Pharmaceutics I Lecture 1 PDF

Pharmaceutics I Second year Semester 1 2024-2025 Pharmaceutical Calculation  Pharmaceutical Calculation By the end of the lecture, students will acquire the following LOs: 1. Discuss methods of certain pharmaceutical calculations. 2. Distinguish the proper pharmaceutical and medical ter...

Pharmaceutics I Second year Semester 1 2024-2025 Pharmaceutical Calculation  Pharmaceutical Calculation By the end of the lecture, students will acquire the following LOs: 1. Discuss methods of certain pharmaceutical calculations. 2. Distinguish the proper pharmaceutical and medical terms, abbreviations and symbols included in pharmacy field..  Compounded prescriptions may be desired for a number of reasons, 1. the need to adjust the strength or dose of a commercially available product to meet the specific requirements of a patient (e.g., a pediatric patient); 2. the need to provide product more organoleptically acceptable (e.g., taste) to a pediatric or veterinary patient; 3. the need to prepare a different dosage form (e.g., a liquid) than the commercially available product (e.g., a tablet) to meet requirements of a patient unable to swallow the existing dosage form (e.g., a pediatric or elderly patient); 4. the need to prepare a dosage form free of an agent (e.g., sugar, preservatives) in the commercially available product that cannot be tolerated by a patient; and 5. the need to provide a patient with a specifically designed formulation drug or drug combination not available as a commercial product.  Reducing and enlarging formulas 1-From the following formula, calculate the quantity of each ingredient required to make 240 ml. of calamine lotion. Calamine 80 g. Zine oxide 80 g. Glycerin 20 ml. Bentonite magma 250 ml. Lime water, to make1000 ml. Factor = 240/1000 =0.24 Using the factor 0.24 (since 240 ml. is 0.24 x 1000 ml.), the quantity of each ingredient is calculated as follows:  Calamine 80 x 0.24 = 19.2 g. Zine oxide 80 x 0.24 = 19.2 g. Glycerin 20 x 0.24 = 4.8 ml. Bentonite magma 250 x 0.24 = 60 ml. Lime water, to make 1000 x 0.24 = 240 ml. Is the total quantity is given? Use the formula listed below to calculate the amount of each ingredient that should be used to make 120 ml of Phenolated Calamine Lotion. R/ Calamine lotion……… 990 ml Liquid phenol………… 10 ml Answer: Total quantity = 990 + 10 = 1000 ml F= 120/1000 =0.12 Roman Numerals  Roman numerals are used to express a large range of numbers by use of letters of alphabets. Roman numerals can record quantities in prescriptions if ingredients are measured by the common or apothecary systems. Letters used in Roman Numerals SS=1/2 i or I=1 V or v=5 x or X=10 L or l=50 c or C=100 D or d=500 m or M=1000 Rules used 1- When Roman numeral is repeated, it doubles its value; When a Roman numeral is repeated three times, it triples its value. Ex: I= 1, II= 2, III=3 X= 10, xx =20, xxx =30 * N.B: Roman numeral may not be repeated more than three times in succession. Ex: 4 is written iv not iiii Rules used 2- when two different letters are present, two cases exist; If the second letter is smaller in value, the quantity is the sum of their values. -vi=6, -xii=12, -Li=51, -Lxvi=66, -Lxxxviii=88, -dc=600, -mdclxvi=1666 3- When the second has a value greater than the first; the smaller is to be subtracted. iv=4, ix=9, xl=40, xc=90 Rules used 4- I, X and C, are customarily used as "subtractors". Each is used to subtract only from the two characters on next higher value than itself thus X is used to subtract from L and C, but not from D or M. XLIX=49, not IL Rules used 5- A "subtractor" is placed so as to precede only one character higher than itself. xix=19, not ixx 6- Roman numerals are sometimes combined with the abbreviation for ½; ss. Roman numerals are written in lower case when used with ss, such as iss to indicate 1 1/2 (1.5). Rules used 7- When Roman numeral of a lesser value is placed between 2 greater values, it is first subtracted from the greater numeral placed after it, then that value is added to the other numeral. xxix = 10+10+(10-1)= 29 xiv =10+(5-1) = 14 MCM = 1000 + (1000-100) =1900 Examples Write the following in Roman Numerals 18: xviii 99: xcix 1984: Mcmlxxxiv Write the following in Arabic Numerals Mcmlxxii: 1972 Xcviii: 98 Mcmlxv: 1965 Convert the following Roman numerals to Arabic numbers CCXXXII: XII: LVI: Answer (232, 12, 56) XL: IVss: XCIV XIV: XLIII: CIII: Answer (40, 4.5, 94, 14, 43, 103) Examples in prescriptions: R/ Aspirin tablets 5 gr xxxii The Roman numeral XXXII below dosage form (aspirin tablets-5 gr) indicates the number of tablets to be dispensed. R/ Calamine lotion ƒ℥ IV Roman numeral IV following the symbol for a fluid ounce (ƒ℥ ) indicates that 4 fluid ounces of calamine lotion should be dispensed Metric system Metric System Meter is the primary unit of length Liter is the primary unit of volume Gram is the primary unit of weight milli- to denote (1/1000) of the unit, centi- to denote (1/100) of the unit, deci- to denote (1/10) of the unit. Deka = (10) x the unit, Hekto = (100) x the unit, Kilo = (1000) x the unit. Metric System Length : Km, m, dm, cm, mm, μm, nm. Volume: KL, L, dl, cl, ml, μl. Weight: Kg, g, dg, cg, mg, μg, ng. Examples Solve the following. (1) 4000 mg = __________g (2) 0.04 kg = __________mg (3) 3.47 L = __________ml (4) 142 mcg = __________g (5) 250mg = __________g (6) 3L = __________ml (7) 0.25 g = __________mg (8) 0.001 g = __________mg Answer: (4 g, 40000 mg, 3470 ml, 0.000142 g, 0.25 g, 3000 ml, 250 mg, 1 mg)  1500 tablets are made from 0.75 g of scopolamine HBr. How many milligrams of scopolamine HBr are contained in each tablet? Answer: Units must be similar 0.75 g = 0.75*1000 = 750 mg 750 mg >>> 1500 tablets X mg >>>1 tablet, x= 0.5 mg Fifty-five milligrams of strychnine SO4 are divided into 45 doses. How many grams of strychnine SO4 are contained in each dose? Answer: Units must be similar 55 mg = 55/1000 g = 0.055 g 0.055 g>>> 45 doses X g >>>1 dose, x= How many milliliters of tetracycline suspension, contains 250 mg of tetracycline in each 5 mL, must be administered to give a patient 150 mg? Answer: 5 mL>> 250 mg X ml >>> 150 mg X= 3 mL If 3 doses of a liquid preparation contain 7.5 grains of a substance, how many doses will be needed to give a patient 80 grains of the substance?? Answer: 3 doses>>> 7.5 gr X doses>>> 80 gr X= 32 doses How many grams of aspirin would be needed to make 500 aspirin tablets if each tablet contains 325 mg of aspirin? Answer: Units must be similar 325 mg = 325/1000 g = 0.325 g 1 tablet>>> 0.325 g 500 tablets >>>x g, x= 162.5 g How many milliliters of U-100 insulin should be used to obtain 40 units of insulin?U-100 insulin contains 100 units/mL? Answer: 1 mL >> 100 units X mL>>> 40 units X = 0.4 mL Add 7.25 L., and 875 ml. Reduce the results to milliliter. Answer:- 7.25 L= 7.25*1000= 7250 ml 7250+875 = 8125 ml A vitamin capsule contains 6.25 µg of vitamin B 12. How many capsules can be prepared from 1.0 g of vitamin B 12. Answer:- 1g = 106 µg 1 cap >> 6.25 µg X cap >> 106 µg X = 106 /6.25 = 160.000 capsules Apothecaries' system Apothecaries' system The basic unit of weight is grain (gr) The basic unit of volume is mimim (m) The amount is expressed in Roman numerals after the apothecaries symbol (gr ss). Arabic numerals can be used before the apothecaries symbol (12 ounce: ℥ xii) Apothecaries fluid measure Volume Gallon (gal. or C): 4 Quart (qt): 2 Pint (pt. or O): 16 ƒ℥: 8 ƒʒ:60 m Apothecaries weight measure weight lb (pound): 12 ℥: 8 ʒ:3 Э:20 gr Avoirdupois weight measure 1 oz (ounce) = 437.5 gr Examples How many f℥ iv bottles of Iodine Tincture USP, can be filled from one quart stock bottle? Answer: first convert quart to f ℥ 1 qt= 2*16 = 32 f ℥ 1 bottle = f ℥ iv (4 f ℥ ) X bottles = 32 f ℥ X = 8 bottles How many 5-gr capsules of aspirin can be made from 4 oz of aspirin Answer: 1 oz= 437.5 gr, 4 oz = 4*437.5= gr 1 capsule >> 5 gr X capsules >>> 4*437.5 gr, x =  Reduce ℥ ss ʒii Эi to grains Answer: ℥ ss = 1/2 x 480 (8*3*20) gr. = 240 gr. ʒ ii = 2 x 60 ( 3*20) gr. = 120 gr. Эi = 1 x 20 gr. = 20 gr. Answer = 380 gr. If a drug costs $8.75 per oz (avoir.), what is the cost of 2 ʒ? Answer: 1 oz = 437.5 gr, and 2 ʒ = 120 gr. 437.5 gr >>> 8.75 $ 120 gr >>>>>>x $ x= 2.4 $, answer.  Convert ℥ii ʒii to avoirdupois weight Answer:- ℥ii = 8*3*20*2 = 960 gr Ʒii= 3*20*2= 120 gr So, ℥ii ʒii = 1080 gr 1 oz……………437.5 gr x oz……………1080 X= 2 oz , 205 gr  How many grains of a chemical is left in a 1 oz bottle after Ʒvii are dispensed from it? Answer:- Before: 1oz= 437.5 gr℥ Taken: 3*20*7 = 420 gr So, left = 437.5- 420= 17.5 gr  If Silver Nitrate, USP, costs $2.09 per ounce, what is the cost of 4.8 g? Answer:- 1oz= 437.5 gr 1 gr = 0.065 g X gr= 4.8 g, x = 73.85 gr 437.5 gr >>> $ 2.09 73.85 gr >>> ?? Conversion Conversion 1 in = 2.54 cm 1 min.= 0.06 ml 1 fʒ= 4 ml 1 f ℥= 30 ml 1 kg= 2.2 lb 1 gr = 0.065 g Examples  The fiber length of a sample of purified cotton is 6.35 mm. Express the length in inches. Answer:- 6.35 mm= 0.635 cm 1 in. 2.54 cm X in. 0.635 cm X = 0.635/2.54 = 0.25 in.  Convert fʒ iiss to milliliters. fʒ iiss = 4*2.5= 10 ml Convert Oiiss to milliliters. O= 16 f℥ Oiiss= 2.5*16 f℥= 2.5*16*30 ml= 1200 ml Convert 15 kg to pounds. Answer: 1 kg >> 2.2 lb 15 kg >> x X= 15*2.2 = 33 lb  Convert the following - f℥ iv = ml - 1/4 gr = mg - 5 gr = g - 15 ml = f℥ - 500 mg= gr Calculation of doses Calculation of doses Dose: A specified quantity of a therapeutic agent, such as a drug or medicine, prescribed to be taken at one time or at stated intervals for certain days, weeks, months or years. In the signature On the label Fʒi or 5ml One teaspoonful Fʒii or 10 ml Two teaspoonful or one dessertspoonful F℥ss or 15 ml One tablespoonful F℥ or 30 ml One coffeecupful or Two tablespoonful Apothecary fluid measure 6 teaspoonfuls = 1 fluidounce. Examples  Tetracycline susp. Sig. fʒii q.i.d.x 2days, then fʒi q.i.d. The doctor who phoned in the prescription said (give the patient enough to last five days) *fʒ required for 1st 2 days= 2*4*2= 16 fʒ *fʒ required for last 3 days= 1*4*3= 12 fʒ * Total fʒ required = 16+12= 28 fʒ. So, to dispense 28*5= 140 ml How many teaspoonfuls would be prescribed in each dose of an elixir if f℥vi contained 18 doses? 6 teaspoonfuls = 1 fluidounce. f℥vi =6*6 =36 teaspoonful 36 teaspoonful.............. 18 dose x teaspoonful ……………. 1 dose X =36/ 18 = 2 teaspoonful If a doctor prescribed “f℥ tid” of Maaloxâ, what amount would you tell the patient to take using household equivalents 2 Tbsp (6 tsp*) three times daily. If 0.050 g of a substance is used in preparing 125 tablets, how many micrograms are represented in each tablet? 0.05 g= 50000 mcg 50000 mcg>>> 125 tablets X mcg >>>> 1 tablet X= If a preparation contains 5 g of a drug in 500 mL, how many grams are contained in each tablespoonful dose? 1 tablespoonful = 15 mL 5 g >>> 500 mL X g >>> 15 mL, x = 0.15 g How many grams of a drug substance are required to make 120 mL of a solution each teaspoonful of which contains 3 mg of the drug substance? 1 tsp = 5 mL 5 mL >>> 3 mg 120 mL>>> x mg X = 0.072 g, How many drops would be prescribed in each dose of a liquid medicine if 15 ml. contained 60 doses? The dispensing dropper calibrates 32 drops per ml. 15 ml.............. 60 doses x ml………... 1 dose 1dose= 15/60 = 0.25 ml 1ml.............. 32 drops 0.25 …….. y drops Y= 0.25 *32 = 8 drops Another answer 32 drops …………..1 ml Y drops ……………15 ml Y = 15*32 = 480 drops 60 dose.............. 480 drops 1 dose ……………. Y drops y = 480/60 =8 drops  Total amount of a medicine Total amount = number of doses x size of dose How many milliliters of a liquid medicine would provide a patient with 2 tablespoonfuls twice a day ( ƒ℥ I b.i.d) for 8 days? No of doses = 2*8= 16 dose Size of dose = 2*15=30 ml Total amount = number of doses x size of dose = 16*30= 480 ml  Cyclophoshamide 50 mg tablets are used in treatment of neoplasms (abnormal growths or tumors) and have a dose of 5 mg/kg of body weight in a single dose daily. How many tablets should be dispensed to a 110-lb patient as a ten-day regimen? (NOTE: A regimen is a treatment plan.). Fist, make weight units uniform 1 kg >>> 2.2 lb X kg >>> 110 lb, x = 50 kg Calculate the dose 5 mg>>> kg X mg>>> 50 kg, x = 250 mg.( size of each dose in mg) Size of each dose in no of tablets 1 tablet >>>50 mg X tablets>>> 250, x = 5 tablets No of tablets = 5 tablets (once daily)* 10 (10 day regimen)= 50 tablets  If a liquid drug to be taken 3 times daily, and if 180 mL to be taken in 4 days, how many tablespoonful prescribed/ dose?? No. of doses= 3*4= 12 dose. 180 mL>> 12 dose X mL>> 1 dose, x = 15 mL * What volume in ml a soln of 2.5 g KSCn/ 100 ml, will provide 100 mg KSCn 3 times daily for 10 days?? Amount of medicine= 100*3*10 = 3000 mg =3 g (no dose* size ) 2.5 >>> 100 ml 3g>>> x ml, x= 120 ml IV infusion of 1 g carbenicllin in 20 ml, how many ml to be given to patient 154 lb if the dose was 200 mg/kg/day? Patient wt: 1 kg>> 2.2 lb, x kg >> 154 lb, x = 70 kg Patient dose= 200*70 = 14000 mg = 14 g. 1g>> 20 ml 14 g>>> x ml Children  Calculation of doses for children based on age, weight and BSA 𝑨𝒈𝒆 (Young's rule )Dose = x Adult dose = child dose 𝑨𝒈𝒆+𝟏𝟐 𝑨𝒈𝒆 (𝒊𝒏 𝒎𝒐𝒏𝒕𝒉𝒔) Fried`s rule for dose infants = *adult dose 𝟏𝟓𝟎 𝑾𝒆𝒊𝒈𝒉𝒕 𝒊𝒏 𝒍𝒃 (Clark`s rule dose for child ) Dose= 𝟏𝟓𝟎 (𝒂𝒗𝒆𝒓𝒂𝒈𝒆 𝒘𝒆𝒊𝒈𝒉𝒕 𝒊𝒏 𝒂𝒅𝒖𝒍𝒕) x adult dose 𝑩𝑺𝑨 𝒐𝒇 𝒄𝒉𝒊𝒍𝒅 (𝒊𝒏 𝑴𝟐) approximate dose for child= * adult dose 𝟏.𝟕𝟑 (𝒂𝒗𝒆𝒓𝒂𝒈𝒆 𝒅𝒖𝒍𝒕 𝑩𝑺𝑨) Examples The adult dose of a drug is 500mg.What is the dose for a 2 year old child? Young's rule = 2/2+12 *500= If the usual adult dose of a drug is 325 mg., what is the dose, in milligrams, for a child having 66 lb body weight? Clark`s rule dose for child Dose= child weight/150 * adult dose = 66/150 * 325 = mg  References 1. Rees JA, Smith I, Watson J. Introduction to pharmaceutical calculations. Pharmaceutical Press; 2015 Apr 21. 2. Ansel HC. Pharmaceutical calculations. Lippincott Williams & Wilkins; 2012 Oct 26.. 3. Zatz JL, Teixeira MG. Pharmaceutical calculations. John Wiley & Sons; 2013 Mar 27. 4. Agarwal P. Pharmaceutical calculations. Jones & Bartlett Publishers; 2014 Sep Thank you