![]() ![]() In total, there are 4,500mg of drug within the 187.5mL of medicine. In other words, every 5mL of the 187.5mL contains 120mg of drug. 37.5 doses x 5mL = 187.5mL of solution must be dispensed.Therefore, if we divide 4,500mg by 120mg, we can establish how many doses the patient needs: As we already learned, each 5mL of solution contains 120mg. So, the patient requires 4,500mg and the concentration of the solution is 120mg/5mL. 4.5 grams is the same as 4,500mg (always multiply by 1,000).However, the patient requires 4.5 grams of drug. In this case, the concentration of drug is 120mg/5mL. Remember our earlier rule – always identify inconsistent units. The question asked us how many milliliters of medicine we need to prescribe to the patient if they require 4.5 grams of drug. In a matter of minutes – not hours – you will begin to see real progress. It takes practice, but always try to sit down with a pen and paper and practice these kinds of conversions. The numbers are flexible if you know how to use them. So, understanding concentrations is important. Therefore, we can re-write the concentration as 2.4% w/v solution. If there are 24mg in 1mL, then there must be 2,400mg in 100mL of solution.We are simply dividing both sides by 5 to determine how many milligrams of drug is in each mL. 120mg per 5mL is exactly the same as 24mg per 1mL.Of course, we can innocently play around with the numbers, too. If the 120mg is a drug, then the patient is receiving that much drug in each teaspoon. In other words, if we have 100mL of the solution, every 5mL teaspoon of that solution will contain 120mg. In the question above, we are given a concentration of 120mg/5mL. This question does not use these expressions, but it is important for pharmacy technicians to be both familiar and comfortable with them and how to interpret them in any given PTCB math question. What matters is the weight of the substances itself. In this case, it does not matter that it may be two liquids. 8% w/w concentration = 8 grams per 100 grams of medicine.In this case, the concentration of hydrochloric acid is 50% v/v. 2.5% v/v concentration = 2.5 mL per 100mL of solutionįor example: if you add 50mL of hydrochloric acid to 50mL of water, you have created a total of 100mL volume per volume (v/v) solution.In this case, if we add 1 gram of sodium chloride and make the solution up to 100mL with sterile water, we have created a 1% sodium chloride w/v solution. 5% w/v concentration = 5 grams of drug per 100mL of solution.But by practicing as many PTCB questions as possible, you begin to become ever more fluent in this mathematical language. Initially, it may seem an alien or even difficult language to speak. ![]() You will come across many PTCB practice math questions that deal with these kinds of concentration problems. It is important for pharmacy technicians to become comfortable with drug concentrations. If a solution contains a concentration of 120mg/5mL, how many milliliters should be prescribed to the patient if they require 4.5 grams of drug? There is 5,600mg of talc in the 140 grams of compounded medicine. However, the answers are provided in milligrams – so we need to multiple 5.6 grams by 1,000: 4 percent of the formulation is talc therefore, we need to multiply 4% by 140 grams to establish how much talc is present. We are told to create 140 grams of medicine and asked to find how much talc will be present in this medicine. It also helps examiners fish out candidates who understand the nature of the question and how to find the answer. Often, this is intentional – to create distractions. Many PTCB practice test questions will contain information or details that you do not need to use. Second, students should always identify the information they need to use in a question. This is important, and we will come back to it soon. In this case, we are told to compound 140 grams of medicine, but the answers are listed in milligrams. To understand how to answer these kinds of PTCB practice math questions, we must comprehend a few fundamental points.įirst, always notice discrepancies with units. How much talc is required to compound this medicine? You are required to make 140 grams of medicine with the following formula: ![]()
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