1. What is Bioavailability?

Bioavailability is the systemically available fraction of a drug that reaches the systemic circulation and is available at the site of action. It is a crucial pharmacokinetic parameter that determines the effectiveness of drug administration.

2. How Does the Calculator Work?

The calculator uses the bioavailability formula:

Where:

• \( B \) — Bioavailability (unitless fraction)
• \( De \) — Effective Dose (kg)
• \( Q \) — Drug Purity (expressed as decimal)
• \( Da \) — Administered Dose (kg)

Explanation: This formula calculates the fraction of administered drug that reaches systemic circulation, accounting for drug purity and dosage effectiveness.

3. Importance of Bioavailability Calculation

Details: Bioavailability is essential for determining appropriate drug dosing, comparing different drug formulations, and ensuring therapeutic effectiveness while minimizing side effects.

4. Using the Calculator

Tips: Enter effective dose and administered dose in kilograms, drug purity as a percentage. All values must be positive numbers. Drug purity should be between 0-100%.

5. Frequently Asked Questions (FAQ)

Q1: What is considered good bioavailability?
A: Bioavailability values range from 0 to 1 (or 0-100%). Generally, values above 0.8 (80%) are considered excellent, while values below 0.3 (30%) may require dosage adjustments.

Q2: How does drug purity affect bioavailability?
A: Lower drug purity reduces the amount of active ingredient available for absorption, thereby decreasing bioavailability if not compensated by increased dosage.

Q3: What factors influence bioavailability?
A: Factors include drug formulation, administration route, first-pass metabolism, solubility, stability, and patient-specific factors like age and health status.

Q4: How is bioavailability measured experimentally?
A: Typically measured by comparing the area under the curve (AUC) of plasma concentration versus time after different administration routes.

Q5: Why is bioavailability important in drug development?
A: It helps determine optimal dosing, compare formulations, and ensure consistent therapeutic effects across different patient populations.