Orwa Posted January 26, 2008 Share Posted January 26, 2008 In CPR page24 the Question24: For children, streptomycine is to be administred at a dose of 30 mg/kg of body weight daily in divided doses every 6-12 hr. The dry powder is dissolved by adding water for injection, USP is an amount to yield the desired conc as indicated in the formula: Approximate conc mg/ml volume 200 4.2 250 3.2 400 1.8 Reconsituuting at the lowest conc, what volume(in ml) would be withdrawn to obtain one day's dose for 50-lb child? A: 3.4ml B: 22.7ml C:2.250ml D:2.27ml The answer is A, but i did not get it? Please someone explain to me what dose it mean( reconstituting at the lowest possible concentration). How they get this answer? Any help will be greatly appreciated. Thanks. Quote Link to comment Share on other sites More sharing options...
Isabel Posted January 27, 2008 Share Posted January 27, 2008 Hi, Orwa. The lowest possible concentration is the one that allows you to withdraw the necessary amount of drug you need. In this case, you'd need per day: 30mg x 22.7Kg = 681mg of streptomycin. Now, the lowest concentration they show you is 200mg/ml by adding 4.2ml. Therefore, you have 200mg/ml x 4.2ml= 840mg of the drug, which is more than enough for what you need (681mg). Using this concentration now you can get the volume you'd need: 200mg-----1ml 681mg------X 681mg X 1ml / 200mg = 3.4ml If hope this explanation cleared your doubt. By the way, I solved all the problems of this chapter just yesterday, but the previous question to this one was hard to me. It's No. 11, the answer is B. 8.00ml/hr. and I got 7.28 instead. Did you get it right?? Another thing... Do you know if we need to know well the Apothecary and Avoirdupois system?? Isabel Quote Link to comment Share on other sites More sharing options...
Orwa Posted January 28, 2008 Author Share Posted January 28, 2008 Dear Isabel, thanks a lot for your instant response, I really appreciate your cooperation. My friend told me that it is not imoprtant to memorize Apothecary and Avoirdupois system, but I am nor really sure and I will not spend any time on them. If you have any question, I am ready for help. Best wishes. Quote Link to comment Share on other sites More sharing options...
pinky786 Posted January 31, 2008 Share Posted January 31, 2008 Dear Isabel, thanks a lot for your instant response, I really appreciate your cooperation. My friend told me that it is not imoprtant to memorize Apothecary and Avoirdupois system, but I am nor really sure and I will not spend any time on them. If you have any question, I am ready for help. Best wishes. Dear Isabel, thanks a lot for the reply cause I was also checking the answer for that question too, you also ask for the question # 11, according to my understanding maybe that can help you if not do correct me as well the maintainance dose for childeren is 1mg/kg/hr and the child weigh 40 lbs, if we convert weight from lbs to kg that would be 18.18 kg and the dose needed would be 18 mg/hr, now the conc. is 25mg/ml and the 10 ml would be 250mg/10ml and we add it to 100 ml dextrose so the total volume is now 110 ml and we have to calculate that how much drug is in 110ml , so divide 250mg/110ml and it will be 2.27mg/ml, now remember the dose for the child is 18.18 mg/kg/hr, so divide 18.18mg/2.27mg and you will get the 8ml/hr answer, that means 8ml contain 18.18mg, I hope that will help you, if not make my correction as well. Best wishes. Quote Link to comment Share on other sites More sharing options...
Isabel Posted January 31, 2008 Share Posted January 31, 2008 Thanks a lot pinky786!! I had forgotten to consider those extra 10ml you add to the 100ml of Dextrose!... Isabel Quote Link to comment Share on other sites More sharing options...
pinky786 Posted January 31, 2008 Share Posted January 31, 2008 You are more then welcome Isabel!! I have just started these calculations maybe i need help to calculate some, that would be so nice of you if you help me. Pinky Quote Link to comment Share on other sites More sharing options...
Isabel Posted February 1, 2008 Share Posted February 1, 2008 Hi, Pinky... Sure no problem... I'm also almost done with pharmacokinetics, and solved CPR's problems for this chapter. Isabel Quote Link to comment Share on other sites More sharing options...
pinky786 Posted February 3, 2008 Share Posted February 3, 2008 Hi Isabel! Please could you explain Question no.19,26,27,29 of CPR Chapter no.2, Pharmaceutical Calculations, that would be great. Thanks in advance. Pinky Quote Link to comment Share on other sites More sharing options...
Orwa Posted February 4, 2008 Author Share Posted February 4, 2008 Hi Pinky, here are the answers: Number19: Amount of ZnU in Ib is: 454*20/100= 90.8 If conc of ZnU is 3% then: 3/100= 90.8/Amount of powder after adding talc Amount of powder after adding tac= 90.8*100/3= 3026.7 Amount of talc added= 3026.7-454= 2572.7 g Number 26: amount of active ingredient in one tab=473(1pt)*1/40= 11.8 Amount of Active ingredient in 1/2 gal= 1892.5*1/10=189.25 number of tablets=189.25/11.8= 16 Number27: mOsmol/L= (wt of substance/mol weight )8 number of species* 1000 Page19 weight of substance= 147* 10/100= 14.7 mOsmol/L= (14.7/147)*3*1000= 300 or as solved in the page 28 Number29: atomic wt of K=39 not 30 as in the book eq wt= 74.5 mEq wt= 0.0745 Amount of KCL in 15 ml= 565* 15/3785(1 gal)= 2.23 so 2.23*1/0.0745= 30 mEq If you need any extra explanation, let me know Quote Link to comment Share on other sites More sharing options...
Isabel Posted February 4, 2008 Share Posted February 4, 2008 Hi, Pinky, Sorry I didn't answer before. I took the weekend off.. I needed to relax. Thanks, Orwa.. Quote Link to comment Share on other sites More sharing options...
pinky786 Posted February 4, 2008 Share Posted February 4, 2008 Hi Pinky, here are the answers: Number19: Amount of ZnU in Ib is: 454*20/100= 90.8 If conc of ZnU is 3% then: 3/100= 90.8/Amount of powder after adding talc Amount of powder after adding tac= 90.8*100/3= 3026.7 Amount of talc added= 3026.7-454= 2572.7 g Number 26: amount of active ingredient in one tab=473(1pt)*1/40= 11.8 Amount of Active ingredient in 1/2 gal= 1892.5*1/10=189.25 number of tablets=189.25/11.8= 16 Number27: mOsmol/L= (wt of substance/mol weight )8 number of species* 1000 Page19 weight of substance= 147* 10/100= 14.7 mOsmol/L= (14.7/147)*3*1000= 300 or as solved in the page 28 Number29: atomic wt of K=39 not 30 as in the book eq wt= 74.5 mEq wt= 0.0745 Amount of KCL in 15 ml= 565* 15/3785(1 gal)= 2.23 so 2.23*1/0.0745= 30 mEq If you need any extra explanation, let me know Hi Orwa! Thanks a lot for your detailed reply, thats great , I'll sure ask you if i have any further problems, you and Isabel are great help, best of luck to both of you. Thanks again. pinky Quote Link to comment Share on other sites More sharing options...
pinky786 Posted February 4, 2008 Share Posted February 4, 2008 Hi, Pinky, Sorry I didn't answer before. I took the weekend off.. I needed to relax. Thanks, Orwa.. Hi Isabel! Thanks anyways for your concern, you are great. Thanks. pinky Quote Link to comment Share on other sites More sharing options...
pinky786 Posted February 5, 2008 Share Posted February 5, 2008 Hi Pinky, here are the answers: Number19: Amount of ZnU in Ib is: 454*20/100= 90.8 If conc of ZnU is 3% then: 3/100= 90.8/Amount of powder after adding talc Amount of powder after adding tac= 90.8*100/3= 3026.7 Amount of talc added= 3026.7-454= 2572.7 g Number 26: amount of active ingredient in one tab=473(1pt)*1/40= 11.8 Amount of Active ingredient in 1/2 gal= 1892.5*1/10=189.25 number of tablets=189.25/11.8= 16 Number27: mOsmol/L= (wt of substance/mol weight )8 number of species* 1000 Page19 weight of substance= 147* 10/100= 14.7 mOsmol/L= (14.7/147)*3*1000= 300 or as solved in the page 28 Number29: atomic wt of K=39 not 30 as in the book eq wt= 74.5 mEq wt= 0.0745 Amount of KCL in 15 ml= 565* 15/3785(1 gal)= 2.23 so 2.23*1/0.0745= 30 mEq If you need any extra explanation, let me know Hi Orwa! Thanks a lot for your detailed reply, do you have the 5th or 6th edition of CPR, I have the 5th edition, I don't know if there is lot of new material included in the 6th edition, if you knew please let me know so that i can arrange for the 6th edition, once again thanks for your help. Good Luck. pinky Quote Link to comment Share on other sites More sharing options...
Orwa Posted February 5, 2008 Author Share Posted February 5, 2008 I don't know for sure if there is a big differnece, but I think I read in the forum that difference is not important. I have only the 6th edition and they wrote on the cover: New chapters in drug errors and bowel disorder. Revised chapter in drug interactio Best Wishes, Orwa. Quote Link to comment Share on other sites More sharing options...
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