The Pharmaceutics and Compounding Laboratory
Intranasal Preparations

Calibration of Dropper or Spray Bottle

Generally, intranasal solutions and suspensions are administered as drops; solutions can also be administered as a fine mist from a nasal spray bottle. Nasal sprays are preferred to drops because drops are more likely to drain into the back of the mouth and throat and be swallowed.

If drops or sprays are used, the quantity of drug administered in each drop or each spray should be calibrated.

To calibrate a dropper:

  • drop the formulation into a small graduated cylinder (5 mL or 10 mL) using the dropper the patient will use
  • count the number of drops required to dispense 3 ml of solution
  • divide the number of drops by 3; this will give the number of drops per mL
  • calculate the number of drops needed to dispense the volume of formulation in one dose

To calibrate a spray bottle:

  • prime the spray bottle
  • weigh the spray bottle when filled with the formulation
  • deliver 10 sprays into a plastic bag
  • re-weigh the spray bottle
  • divide the difference in the two weights by 10; this will give an average volume delivered with each spray
  • calculate the number of sprays needed to dispense the volume of formulation in one dose (assume specific gravity = 1)

Keep in mind that the patient's manner of squeezing the spray bottle may be different. The pharmacist should have the patient calibrate the spray bottle to provide more accurate dosing.