Oral and Intravenous Fluconazole 200 mg Are Therapeutically Equivalent
Yes, tablet fluconazole 200 mg is essentially equivalent to intravenous fluconazole 200 mg due to the drug's exceptional oral bioavailability of approximately 90%, resulting in nearly identical systemic concentrations regardless of route. 1
Pharmacokinetic Basis for Equivalence
Fluconazole demonstrates oral bioavailability of approximately 90%, meaning oral administration achieves concentrations equal to ~90% of those achieved by intravenous administration 1
Absorption is not affected by food consumption, gastric pH, or disease state, making oral dosing highly reliable across different clinical scenarios 1
The drug's high water solubility and metabolic stability contribute to its consistent absorption and therapeutic activity 2
Clinical Implications for Route Selection
The choice between oral and intravenous formulations should be based solely on the patient's ability to swallow, not on concerns about efficacy:
For patients who can swallow, oral fluconazole 200 mg is the preferred route due to convenience, cost-effectiveness, and equivalent therapeutic outcomes 1
Intravenous fluconazole should be reserved for patients unable to tolerate oral therapy (e.g., severe esophagitis, altered mental status, intubation) 1, 3
For esophageal candidiasis specifically, guidelines explicitly state that "intravenous formulation can be used in case of severe oesophagitis" when oral administration is not feasible 1
Dosing Considerations
Both routes require the same total daily dose (e.g., 200 mg daily for esophageal candidiasis, 400 mg daily for invasive candidiasis) 1
Loading doses apply equally to both routes (800 mg loading dose for invasive candidiasis, regardless of formulation) 1
Renal dose adjustment is required for both formulations when creatinine clearance is <50 mL/min, as elimination is primarily renal 1
Important Caveats
The long elimination half-life of 22-32 hours means steady-state takes approximately 6 days to achieve with either route, making loading doses particularly important 4, 5
Switching between oral and intravenous formulations mid-treatment requires no dose adjustment due to bioequivalence 1
The low protein binding (11-12%) and extensive tissue distribution are identical regardless of administration route 4, 5