Worked example of displacement value Prepare eight suppositories (1g each), each containing 200 mg bismuth subgallate: For eight suppositories, 0.2gtimes 8=1.6g drug. The displacement value for bismuth subgallate is 3.0 g. Three grams of drug displaces 1 g base;therefore 1.6 g drug displaces (1.6/3) 0.53 g base. The amount of base required for eight medicated suppositories is 8g-0.53g=7.47g EXAMPLE. You receive a prescription for ten morphine sulfate 10 mg suppositories. You decide to prepare 12 suppositories to allow for any losses during preparation, using theobroma oil as the base. How many grams of theobroma oil are required to prepare 12 suppositories, each ontaining morphine sulfate 10 mg sufficient to fill a 2 g mould? The displacement value for morphine sulfate in theobroma oil is 1.6. Give your answer to 2 decimal places 1) Amount of morphine sulfate required for 12 suppositories=10mgtimes 12=120mg=0.12g 2) Amount of base required to prepare 12 unmedicated 2g suppositories=2gtimes 12=24g 3) As the displacement value for morphine sulfate is 1.6, this means that 1.6 g will displace 1g of base, so by simple proportion: Morphine sulfate (g) 1.6 12.12 ?=(1times 0.12)/(1.6)=0.075g Theobroma Oil (g) 1 ? =gt 0.12g of morphine sulfate will displace 0.075 g of base 4) Therefore the amount of base for 12 medicated suppositories=24-0.075=23.925g Answer=23.93grams to 2 decimal places

To solve this problem, we need to calculate the amount of theobroma oil required for 12 medicated suppositories, each containing 10 mg of morphine sulfate. Let's go through the steps:<br /><br />1. **Calculate the total amount of morphine sulfate needed:**<br /><br /> \[<br /> \text{Amount of morphine sulfate} = 10 \, \text{mg/suppository} \times 12 \, \text{suppositories} = 120 \, \text{mg} = 0.12 \, \text{g}<br /> \]<br /><br />2. **Calculate the total amount of base required for 12 unmedicated suppositories:**<br /><br /> \[<br /> \text{Base required for unmedicated suppositories} = 2 \, \text{g/suppository} \times 12 \, \text{suppositories} = 24 \, \text{g}<br /> \]<br /><br />3. **Determine how much base is displaced by the morphine sulfate:**<br /><br /> The displacement value for morphine sulfate is 1.6, meaning 1.6 g of morphine sulfate displaces 1 g of base. Therefore, 0.12 g of morphine sulfate will displace:<br /><br /> \[<br /> \text{Displaced base} = \frac{0.12 \, \text{g}}{1.6} = 0.075 \, \text{g}<br /> \]<br /><br />4. **Calculate the amount of base required for the medicated suppositories:**<br /><br /> \[<br /> \text{Base required for medicated suppositories} = 24 \, \text{g} - 0.075 \, \text{g} = 23.925 \, \text{g}<br /> \]<br /><br />5. **Round the answer to two decimal places:**<br /><br /> \[<br /> \text{Final answer} = 23.93 \, \text{grams}<br /> \]<br /><br />Therefore, you will need 23.93 grams of theobroma oil to prepare 12 medicated suppositories.