pKa & Ionization State Tool
Supports acids, bases, and up to 3 pKa values.
pKa & Ionization State Tool – Master Drug Ionization Instantly
Understanding how drugs ionize is essential in pharmacy. This pKa & Ionization State Tool helps students visualize how drugs behave at different pH levels. Whether you’re studying drug absorption or formulation design, this tool shows how ionization impacts solubility and permeability.
The tool offers two smart modes:
Forward Mode – Find % ionized and unionized using pKa and pH
Reverse Mode – Estimate pKa using known % ionized and pH
This is perfect for quick lab calculations, concept reinforcement, and exam prep.
Step 1: Choose a Mode
At the top of the tool, you’ll find a toggle:
Select Forward Mode if you know the pKa(s)
Select Reverse Mode if you know the % ionized and pH
Use the mode that matches your data.
Forward Mode: From pKa to % Ionized
In Forward Mode, you calculate how much of a drug is ionized or unionized at a given pH.
🔸 Input Fields:
Compound Type: Choose Acidic or Basic
Number of pKa Values: Select 1 to 3 (monoprotic or polyprotic)
Enter pKa Values: Add all relevant pKa values
Enter pH: Input the environmental pH (e.g., blood, stomach)
Temperature (Optional): Input for temperature context (default = 25°C)
🔸 Output:
% Ionized and % Unionized: For each ionization step
Dominant Form: Indicates which form is predominant
Interpretation: Suggests solubility or membrane absorption
Chart: Pie or bar chart for easy visualization
Calculation Breakdown: Shows each step using the Henderson-Hasselbalch equation
This helps you see how a drug’s behavior changes in different pH environments.
Reverse Mode: Estimate pKa from pH and % Ionized
In Reverse Mode, you estimate the drug’s pKa based on known ionization data.
🔸 Input Fields:
Compound Type: Select Acidic or Basic
Enter pH: Provide the environmental pH
Enter % Ionized: Approximate how much of the drug is ionized
⚠ This mode assumes the compound is monoprotic. For polyprotic drugs, it calculates the primary ionization step only.
🔸 Output:
Estimated pKa
% Unionized
Dominant Form
Formula Used: With calculation steps
This is ideal for reverse-calculating values in pharmacokinetics and formulation questions.
Real-Time Visualization & Export
Built with Chart.js
Graph updates instantly
Color-coded chart shows ionization split
Click Export to PNG or PDF to download:
Input summary
Results
Visual chart
Perfect for lab reports or presentations.
When to Use This Tool?
In pharmacokinetics assignments
During formulation and biopharmaceutics labs
For exam revision on acid-base drug behavior
In research reports comparing drug solubility at different pH levels
