PTCB Pharmacy Calculations #2
What is the percent of hydrocortisone in the final combination if 60 gm of 1% hydrocortisone is mixed with 80 gm of 2.5 % hydrocortisone?
Hydrocortisone concentration in 60 gm: 1%
Hydrocortisone (60/100) = 0.6 gram
2.5 percent hydrocortisone content in 80 gram
2 gm hydrocortisone = 80 x 2.5/100
the amount of hydrocortisone in the final combination as a percentage
= 100 x 2.6 (2gm + 0.6gm)/140 (80gm + 60gm)
= 1.85% w/w.
How much sodium bicarbonate powder is needed to make 240cc of sodium bicarbonate solution at 0.10 N?
Normality is defined as the number of gram equivalent weights of solute in one liter of solution, therefore a 1N solution of sodium bicarbonate will contain 84 gms in 1000 cc. We need to know how much sodium bicarbonate is in a 240cc, 0.1 N solution:
1 N solution contains 84 gm
0.1 N solution contains ?
= 0.1 x 84 = 8.4 gms/1000cc.
240cc solution will contain:
= 240 x 8.4/1000 = 2.016 gm of NaHCO3
To make a 30 percent of 500cc alcohol solution, how many cc of 75 percent alcohol should be mixed with 10% of 1000cc alcohol?
To solve this type of problem, we need to use alligation method.
75 20 (75%)
10 45 (10%)
Total parts 65 (30%)
To prepare 65 (30%) 20 parts (75%) need
To prepare 500 (30%) ?
= 500 x 20/65 = 153.84cc (75%) alcohol
If we mixed 153.84 cc of 75% alcohol with 346.16cc [500cc - 153.84] of 10% alcohol, then we can get 500cc of 30% alcohol solution.
In a 0.9 percent 250cc normal saline solution, how many meq of Na+ are present? [Na+ = 23, Cl- = 35.5]
In 250 cc of 0.9 percent NaCl, there is a certain amount of sodium chloride.
2.25 gram NaCl = 250 x 0.9/100
Na+ = weight in grams = total equivalents
0.03846 equivalents = 2.25/58.5
What would the retail price of 30 Risperdal 1 mg tablets be if 1000 tablets cost $ 2250 and the percent markup on prescription is 20%?
Risperdal 1mg tablets cost $ 2250 for 1000 tablets. The percentage markup on prescriptions is 20%.
As a result, the retail price of 1000 tablets would be as follows:
** For each $ 100 cost = $120 retail cost** = 120 x 2250/100 = $ 2700
The cost of 30 tablets would be:
$ 81 = 30 x 2700/1000
What is the dose of a drug in cc for a 15-month-old infant if the dropper is calibrated to give 325 mg of iron sulfate in 0.6 cc and the adult dose of the drug is 325 mg?
0.06cc. Fried's rule is as follows:
12 months of age multiplied by 150 x adult dose
32.5 mg = 15 x 325/150
Because the dropper is calibrated to give 325 mg of Iron sulfate in 0.6 cc:
0.06cc = 0.6 x 32.5/325
How much atropine is needed to make 240cc so that 1 teaspoonful of the solution diluted to 1 pint yields a 1 in 500 solution?
To address a situation like this, we must first determine the amount of medication contained in the final solution.
1 pint of atropine contains 1 in 500 soln of atropine.
0.96 gm atropine = 480 x 1 /500
Because 0.96 grams of drug must be present in 1 teaspoonful of drug solution, we can conclude:
0.96 gram in 5cc (1 teaspoonful).
240cc solution requires
= 240 x 0.96/5 = 46.08 gm of atropine.
What is the PH of the solution if the ratio of ionized to unionized drug species is 103 and PKa = 2.2?
The following formula can be used to determine the pH of a solution:
pH = log ionize/unionize + pKa
= log 103 + 2.2
= 2.2 + 3
What is the likelihood of failure if the probability of success in the Null hypothesis is 0.6?
In the Null hypothesis, the total of the probabilities of success and failure equals 1 and can be represented using the following formula:
p + q = 1, where p is the chance of success and q is the probability of failure.
q = probability of failure
q = 1 - p
= 1- 0.6
How many 250 mg/100cc ready infusion-bags are required to satisfy the above request if the drug's dose is 10 mg/kg/day? The patient is 156 pounds.
Because the patient's weight is 156 pounds, the weight in kilograms is 156/2.2 = 70.9 kilograms.
A usual medically recommended dose of medication is 10mg/kg/day, hence the dose in the patient mentioned above is 10mg/kg/day.
= 10 x 70.9
= 709 mg
Because each ready-infusion-bag contains 250 mg of medication, the total number of bags needed to satisfy an order is:
= 709/250 = 2.83 = 3 bags.
How much cocabutter is needed to distribute 12 tannic acid suppositories, each weighing 2 gm and containing 400 mg of tannic acid?
We'd like to give out 12 suppositories, each weighing 2 grams and containing 400 milligrams of tannic acid:
Amount of coca butter = 2 gm x 12
= 24 gm
Amount of tannic acid = 0.4 gm x 12
= 4.8 gm.
Tannic acid has a displacement value of 0.9, so:
= 4.8/0.9 = 5.33 gm of base will displace
4.8 gm tannic acid = 5.33 gm cocabutter
Coca butter quantity = 24 gram - 5.33 gm
= 18.67 gm