Alligation Method for Mixing Ointments
The following example illustrates the use of Alligation method in obtaining desired strength of an oitnment using ointments of two different strengths.
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Solved Problem: In what proportion should 20 % benzocaine ointment be mixed with an ointment base to produce a 2.5 % benzocaine ointment? Approach: Set up a tic-tac-toe grid which includes the higher, lower (in this case 0% as the ointment base has no drug content) and desired strengths. 
Answer: 17.5 parts of ointment base should be mixed with 2.5 parts of 20 % benzocaine ointment to produce 2.5 % benzocaine ointment. |