PHR2021: Workshop 1

Solutions

PHR2021: Workshop 1

Question 1 (Paracetamol suppository)

Max base needed for 12 supp's with 30 mg paracetamol:

Weight of base + paracetamol in all suppositories:

PHR2021: Workshop 1

Using we can deduce (5% glycerol):


Finally, we can now calculate the weight of base needed:

PHR2021: Workshop 1

We know that the mould is calibrated to 1 g. The mass of the base

  • Paracetamol (): (30 mg per supp, )
  • Glycerol (): 5% (w/w) of the final suppository ()
  • Massuppol (): as needed, assume the mould is calibrated to 1g.

Each supp. :

  • of ,
  • of (5%) and
  • is just remainder
PHR2021: Workshop 1

When we apply the DVs:

  • of displaces of base, i.e., of displaces .
  • of displaces of base.

That is, the required is per supp.

For 12 suppositories, the total mass of base needed is:

PHR2021: Workshop 1

Question 2 (Miconazole suppository)

Each supp contains 400 mg miconazole. Given the density of miconazole is 1.5, the volume is:

The mould was calibrated with hard fat, holding 0.94 g per cavity. Assuming density of 1.0, the mould cavity volume is:

PHR2021: Workshop 1

The drug will occupy part of the cavity, so the volume available for the PEG base is:

Now we convert PEG volume to mass, given that the density of PEG is 1.2, the total mass of PEG needed is:

Given the 1:4 ratio (5 parts total), we can deduce how much of each PEG is needed:

PHR2021: Workshop 1

Question 3 (Anticancer drug dose)

We first deduce the BSA of the patient:

Using the calculated BSA, the total dose is:

PHR2021: Workshop 1

Question 4 (The stoichimetry bag)

How much of each ion do we need in total? We can deduce this from the final mole of each ion in the 5 L bag (i.e. conc ):

Ion Conc. (mM) (mmol)
145 725
0.5 2.5
35 175
2 10
PHR2021: Workshop 1
  • and

Recall that we have (8.4% w/v) ampoules . Also recall that the MW of is .

The proprietary bag initially has:

meaning we need this much extra sodium:

PHR2021: Workshop 1

That is, per mL we have of , (By dividing by )

1 mmol of weighs ,

We can infer that every mL of the ampoules provides 1 mmol of and .


Since , we need of the ampoule.

Also adds of , which is exactly what we needed!

PHR2021: Workshop 1

We need 2.5 mmol of and we have (1 mmol/L) ampoules. We simply need 2.5 mL of the ampoule. Note that this also adds of .

PHR2021: Workshop 1
  • : Need of , and we already added from the ampoule. We need to make up the remaining from (2.45 g in 5 mL).
    • MW()
    • How much mmol in 5 mL?

Since we need , we just need of the .


Overall, of , of , and of .

PHR2021: Workshop 1

Question 5 (Buffer I)

First, we calculate the moles of weak acid. Given the 0.6% w/v solution, the mass of acid in 10 mL is:

Given the MW of acid is about 60, the is:

PHR2021: Workshop 1

Then, we calculate the moles of the salt of the weak acid.
The 1.36% solution contains 1.36 g salt per 100 mL. The mass of salt in 50 mL is:

Given the MW of the salt is 136.1, the is:

PHR2021: Workshop 1

We can now solve for pH using the Henderson-Hasselbalch equation:

PHR2021: Workshop 1

Question 6 (Buffer II)

First, we calculate the moles of weak acid. Given the 1% w/v solution, the mass of acid in 10 mL is:

Given the MW of acid is about 192.2, the is:

PHR2021: Workshop 1

Then, we calculate the moles of the salt of the weak acid. A 1.5% solution contains 1.5 g salt per 100 mL. The mass of salt in 40 mL is:

Given the MW of the salt is 294.1, the is:

PHR2021: Workshop 1

We can now solve for pH using the Henderson-Hasselbalch equation:

PHR2021: Workshop 1

Question 7 (Calamine)

A 0.5% w/v solution means 0.5 g of phenol per 100 mL of calamine lotion APF. For 5 L, we need:

Liquefied phenol BP contains 80% w/w phenol. Let be the mass of liquefied phenol BP needed. Then:

PHR2021: Workshop 1

Given the density of liquefied phenol BP is 1.057 g/mL, the volume of liquefied phenol BP needed, , is:

PHR2021: Workshop 1

Question 8 (Antiarrythmic formulation)

First we determine the mass of the antiarrythmic required, , for 50 mL of formulation:

Now we can solve for the volume of the ampoule needed. Given that it contains 1.2 mg/mL and we need 0.6 mg:

Therefore, we need 0.5 mL of the ampoule to dispense 50 mL of the mixture.

1. Calculate the amount of massupol base required for following formulation: Paracetamol 30 mg (DV = 1.6) Glycerol 5% (DV = 2.0) Massuppol q.s. Please prepare 12 suppositories. (Assume the calibration of the mould is 1 g) Density of massuppol is 1 g/mL

original answer

second attempt

2. Calculate the amount of PEGs (Macrogol Base) required to prepare 25 * 1 g suppositories of miconazole (DV = 1.5) 400 mg. DATA: The density of PEG Base = 1.2 g/mL. PEG Base consists of PEG 300, 1 part and PEG 4000, 4 parts by weight. The mould was calibrated with Hard Fat and found to hold 0.94 g Hard Fat per cavity.

3. An anticancer drug may be used as a single agent or in combination therapy via IV infusion at a dose of 20 mg/m2 daily for 5 days (5 days = 1 course). The following equation by DuBois & DuBois is often used to calculate BSA: BSA (cm2) = weight (kg)0.425 * height (cm)0.725 * 71.8410 What is the total dose of anticancer drug that a 63 year old patient receives if they weigh 81 kg, are 171 cm tall, and receive one course of therapy?

4. You are the pharmacist on the renal ward hospital. You are required to supply a haemofiltration bag of approximately 5 litres for one of your patients. The bag must contain a total of 145 mmol/L Na+, 0.5 mmol/L H2PO4-, 35 mmol/L HCO3- and 2 mmol/L K+, but may contain other ingredients. The amount of acetate added to the bag is unimportant.

thus each mL of the ampoule contains $\frac{0.0841\mathrm{g}}{84.1\mathrm{g\mkern2mumol^{-1}}} \approx 1\mathrm{mmol}$ of $\mathrm{NaHCO_3}$.

5. What will the final pH be of a buffer solution made by mixing 10 mL of 0.6% weak acid (MW = 60.05; pKa = 4.8) with 50 mL of a 1.36% Sodium Acetate (MW = 136.1) solution?

What is the final pH of a buffer solution made by mixing 10.0 mL of a weak acid (pKa = 6.4) and 40.0 mL of a 1.5% solution of sodium salt of the weak acid (294.1)?

The local hospital asks you to prepare 5 litres of Calamine Lotion with an EXTRA 0.5% w/v Phenol to increase its antipruritic activity. How much Liquefied Phenol BP would you require if you were making the formulation? DATA: Calamine Lotion already contains 0.5% w/v of Liquefied Phenol Liquefied Phenol BP contains 80% w/w Phenol in Water. It has a density of 1.057 g/mL

A formulation used commonly used in hospitals contains: Antiarrythmic 60 micrograms Syrup 0.6 mL Purified water to 5 mL What volume of an ampoule containing 1.2mg of the antiarrhythmic per mL would be required to dispense 50mL of the mixture?