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Yeah, so Hi, everyone. Welcome to the fourth session of our PAS a series. Today we have Doctor, some men who are on who will be delivering a session on drug calculations. If you guys do have any questions, please feel free to write them in the chat. Um, and also, there will be a feedback for me at the end, so it will be much appreciated if you could fill that out. So over to Doctor. Hi, guys. I'm Syngman. I'm an F one at the rule. Sorry at the moment. And, yeah, I graduated from Imperial this year, so I'll just give you a quick talk on P s, A. The calculation section. So, um, the contents of this lecture is going to be quite straightforward, so I'll just briefly walk you through the calculation section and go through a few practice questions. So if you do have any questions, do you pop it in the chat? And I think they'll let me know. Cool. So the calculation section has eight questions each worth two marks, So that will be 60 marks in total. And you do get a calculator on the screen of your question. So you can use that. Or I think some people did bring in their own calculator. So as long as it's not a scientific calculator, you can bring in, um, and the questions of the calculation section. They often provide you more information than you need, so don't get stressed about not using all the information that's on the screen. So the types of questions. So I've tried to classify into three different sections. Not all questions will go under these brackets, but majority, I think. Well, so those calculations for prescriptions. So that's when we're adjusting for the patient's age, weight, surface area. And also they sometimes to ask you about the number of tablets that they need as well. And concentration calculation, which I'll talk about in the next few slides and also infusion. Right calculations. Sorry something. There's a question already. Does Imperial allow you to bring your own calculate into the exam? Yeah, yeah, they did. They did. And you also get a piece of paper as well too, right? You're working out as well. But just make sure your calculator isn't one of those scientific ones you don't need. The scientific calculators just do like multiplications and divisions. So yeah, but they do. And yes, so concentration. So that's when the question asked you about 1, 200 or 1%. So obviously, I hope you guys all know that concentration is massive, solid over volume of solution. But this is just a recap, and I put the brackets in. So if it's in percentages, you want to multiply that by that, multiply that by 100. But if not, you don't need to. And the default for these one in 100 or like 1% concentrations are that it's grams in milliliters. So when it says, for example, one in 100 that's 1 g in 100 mL, that's the same for 1%. So that's 1 g in 100 mL, and the grave, it's I've just simplified it so we know what the what it is in per milliliter. So the great but you can do while you're working out in the actual exam. But I think it's just useful to know that one in 100 is the same as 1% which is 1 g in 100 millimeters. So that's the same with one in 1000 which is 1 g and 1000 mL, which is not being upset. And one in 10,000, which is one in one ground and 10,000 millimeters. It's not quite not 1% it makes sense. Just remember, default is grams in milliliters, and they often get you to convert units. So make sure you check what unit you want to arrive at. So what are they asking you for If they're asking you for micro grams and make sure you work towards getting to the micro grams, Um, and I know you're conversions, So I've seen in the Mach test, um, they did ask about nanograms, which is 10 to the minus 9 g. So it'll just be multiplied by 1000 from micrograms, which will get you to nanograms. But otherwise, yeah, it's just your normal convergence from Kilogram's two micrograms. And, um, sometimes I find that it's easier to keep your units in your calculations. So, for example, if a question like this comes up, so how much morphine is 20 mils of or more in or above 10 mg per five millimeters? And they wanted to calculate the dose in milligrams. So so the mass is concentration of times volume and the concentration would be 10 mg over 5 mL times 20 mL. So having written units in your calculation, you can just cancel out the units. So you know that you've arrived at 40 mg rather than going through millimeters altogether. I have some sense, and also they make you come back mils per hour two mils per minute milligrams per hour milligrams per minute. And that's just from our two minutes. You want to divide by 60 and for minutes to hours you want to multiply by 60. And that's just another thing that you just want to know. I guess so this is about opioids. So if you go on the n f and you type in the opioids, I'll actually show you because it's like it's easier to show you. So I've typed in opium or opioid being. If the first thing that comes up is prescribing palliative care, you want to click on that. And if you just scroll down to the very first table you get here we go. So if we have a look, so morphine oral morphine, it's 10 mg and you just look at how it converts to other types of opioids and just be aware of oral moving is different. I n i v subculture movie. And if you scroll down further, it gives you the conversion table for buprenorphine patches, fentanyl patches. Um, at the very end of the page. There's also subcut infusion morphine. It was 24 hours, if that is what you need to be looking at. So it's just so opioid conversion tables, you can find them in the TNF so you don't need to memorize them. Yeah, so that's on the palliative care. And, yeah, cool. So I'm going to go on to practice questions Do. Are there any other further questions on the chat? Not at the moment. No. Um so, yeah, I've said one minute and some questions might need a bit more so, But the first few questions I think you can do it in one minute. So first we'll go through some of those calculations. So just be aware of units. Be aware of the duration of the course of the drug and concentrations as well, so I won't read the questions at all. You can just read it to yourselves and try half ago. So there we go. I'll time. One minute, 10 seconds left. Cool. So the answer for this one is 1.8 millimeters. So how did we arrive? So for the solutions, I've written out basically every single step. So you obviously don't need to go through all these steps. Some of them I'm sure you can do in your head. But just for reference when you want to look back at these slides have just written out. So they've given you the weight and they've given you the dose per kilogram every 12 hours. So for one dose it would be 3.6 times 25 mg. So the 90 mg because they wanted the volume over 12 hours. So, uh, sorry for 24 hours. So over 24 hours he would need 180 mg. And now we want to convert that into millimeters. So they've given you that it's going to be 600 mg in six millimeters, so 100 and 80 mg would be 1.8 millimeters. I think that was a straightforward one. And then the next one as well. Another one minute, 10 seconds time. So the answer would be 42 tablets. So again, um, after time is 1.5 by 20 like the last one with the kilograms. So for one day it'll be 30 mg. And because it comes in 5 mg tablets, you get 6 mg tablet. Well, 65 mg tablets for one day, but they've asked for one week supply. So you want two times that by seven. So you get 42. Yeah. Next question. Another minute. 10 seconds. That's time. So you would need 30 miles. So again, this is body surface area, so those would be 500 mg times 19.4 m squared. That's 200 mg, and you need that TDs for 10 days. However, because the acyclovir comes in 250 mg vials and you can't reuse the vials so you can't reuse the 50 mg that's left over. It would be one vial for each dose, so you use one vial TDs for 30 days, which gives you 30 vials. Who and then the next question, Another minute. That's this is your final dose calculation. Question this one. I'll give you 15 seconds more because you need to look at the TNF 10 seconds. Um, time. So the answer would be the fentanyl 50 patch. So this one is so you need to use your morphine, not morphine. Sorry, Period. Conversion table on the other table. So the solution would be So you look at the regular goes first. Well, I have. That's the normal 30 mg B d. So that's 60 mg of morphine per day, and then the p R N does is 10 millimeters of more and more, which comes in 10 mg per 5 mL. So that means for 10 millimeters there's going to be 12 20 mg of morphine. And because this person is using it three times a day, so the total PRN dose would be 20 times three. That's 60 mg per day. So overall, in one day, the total dose of morphine would be 120 mg. So because we want to come back to the fentanyl patch, we, um I looked up the TNF the conversion table, so it's very small, So morphine salt 120 mg daily is equivalent to the fentanyl 50 patch. So that's how I got the 50 patch. So yeah, so I just wanted to clarify before we move on to the next section. So no more. And mst they are both modified or slow release tablets of morphine and they are just equivalent to the normal morphine sulfate you get. So if you look at the active ingredients, zero more 10 mg is equal to morphine sulfate, 10 mg and M S T 5 mg is equal to morphine sulfate. 5 mg. I just got this on the TNF. The medicine forms. So yeah, they've been cool before. I move on to the concentration calculation questions. Were there any questions from the previous for questions? Yeah. One question is, could you please explain how you got 30 acyclovir but files again? Yeah. So, um, I don't know whether that's part of it. Um, but, uh, confused. But so the dose for the actual a cycle, there would be 200 mg because we're multiplying 500 by 9.4. So that's 200 mg. And because the acyclovir vials only come in 250 mg miles, apparently, and you can't reuse the left over 5 50 mg for the next dose. So it says, given that acyclovir must be used immediately after reconstitution. So as soon as you open the vial, you need to use it before that dose. So that means although it comes in 250 miles, you need to use one vial per dose. So what? How am I making sense? So 200 mg is the actual dose you're giving, But the vial you're using? One vial for that dose. And because we're using it three times per day for 10 days, One vial, three times a day for 10 days with the 30 miles it doesn't make sense. The past, um, reply if they need. She said, Yeah, yeah. All right. Thank you very much. Cool. So the next question would be on concentration calculation, so just another reminder that the default is grams in milliliters one. So, for example, 1% would be one in 100. Um, and that's one round in the 100 mL. Cool. So, yeah, Another one minute for these questions. So off you go. Sorry. The maximum dose allowed is 200 mg 10 seconds time. Do you let me know if I'm going too fast or too slow in terms of the timing of the questions? So the answer would be eight millimeters. So again, yeah, 1% is 1 g, uh, 100 mils. So if we cancel it down, that's 10 mg per milliliter. So in 12 millimeters of lidocaine, that would give us 100 and 20 mg of lidocaine that's already been administered because it's asking how much more can be given. Under the maximum dose is 200 mg. We can find out that we have 18 more, 80 mg more that we can give. And again they wanted in milliliters. So we need to come back two millimeters. So that's eight millimeters. Yeah, and then, yeah, the next question I'll give you another minute. 10 seconds time. The answer would be 65 micrograms. I'm sorry, I've I've abbreviated it to M. C. G. But you actually have to write micrograms out in full. Sorry. Um, so let's go through the calculations. So one and 200,000. So if you cancel that down, you get 1 mg in 200 mL and because they wanted it in microgram. So I'm going to come back in two micrograms and then cancel that down further. So you get five micrograms per minute eater and because the total of 13 millimeters has been injected. So you're just times five by 13 and you get 65 micrograms and you remember to write down the micro grams in pool and then the final calculations questions. I think I'll give you another minute, 10 sacraments time. So the volume of the look so you should be given is 2.5 millimeters. So we're yeah, mental note that we're dealing with volumes and millimeters and they've given us 5 50 micrograms per minute, but not 500.125 mg. I'm just going to convert that to micrograms. So that's 225 micrograms per day. And because of the strength of digoxin, is that just gonna do some calculations? So volume equals mass of concentration, So volume would be 100 and 25/50 and that would be 2.5 mL and yeah, so that would bring us to the next section. Any questions on the chat? Yeah, there's one. Would we have to write milliliters in full or just ml know milliliters? Yeah, you can write ML. It's just a micro grams because, yeah, I didn't write that cool. So the rate calculations again, you need to know the fact that it's crammed the milliliters and just be careful with your power to permanent permanent power conversions. Cool. So these ones tend to take a little bit longer, so I'll give you about 10 seconds more. So about 70 seconds, 10 more seconds. I'm tired, so the rate would be 100 and 25 millimeters per hour. So we have those of digoxin 0.75 mg of, uh, four hours, so 9.75 mg would be 750 micrograms. I've changed into micrograms because the concentration is given as micrograms per milliliter. So concentration equals mass in the volume again. And I just substituted in those values to find out the volume of the digoxin and the volume would be, if you re cancel about, it would be 500 mL. But because it's 500 millimeters over the four hours, we need to divide that further to find a millimeter hour, which would be 100 and 25 millimeters power. Yeah, cool. So the next question another 70 ish seconds, 10 seconds and time, so the answer would be 62.5 micrograms per kilogram per minute. So for this question, obviously we need to take note that that's our final unit. And so the drug has a concentration of 250 mg and 5 mL, but the per hour there's six millimeters of the drug being administered. So in six millimeters, that's going to be 300 mg according to the concentration. And that's 300 mg per hour, which, if we convert the palate per minute, that would be 5 mg per minute. So just divided by 60. And because we want it in microgram per kilogram per minute, I'm just converting that further into microgram. So that's 5000 micrograms per minute. And then I'm going to divide that by 80 kg, which gives me 62.5 micrograms per kilogram per minute. That's not cool. So yeah, that's that. And then the next question, I think that's our final question. 70 seconds, 10 seconds and time, so be no point, not not 1 mL per hour. So yeah, that's our unit. But we're going to get 2 mL per hour and we have a dose of 60 micrograms per minute, so that's not point not 6 mg per minute. And if we can run that into our I'm dividing it by 60 again. So it's no point, not not 1 mg per hour. And then if we look at the concentration, that's not 0.1%. So that's not 0.1 g in 100 millimeters. And if you keep converting it and, um, simplifying it, it gets down to 1 mg in one millimeter. So one, so not point. Not not 1 mg is equal to 8.1 millimeter in the solution. So the infusion rate would be just not quite not, not 1 mL per hour. Um, I believe that was Yeah, that's the last question. Any other questions with these lots of questions? Nothing in the chart at the moment. Cool, Cool. So it's a really dry topic is just maths. Not really much medicine. So final tips would be so provided that you're going through the questions chronologically. You still have three sections left after the calculations, Um, so you'd have to 22 to market questions left. So if you are spending too much time on the calculations question, I would suggest you just move on, because arguably the ones at the back are quite easy to, um Okay, Right. And if your answer has more than three decimal places or some weird number was like recurring decimals. And the question doesn't say, you know, give your answer around 22 decimal places or something like that. Uh, it does suggest you probably got it wrong because they are quite, um, kind. And that way they do suggest, like, running to the nearest three significant figures or whatever like that. So, yeah, that's, uh, those would be my final tips. It's just calculations. You can do this. So thank you guys. And good luck. This is my email. If you have any questions and that's the feedback link. I do think they're going to, um, share it with you guys by email, so Yes, thank you very much. Thank you. So there's one other question is will be able to work out the answers on a piece of paper. Yeah. So you do get a piece of paper and you can write it down. Perfect. Thank you. So I've sent the feedback from in the chat. If everyone could please fill that out, it will only take a couple of seconds. Um, if we just give maybe a couple more minutes to see if there's any more questions in the chat. If not, we'll send it there. I think that's all good. Thank you very much. Thank you, guys. It's a pretty straightforward protection. All right, Good luck. Thank you. Thank you.