Astartes
Well-known Member
Disclaimer: Realize this may have been posted somewhere before, but thought it would be relevant to summarize in detail again as so many people have continued to ask and be confused.
(Please check my math)
Here’s the detailed process I use for calculating and filling size 1 capsules (as an example) with medication and an inert filler. This guide includes the pharmaceutical math equations, steps for solving volume-to-mg ratios, and how to calculate capsule weight by weighing 10 empty capsules to get an average. This is based on current and reliable pharmaceutical compounding practices.
Step 1: Understanding Capsule Size and Capacity
• Size 1 capsule volume = 0.50 mL (500 µL)
• This is the space inside the capsule that will be filled with both the active drug and the filler.
Approx. Capsule Size,Volume (mL)
000————————-1.37 - 1.40 mL
00—————————0.90 - 0.95 mL
0—————————-0.68 - 0.70 mL
1—————————-0.50 mL
2—————————-0.37 mL
3—————————-0.30 mL
4—————————-0.21 mL
5—————————-0.13 mL
Step 2: Calculate the Fill Weight
The fill weight is the amount of powder (both active drug and filler) that will fit into the capsule based on the bulk density of the powder.
Formula:
Fill Weight (mg) = Bulk Density (mg/mL) * Capsule Volume (mL)
Example:
If the bulk density of the powder is 0.8 g/mL (800 mg/mL), the calculation for a size 1 capsule would be:
Fill Weight = 800 mg/mL * 0.50 mL = 400 mg
Step 3: Calculate the Medication and Filler Amounts
Now that you know the total fill weight, you can calculate the amount of the active drug and the inert filler required for each capsule.
Formula for Filler Weight:
Filler Weight = Total Fill Weight - Drug Weight
Example:
• Total Fill Weight = 400 mg (from Step 2)
• Drug Weight = 50 mg
Filler Weight = 400 mg - 50 mg = 350 mg
So, you’ll need 50 mg of the active drug and 350 mg of filler (e.g., lactose or starch) for each capsule.
Step 4: Weighing 10 Empty Capsules to Calculate Average Weight
To ensure accuracy, it’s important to weigh several empty capsules and average the weight to use in further calculations.
Process:
1. Weigh 10 empty capsules on a precision scale.
2. Record the total weight of the 10 capsules.
3. Divide the total weight by 10 to find the average weight of one empty capsule.
Example:
• Total weight of 10 empty capsules = 750 mg
Average Capsule Weight = Total Weight / 10
Average Capsule Weight = 750 mg / 10 = 75 mg
Step 5: Calculate the Total Weight of a Filled Capsule
Once you know the fill weight and the average weight of the empty capsule, you can calculate the total weight of the filled capsule.
Formula:
Filled Capsule Weight = Fill Weight + Average Empty Capsule Weight
Example:
• Fill Weight = 400 mg (from Step 2)
• Average Empty Capsule Weight = 75 mg (from Step 4)
Filled Capsule Weight = 400 mg + 75 mg = 475 mg
Step 6: Geometric Dilution for Blending
To ensure uniform distribution of the active drug in each capsule, use geometric dilution when mixing the drug with the filler.
Process:
1. Start with organic dye powder or Pharma dye. (Subtract amount from filler volume/weight)
2. Mix a small, equal amount of the active drug and filler together.
3. Gradually add more filler in small increments, blending thoroughly after each addition.
4. Continue until all of the filler is mixed in.
This method ensures that the drug is evenly distributed throughout the mixture, which is crucial for consistent dosing.
Step 7: Volume-to-Weight Conversion (if needed)
If you need to convert the weight of the powder to volume or vice versa, use the following formula based on the bulk density.
Formula:
Volume (mL) = Weight (mg) / Bulk Density (mg/mL)
Example:
If you have 100 mg of the drug and its bulk density is 0.8 g/mL (800 mg/mL):
Volume = 100 mg / 800 mg/mL = 0.125 mL
This means the drug will occupy 0.125 mL of the 0.50 mL total capsule volume, with the rest filled by the inert filler.
Example Calculation for Filling Size 1 Capsules
Let’s say you’re making size 1 capsules that need 50 mg of active drug per capsule, with lactose as a filler. The bulk density of lactose is 0.8 g/mL.
1. Calculate Total Fill Weight:
Fill Weight = 800 mg/mL * 0.50 mL = 400 mg
2. Calculate Filler Weight:
Filler Weight = 400 mg - 50 mg = 350 mg
3. Weigh Empty Capsules:
• Total weight of 10 capsules = 750 mg
• Average Capsule Weight = 750 mg / 10 = 75 mg
4. Calculate Filled Capsule Weight:
Filled Capsule Weight = 400 mg + 75 mg = 475 mg
**IMPORTANT FOR USING CAPSULE MAKERS**
To scale your formula for filling 100 capsules, you can use simple proportion math.
Step 1: Calculate the total amount of drug and filler for 1 capsule
• If each capsule contains 50 mg of drug and 350 mg of filler, the total fill weight is 400 mg per capsule.
Step 2: Scale to 100 capsules using proportion
To scale up for 100 capsules, simply multiply the amount for 1 capsule by 100.
Formulas:
1. Drug amount for 100 capsules:
Drug for 100 capsules = Drug per capsule * 100
Example: 50 mg * 100 = 5000 mg (or 5 g)
2. Filler amount for 100 capsules:
Filler for 100 capsules = Filler per capsule * 100
Example: 350 mg * 100 = 35000 mg (or 35 g)
3. Total mixture amount for 100 capsules:
Total mixture for 100 capsules = Total fill weight per capsule * 100
Example: 400 mg * 100 = 40000 mg (or 40 g)
Step 3: Adjust for losses (Optional)
It’s a common practice to prepare extra powder (e.g., for 2 additional capsules) to account for losses during filling.
Formula to adjust for losses:
Total for 102 capsules = Total fill weight per capsule * 102
Example: 400 mg * 102 = 40800 mg (or 40.8 g)
By using these formulas, you can scale any formula to larger batch sizes as needed.
(Please check my math)
Here’s the detailed process I use for calculating and filling size 1 capsules (as an example) with medication and an inert filler. This guide includes the pharmaceutical math equations, steps for solving volume-to-mg ratios, and how to calculate capsule weight by weighing 10 empty capsules to get an average. This is based on current and reliable pharmaceutical compounding practices.
Step 1: Understanding Capsule Size and Capacity
• Size 1 capsule volume = 0.50 mL (500 µL)
• This is the space inside the capsule that will be filled with both the active drug and the filler.
Approx. Capsule Size,Volume (mL)
000————————-1.37 - 1.40 mL
00—————————0.90 - 0.95 mL
0—————————-0.68 - 0.70 mL
1—————————-0.50 mL
2—————————-0.37 mL
3—————————-0.30 mL
4—————————-0.21 mL
5—————————-0.13 mL
Step 2: Calculate the Fill Weight
The fill weight is the amount of powder (both active drug and filler) that will fit into the capsule based on the bulk density of the powder.
Formula:
Fill Weight (mg) = Bulk Density (mg/mL) * Capsule Volume (mL)
Example:
If the bulk density of the powder is 0.8 g/mL (800 mg/mL), the calculation for a size 1 capsule would be:
Fill Weight = 800 mg/mL * 0.50 mL = 400 mg
Step 3: Calculate the Medication and Filler Amounts
Now that you know the total fill weight, you can calculate the amount of the active drug and the inert filler required for each capsule.
Formula for Filler Weight:
Filler Weight = Total Fill Weight - Drug Weight
Example:
• Total Fill Weight = 400 mg (from Step 2)
• Drug Weight = 50 mg
Filler Weight = 400 mg - 50 mg = 350 mg
So, you’ll need 50 mg of the active drug and 350 mg of filler (e.g., lactose or starch) for each capsule.
Step 4: Weighing 10 Empty Capsules to Calculate Average Weight
To ensure accuracy, it’s important to weigh several empty capsules and average the weight to use in further calculations.
Process:
1. Weigh 10 empty capsules on a precision scale.
2. Record the total weight of the 10 capsules.
3. Divide the total weight by 10 to find the average weight of one empty capsule.
Example:
• Total weight of 10 empty capsules = 750 mg
Average Capsule Weight = Total Weight / 10
Average Capsule Weight = 750 mg / 10 = 75 mg
Step 5: Calculate the Total Weight of a Filled Capsule
Once you know the fill weight and the average weight of the empty capsule, you can calculate the total weight of the filled capsule.
Formula:
Filled Capsule Weight = Fill Weight + Average Empty Capsule Weight
Example:
• Fill Weight = 400 mg (from Step 2)
• Average Empty Capsule Weight = 75 mg (from Step 4)
Filled Capsule Weight = 400 mg + 75 mg = 475 mg
Step 6: Geometric Dilution for Blending
To ensure uniform distribution of the active drug in each capsule, use geometric dilution when mixing the drug with the filler.
Process:
1. Start with organic dye powder or Pharma dye. (Subtract amount from filler volume/weight)
2. Mix a small, equal amount of the active drug and filler together.
3. Gradually add more filler in small increments, blending thoroughly after each addition.
4. Continue until all of the filler is mixed in.
This method ensures that the drug is evenly distributed throughout the mixture, which is crucial for consistent dosing.
Step 7: Volume-to-Weight Conversion (if needed)
If you need to convert the weight of the powder to volume or vice versa, use the following formula based on the bulk density.
Formula:
Volume (mL) = Weight (mg) / Bulk Density (mg/mL)
Example:
If you have 100 mg of the drug and its bulk density is 0.8 g/mL (800 mg/mL):
Volume = 100 mg / 800 mg/mL = 0.125 mL
This means the drug will occupy 0.125 mL of the 0.50 mL total capsule volume, with the rest filled by the inert filler.
Example Calculation for Filling Size 1 Capsules
Let’s say you’re making size 1 capsules that need 50 mg of active drug per capsule, with lactose as a filler. The bulk density of lactose is 0.8 g/mL.
1. Calculate Total Fill Weight:
Fill Weight = 800 mg/mL * 0.50 mL = 400 mg
2. Calculate Filler Weight:
Filler Weight = 400 mg - 50 mg = 350 mg
3. Weigh Empty Capsules:
• Total weight of 10 capsules = 750 mg
• Average Capsule Weight = 750 mg / 10 = 75 mg
4. Calculate Filled Capsule Weight:
Filled Capsule Weight = 400 mg + 75 mg = 475 mg
**IMPORTANT FOR USING CAPSULE MAKERS**
To scale your formula for filling 100 capsules, you can use simple proportion math.
Step 1: Calculate the total amount of drug and filler for 1 capsule
• If each capsule contains 50 mg of drug and 350 mg of filler, the total fill weight is 400 mg per capsule.
Step 2: Scale to 100 capsules using proportion
To scale up for 100 capsules, simply multiply the amount for 1 capsule by 100.
Formulas:
1. Drug amount for 100 capsules:
Drug for 100 capsules = Drug per capsule * 100
Example: 50 mg * 100 = 5000 mg (or 5 g)
2. Filler amount for 100 capsules:
Filler for 100 capsules = Filler per capsule * 100
Example: 350 mg * 100 = 35000 mg (or 35 g)
3. Total mixture amount for 100 capsules:
Total mixture for 100 capsules = Total fill weight per capsule * 100
Example: 400 mg * 100 = 40000 mg (or 40 g)
Step 3: Adjust for losses (Optional)
It’s a common practice to prepare extra powder (e.g., for 2 additional capsules) to account for losses during filling.
Formula to adjust for losses:
Total for 102 capsules = Total fill weight per capsule * 102
Example: 400 mg * 102 = 40800 mg (or 40.8 g)
By using these formulas, you can scale any formula to larger batch sizes as needed.
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