Skip to main content

Laboratory Procedure

A. Manual Filling of Hard Gelatin Capsules

Compound, label, and dispense the following prescription: (PREPARE 12 CAPSULES – Dispense seven (7) capsules and save five (5) capsules for analysis. Calculate for 14 capsules.)

                 The University of North Carolina     Rx# 61701
                        School of Pharmacy
                          Chapel Hill, NC
Phone:  555-1234                                 DEA# PS0079411

Name:   June B. Ride                            Date:  Today 
Address: Sendabills Drive, Chapel Hill NC 27599 Phone: 916-6777


Salicylic Acid 4 mg Lactose q.s. 350 mg

M. Ft. D.T.D. caps #12

Sig: 1 cap q AM x 2 d, then return to clinic

No refill


Able Andredy,M.D.                                                            ________________

Product selection permitted                                               Dispense as written


Amount of Salicylic Acid Needed for 14 Capsules _________

Preparation of trituration
Make the necessary calculations and describe how the trituration will be prepared.

Salicylic Acid ____________ mg
Lactose ____________ mg
Total Weight of Trituration ____________ mg


Give the compounding formula

Total Amount of Trituration Needed to Prepare 14 Capsules (i.e., your chosen aliquot size) _____________ mg
Total Amount of Lactose Needed to Make 14 Capsules of Desirable Weight _____________ mg
Total Weight of 14 Capsules _____________ mg
Capsule Size Needed _____________

Describe the compounding procedure

 View a video demonstration on capsule punching

Inspection of Final Preparation ___________________


B. Evaluation of Capsules

NOTE: Capsule contents should be analyzed in the same order as weighed in the weight variation test so that a comparison between weight variation and content uniformity can be made.

1. Weight Variation

  1. Using the balance, weigh each capsule, taking care to preserve the identity of each.

  2. Empty the contents of each capsule into a flask and weigh the empty capsule shell. Determine the weight of the contents of each capsule.

  3. Calculate the following for the “% of Intended Weight”:
    • the mean
    • standard deviation
    • relative standard deviation
Capsule # Weight of Finished Capsule Weight of Empty Capsule Weight of Contents % of Intended Weight
mean = ________
standard deviation = _______
relative standard deviation = _________


2. Content Uniformity

  1. To each flask containing the contents of one capsule, add 100 ml of 0.01 N NaOH. Prepare a blank of 0.01 N NaOH.

    Using a set of reference standards of known concentration, prepare a Beer’s Law plot. Read the absorbance of each standard and sample at 310 nm using the spectrophotometer. Using the slope and intercept of the Beer’s Law plot to convert absorbance to concentration, calculate the weight of active ingredient in each capsule.

  2. Calculate the following for the “% of Labelled Claim”:
    • the mean
    • standard deviation
    • relative standard deviation
  3. Prepare a Beer’s Law plot of the following salicylic acid standards. Attach graph.
Salicylic Acid Absorbance @ 310 nm Regression Analysis
0.00 mg/ml __________________ intercept = _________
0.02 mg/ml __________________  
0.04 mg/ml __________________ slope = ____________
0.06 mg/ml __________________  
0.08 mg/ml __________________ R2 = ______________
0.10 mg/ml __________________  


Capsule # Absorbance Concentration Amount in Capsule (mg) % of Labelled Claim
mean = ________
standard deviation = _______
relative standard deviation = _________


C. Discussion

  1. During commercial preparation, which “Uniformity of Dosage Units” test would be applied to the capsules you prepared, weight variation or content uniformity? Explain.

  2. The USP24/NF19 requires that extemporaneous prepared capsules be 90% – 110% of the theoretical weight. Do your capsules meet these standards in terms of the “% of Intended Weight”?

  3. Is there a correlation between weight variation and content uniformity in the capsules you prepared? How did you determine if a correlation existed? How would you account for variations from the expected correlation?