits metabolism of alfentanil; concentration of
fentanyl possibly increased.
Anti-arrhythmics: avoid concomitant use with
amiodarone due to risk of QT prolongation.
Antibacterials: avoid with erythromycin; increases
rifabutin levels - reduce dose; metabolism
accelerated by rifampicin; concentration of
bedaquiline possibly increased - avoid if fluconazole
for >14 days.
Anticoagulants: potentiates effect of coumarins.
Antidepressants: avoid concomitant use with
reboxetine; concentration of amitriptyline and
nortriptyline increased.
Antidiabetics: possibly enhances hypoglycaemic
effect of nateglinide; increases concentration of
sulphonylureas.
Antiepileptics: increases fosphenytoin and
phenytoin levels; possibly increased carbamazepine
concentration.
Antimalarials: avoid concomitant administration
with artemether/lumefantrine and piperaquine with
artenimol.
Antipsychotics: increased risk of ventricular
arrhythmias with pimozide - avoid concomitant
use; possibly increases lurasidone concentration;
possibly increased quetiapine levels - reduce dose of
quetiapine.
Antivirals: increases nevirapine, ritonavir, tipranavir
and zidovudine levels, and possibly saquinavir:
concentration of simeprevir possibly increased -
avoid.
Anxiolytics and hypnotics: increases diazepam and
midazolam levels.
Avanafil: concentration of avanafil possibly increased.
Bosentan: increased bosentan levels - avoid
concomitant use.
Ciclosporin: increases blood/serum ciclosporin
levels.
Clopidogrel: possibly reduced antiplatelet effect.
Cytotoxics: possibly increased side effects of
cyclophosphamide; concentration of bosutinib and
possibly olaparib increased - avoid or reduce dose of bosutinib; possibly increases ibrutinib concentration
- reduce ibrutinib dose; reduce dose of ruxolitinib.
Dapoxetine: reduce dose of dapoxetine.
Diuretics: increased eplerenone levels - avoid
concomitant use; concentration of fluconazole
increased by hydrochlorothiazide.
Ergot alkaloids: increased risk of ergotism - avoid
concomitant use.
Guanfacine: possibly increased guanfacine dose -
halve dose of guanfacine.
Ivabradine: increased ivabradine levels - reduce
initial dose.
Ivacaftor: increased concentration of ivacaftor.
Lipid-lowering drugs: possibly increased risk
of myopathy with atorvastatin or simvastatin;
concentration of fluvastatin increased possibly
increased risk of myopathy; avoid with lomitapide.
Retinoids: possibly increased risk of tretinoin
toxicity.
Sirolimus: may increase sirolimus concentration.
Tacrolimus: increases blood/serum tacrolimus levels.
Theophylline: possibly increases theophylline levels.
Metabolism
Fluconazole is metabolised only to a minor extent. Of
a radioactive dose, only 11% is excreted as metabolites
in the urine. The major route of excretion is renal, with
approximately 80% of the administered dose appearing in
the urine as unchanged medicinal product. Fluconazole
clearance is proportional to creatinine clearance. There is
no evidence of circulating metabolites.