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Questions and Answers
What is the maximum capacity of most class A and class B prescription balances?
What is the maximum capacity of most class A and class B prescription balances?
How is the percentage of error calculated?
How is the percentage of error calculated?
In the given measuring error example, what was the actual volume measured by the pharmacist?
In the given measuring error example, what was the actual volume measured by the pharmacist?
What is the weight found when checked on a high-accuracy balance if initially weighed 475 mg?
What is the weight found when checked on a high-accuracy balance if initially weighed 475 mg?
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What unit of measurement is considered the basic unit for weight in the apothecary system?
What unit of measurement is considered the basic unit for weight in the apothecary system?
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What is the equivalent weight of one dram (dr) in grains (gr)?
What is the equivalent weight of one dram (dr) in grains (gr)?
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According to the content, which of the following statements is true regarding the apothecary system?
According to the content, which of the following statements is true regarding the apothecary system?
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What is the formula represented for percentage of error in terms of approximate and exact measurements?
What is the formula represented for percentage of error in terms of approximate and exact measurements?
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How many mL are needed for a 250 mg dose of an antibiotic if it contains 125 mg per 5 mL?
How many mL are needed for a 250 mg dose of an antibiotic if it contains 125 mg per 5 mL?
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What is the decimal equivalent of 25%?
What is the decimal equivalent of 25%?
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If a cough medication contains 50 mg/mL, how many mL are required for a 100 mg dose?
If a cough medication contains 50 mg/mL, how many mL are required for a 100 mg dose?
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In the proportion 3:4 = x:12, what is the value of x?
In the proportion 3:4 = x:12, what is the value of x?
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To convert the ratio 1:3 to a percent, what is the resulting percent value?
To convert the ratio 1:3 to a percent, what is the resulting percent value?
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If an antilipidemic agent contains 5 mg per tablet, how many tablets are needed for a 35 mg dose?
If an antilipidemic agent contains 5 mg per tablet, how many tablets are needed for a 35 mg dose?
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What is 3% of 42?
What is 3% of 42?
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In the proportion a:b = c:12, if a = 6 and b = 8, what is the value of c?
In the proportion a:b = c:12, if a = 6 and b = 8, what is the value of c?
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What defines an improper fraction?
What defines an improper fraction?
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Which situation best illustrates a measurement's accuracy?
Which situation best illustrates a measurement's accuracy?
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How is a ratio typically presented?
How is a ratio typically presented?
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In assessing precision, which statement is most accurate?
In assessing precision, which statement is most accurate?
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What is a practical use of ratios in pharmacy practice?
What is a practical use of ratios in pharmacy practice?
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Which of the following represents a correct understanding of zeros in significant figures?
Which of the following represents a correct understanding of zeros in significant figures?
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When dispensing 10 mg metoclopramide per dose using 5 mg/mL solution, what is the correct volume to dispense for one dose?
When dispensing 10 mg metoclopramide per dose using 5 mg/mL solution, what is the correct volume to dispense for one dose?
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Which statement accurately defines lotions in terms of their composition?
Which statement accurately defines lotions in terms of their composition?
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What is the maximum mass that a triple beam balance can measure?
What is the maximum mass that a triple beam balance can measure?
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What distinguishes pastes from other semisolid dosage forms?
What distinguishes pastes from other semisolid dosage forms?
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Which characteristic is true for gels as semisolid dosage forms?
Which characteristic is true for gels as semisolid dosage forms?
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In the household system, how many milliliters does one dessertspoonful (dssp) approximately equal?
In the household system, how many milliliters does one dessertspoonful (dssp) approximately equal?
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What is the smallest mass that a triple beam balance can measure?
What is the smallest mass that a triple beam balance can measure?
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Which of the following statements about the apothecary and avoirdupois systems is NOT true?
Which of the following statements about the apothecary and avoirdupois systems is NOT true?
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What is the purpose of a spatula in a laboratory?
What is the purpose of a spatula in a laboratory?
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What is a primary difference between ointments and creams?
What is a primary difference between ointments and creams?
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What distinguishes a graduated cylinder from a beaker?
What distinguishes a graduated cylinder from a beaker?
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Which of the following describes the intended use of suppositories?
Which of the following describes the intended use of suppositories?
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How many grams are equivalent to one avoirdupois ounce?
How many grams are equivalent to one avoirdupois ounce?
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If a patient consumes one teaspoonful (5 ml) of Suprax suspension containing 100 mg/5 ml, how many total milligrams does the patient consume in ten days if taken twice daily?
If a patient consumes one teaspoonful (5 ml) of Suprax suspension containing 100 mg/5 ml, how many total milligrams does the patient consume in ten days if taken twice daily?
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Which piece of equipment is specifically used for transferring measurable amounts of liquid?
Which piece of equipment is specifically used for transferring measurable amounts of liquid?
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What is the typical viscosity of lotions compared to other semisolid forms?
What is the typical viscosity of lotions compared to other semisolid forms?
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What is the density of a substance if its mass is 300 grams and its volume is 100 cubic centimeters?
What is the density of a substance if its mass is 300 grams and its volume is 100 cubic centimeters?
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What is the primary function of a watch glass in the laboratory?
What is the primary function of a watch glass in the laboratory?
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What type of emulsion are most lotions formulated as?
What type of emulsion are most lotions formulated as?
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What defines a suppository in comparison to other dosage forms?
What defines a suppository in comparison to other dosage forms?
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What characteristic does a conical flask have that allows for mixing by swirling?
What characteristic does a conical flask have that allows for mixing by swirling?
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In the avoirdupois system, how many kilograms are equivalent to 110 lbs?
In the avoirdupois system, how many kilograms are equivalent to 110 lbs?
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What is the volume range for a typical beaker used in laboratory settings?
What is the volume range for a typical beaker used in laboratory settings?
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Which of the following correctly represents the measurement conversion of one quart (qt) in liters?
Which of the following correctly represents the measurement conversion of one quart (qt) in liters?
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What is the relationship between density and specific gravity for water at 4°C?
What is the relationship between density and specific gravity for water at 4°C?
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Study Notes
Pharmaceutical Calculation Techniques and Terminologies
- The presentation covers pharmaceutical calculations and terminology, presented by Yibekal M, specializing in epidemiology.
- The date of the presentation is 12/8/2024.
Emulsion
- An emulsion is a dispersion where a liquid phase is distributed throughout another immiscible liquid phase (vehicle).
- Emulsions consist of at least two immiscible liquid phases.
- The dispersed phase is the internal phase, and the dispersion medium is the external or continuous phase.
- Advantages of emulsions include increased drug bioavailability (by administrating hydrophobic drugs in a dissolved state) and increased drug stability & prolonged drug action.
- Oil-in-water (o/w) emulsions have the aqueous phase comprising over 45% of the total weight, and use a hydrophilic emulsifier.
- Water-in-oil (w/o) emulsions have the oil phase as the continuous phase, predominantly for external use.
- Multiple emulsions contain droplets of another emulsion (e.g., w/o/w, o/w/o), relevant for delayed/sustained drug delivery systems.
- Microemulsions are visually homogeneous, isotropic systems with low viscosity.
Semisolid Dosage Forms
- Semisolid dosage forms, such as ointments, creams, gels, pastes, and lotions, can change shape upon force application.
- They are used for topical or systemic drug action.
- Topical applications can target local effects or systemic absorption.
Ointments
- Ointments are semisolid preparations for external application to skin or mucous membranes (medicated or non-medicated).
- They can act as emollients, protective barriers, or vehicles for medication incorporation.
- Ointment bases are categorized into oleaginous (hydrocarbon), absorption, water-removable, and water-soluble types.
Oleaginous Bases
- Oleaginous (hydrocarbon) bases have an emollient effect, protect against moisture loss, are greasy, and hard to wash off.
- Examples include petrolatum and waxes.
Absorption Bases
- Absorption bases are of two types, either permitting aqueous solutions or resulting in W/O emulsions, like hydrophilic petrolatum.
Water-Removable Bases
- Water-removable bases (creams) are easily washed from the skin.
- They are used as emollients and are oil-in-water emulsions.
- Examples include hydrophilic ointment and vanishing cream.
Water-Soluble Bases
- Water-soluble bases don't have oleaginous components and absorb water to the point of solubility.
- Examples include polyethylene glycol (PEG) ointment.
Creams
- Creams are semisolid dosage forms with one or more drug substances dissolved or dispersed in o/w or w/o emulsion bases.
- Creams are typically non-washable or washable.
- Creams are easier to spread and remove compared to ointments.
Gels
- Gels are semisolid systems with dispersions of small or large molecules in an aqueous liquid vehicle rendered jelly-like by a gelling agent.
Lotions
- Lotions are low- to medium-viscosity preparations for topical application to unbroken skin.
- They are liquid suspensions or emulsions of dispersed solid or liquid materials in an aqueous vehicle.
- Most lotions are oil-in-water (o/w) emulsions; water-in-oil emulsions (w/o) can be used too.
Pastes
- Pastes are semisolid dosage forms with a large proportion of solid components.
- Pastes are thicker and stiffer than other semisolid dosage forms.
- Pastes typically include solid particles (over 25%) dispersed in oleaginous ointments (like petrolatum).
Suppositories
- Suppositories are solid or semisolid masses for insertion into body orifices (rectum, urethra).
- They soften, melt, or dissolve, exerting local or systemic effects.
- Types include rectal suppositories (cylindrical and tapered).
- Vaginal suppositories are oval, typically weighing around 5 g.
- Urethral suppositories (bougies) are also used.
- Suppository bases should be physically and chemically stable; non-irritating, nontoxic, non-sensitizing, and physiologically inert. They should remain solid at room temperature but soften, melt, or dissolve readily at body temperature(melting temperature ranges for different types of bases are mentioned). -Cocoa butter as an example is shown to melt just below body temperature.
- Water-soluble and water-miscible bases have slower softening compared to cocoa butter.
- Bases such as glycerinated gelatin and polyethylene glycols are listed as examples of water-soluble and water-miscible bases.
- Foam is a liquid-based dispersion of gas dispersed as thin films.
Aerosols
- Aerosols are colloidal dispersions of liquids or solids in gases.
- Some aerosol emissions are for inhalation and others are for topical skin or mucous membrane application.
Measuring Pharmaceutical Quantities
Mathematical Review
- A fraction indicates a portion of a whole number, consisting of a numerator (top) and denominator (bottom).
- A proper fraction has a numerator smaller than its denominator, while an improper fraction has a numerator greater than or equal to its denominator.
- Accuracy represents the closeness of a measurement to the desired or actual quantity, while precision represents its reproducibility.
Accuracy & Precision
- Accuracy is the measure of how close a measurement is to the true value.
- Precision is the measure of how close repeated measurements are to each other.
- Pharmaceutical measurements require both accuracy and precision
- Examples include measurement discrepancies related to quantities to be weighed (e.g., 125 mg).
Significant Figures
- Rule #1: Digits other than zero are significant
- Rule #2: A zero between digits is significant
- Rule #3: Final zeros after a decimal point are significant
- Rule #4: Zeros used only to show the location of the decimal point are not significant
Ratio & Ratio Strength
- Ratio is the relative amount of two quantities (e.g., one to the other).
- A colon separates the numbers in a ratio.
- Ratios are used in pharmacy to express drug concentration, or weight/dose of a drug given in a delivery unit or volume.
Exercise Problems
- A variety of practice problems (using different drugs and dosages) are provided (cimetidine, metoclopramide & dicloxacillin).
Proportion
- Proportion represents the equality between two ratios.
- Proportions can be expressed in three standard forms (a:b = c:d or a/b = c/d).
- The extreme values are represented by "a" and "d".
- The mean values are represented by "b" and "c".
- Example exercise problems to demonstrate ratios and proportions involving specific drugs are provided.
Percent
- Percent is a type of ratio representing per hundred.
- To change a percent to a fraction, remove the percentage sign and place the number over 100, then reduce to the lowest terms.
- To change a percent to a decimal, remove the percentage sign and divide by 100.
- To convert a decimal into percentage, multiply the decimal value by 100 and add the percentage symbol.
- Examples demonstrating changing ratios, decimals, and percentages into one another are shown.
- Three different ways to demonstrate calculation of fractions.
System of Measurement Used in Pharmacy
- Pharmacy measurements require accurate weight and volume measurement.
- Measurement systems include Metric, Apothecary, Household, and Avoirdupois systems.
- Basic units for each of these measurement systems are given.
Metric System (International System of Units)
- Introduced in France in the late 1790s, it uses multiples of 10 to define various ranges of quantities.
- Its fundamental units include meters (length), kilograms (mass), and liters (volume).
- Prefixes are added to the base units (e.g., milli-, centi-, kilo-) to indicate subdivisions or multiples of 10. Units such as atto, femto, pico, nano, micro, milli, centi and deci and deca, hecto, kilo, myria, mega, giga, tera , peta and exa are included with their numerical value counterparts.
Guidelines for the Correct Use of the SI
- General guidelines for expressing units in scientific notation
- Periods are usually not added after unit symbols except at the end of a sentence or in headings
Units - Measurement, Weight, and Volume
- Measures of length are given.
- Measures of volume are given.
Exercise Problems
- A collection of practice problems showcasing the conversion between various measurement systems is provided (e.g., liters and milliliters, grams and kilograms).
Measure of Weight
- The basic unit of weight in the metric system is the gram (g).
- A gram is approximately equivalent to the weight of 1 cubic centimeter (cc) or 1 milliliter (mL) of water at 4°C
- Weight conversion tables are presented for basic units: kilogram (kg), dekagram (dag), hectogram (hg), decigram (dg), centigram (cg), milligram (mg), microgram (mcg).
Example Problems
- Various examples demonstrating practical calculations using different weight measurement conversions are included
Sensitivity and Capacity of Balances in Pharmacy
- Two main types of balances in prescription settings are Class A and B.
- Sensitivity is the smallest discernible weight change, and sensitivity requirements (SR) vary between classes.
- Capacity is the maximum measurable weight.
Percentage of Error
- Defined as the maximum potential error multiplied by 100 and divided by the desired amount.
- It has implications in weighing or measuring liquid quantities (e.g., volume measurement errors)
Example Calculation Problems
- Different example problems demonstrate calculations of percentage of error for different contexts (such as volume and weight measurements).
Apothecary System of Measurement
- Traditional system used for medication measurement in the past.
- Basic units include grain (gr), dram (dr), and ounce (oz).
- Conversion tables for apothecary and metric systems are presented.
Household System of Measurement
- Commonly used at home, without precise measuring equipment.
- Household units include teaspoonfuls (tsp), dessertspoonfuls (dtsp), tablespoonfuls (tbsp), ounces (oz), wine glasses, coffee cups, glasses, and quarts (qt).
- Corresponding values in the milliliters (ml) are listed
Avoirdupois System of Measurement
- The grain measurements are identical in the Avoirdupois and Apothecary systems.
- The units ounce (oz) and pound (lb) differ in the number of grains between these two systems.
- Conversion tables for Avoirdupois measurements are provided (e.g., kg to lb, oz to gr, gr to mcg).
Density, Specific Gravity, and Specific Volume
- Density is mass per unit volume (e.g., g/cc, g/mL)
- Specific gravity is the ratio of the weight of a substance to the weight of an equal volume of a standard (usually water).
- Specific volume is the reciprocal of specific gravity.
- Water is the standard for liquids and solids; Hydrogen is the standard for gases.
- Units and typical values for density, specific gravity, specific volume are discussed as well as corresponding example problems.
Percentage Preparations
- Percentage preparations express the amount of active and inactive ingredients in a preparation in terms of percentage concentrations.
- Types include weight-in-volume, volume-in-volume, and weight-in-weight percentages
Special Considerations in Percentage Calculations for Percentage Preparations
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The nature of the ingredients determines the calculation basis.
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Powdered substances dissolved or suspended in liquids are calculated on a weight-in-volume basis.
-
Mixing powdered substances and/or liquid ingredients with a solid or semisolids is calculated on a weight-in-weight basis
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Liquid components in liquid preparations are calculated on a volume-in-volume basis
Percentage Preparations in Practice
- Percentage concentrations in labeling are restricted to cases where the active therapeutic agent (ATI) dosage is not specific.
Examples and Calculations of Percentage Preparations
- The presentation includes multiple exercise problems covering different types of percentage preparations and common units in pharmacy.
Ratio Strength Solutions
- Concentration expressions for weak solutions (or solids) are a different way of expressing percentage strengths.
- Percentage strength is a part per hundred ratio strength, whereby percentage & ratio strength conversion can be achieved via proportion.
Parts per Million (PPM) and Parts per Billion (PPB)
- PPM and PPB values are dimensionless & used to express the concentration of very dilute solutions by representing the ratio of 1 part substance per 1 million or 1 billion parts of the total mixture, respectively (e.g., fluoride level additions to drinking water).
Concentrations Based on Moles and Equivalents
- Molecular weights and moles of a compound are used in the comparison of two or more compounds.
- Molecular weight is the weight(in grams) of 1 mole (mol) of a compound.
- Equivalent weight is a compound's molecular weight divided by the number of valence or ionic charges in solution, accounting for the chemical activity of an electrolyte.
- One equivalent (Eq) is the number of grams in 1 mole of a compound divided by its valence.
- A milliequivalent (mEq) represents 1/1000 of its gram equivalent weight, in milligrams.
- Example illustrating how to calculate the concentration of a solution, in percent w/v, that contains 2 mEq of Potassium Chloride per milliliter is included.
- Values for common ions are provided in tables
Molarity, Normality, and Molality
- Molarity (M) is the moles of solute per liter of solution.
- Normality (N) is the gram equivalent weight of solute per liter of solution.
- Molality (m) is the moles of solute per kilogram of solvent.
International Units (IU)
- Units are amounts of medication with different sizes for each drug, standardized internationally.
- Examples use Vitamins, Insulin, Heparin and Penicillin.
- Concentrations are commonly (e.g., 100 units/mL or 500 insulin units per milliliter of solution or suspension)
Dilution and Concentration
- Dilution involves decreasing the concentration by adding a diluent.
- Concentration increases by adding more active ingredient or by evaporating the diluent.
- Problems involving dilution and concentration can be solved via the relationship of quantity1 × concentration1 = quantity2 × concentration2 (e.g., stock solution dilution).
- Percentage strengths of substances can be calculated via the equation above (e.g., dilute a 50% w/v stock solution to make 200 mL of a 5%w/v solution).
- Problems related to using different weights of multiple solutions to create a new solution (e.g., combining multiple preparations of Zn oxide ointment to create a 10% ointment) can be solved.
Enlarging and Reducing Formulas
- The need to prepare different amounts of a pharmaceutical product depends on the setting (community pharmacy, hospital, outsourcing, or manufacturing).
- Methods for expanding or reducing formulas (e.g. ratio or proportions, factor method) can be easily illustrated via example problems.
Calculating Doses
- Dosage calculations are often related to particular patient weight and age.
- Formulas based on adult dose and patient weight & age, can be used (Clark's rule, Young's rule, and Fried's rule).
- Body surface area (BSA) and adult dosage can also help determine the needed dosage for a child.
Pharmaceutical Equipment
- Various pieces of pharmaceutical equipment (e.g., mortars/pestles, water baths, beam/digital balances, spatulas, watch glasses, measuring cylinders, conical flasks, beakers, pipettes, droppers, electronic mortar & pestle, greasy proof paper & amber dispensing bottles, ointment slabs & ointment jars) and their uses are described.
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Description
This quiz covers essential measurements and calculations used in pharmacy classes. Participants will test their knowledge on prescription balances, error calculations, and dosage conversions based on the apothecary system. Perfect for students in pharmacology or pharmacy technician programs.
