Pharmaceutical Calculations: Units, Prescriptions, Measurements, Density, and Specific Gravity

Vocabulary flashcards reviewing pharmaceutical calculations, system of units, prescription components, latin abbreviations, volumetric and weighing instruments, aliquot method, percentage error, density, and specific gravity.

Reducing (Formulas)

Calculating the amounts to be used in a pharmaceutical formula to make a smaller amount than the original formula.

Enlarging (Formulas)

Calculating the proper amounts to be used in a pharmaceutical formula to make a larger amount than the original formula.

Factor Method

A method for reducing or enlarging formulas based on the relative quantity of the total formula to be prepared.

Factor Formula

The equation used to determine the scaling factor: $\text{Factor} = \frac{\text{Quantity of formula desired}}{\text{Quantity of formula given}}$.

Ratio and Proportion Method

A mathematical calculation method used to determine unknown ingredient amounts by setting two equal ratios between formula quantities.

Dimensional Analysis Method

A calculation method that uses conversion factors and unit cancellation to solve pharmaceutical formula scaling and dosage problems.

Prescription

Derived from the Latin word "praescriptio" (prae, 'before' and scribo, 'I write'); an order of medication issued by a physician, dentist, veterinarian, or other properly licensed medical practitioner.

Nonprescription Drugs (OTC Drugs)

Over-the-counter medications that may be purchased legally without a prescription.

Prescription Drugs (Legend Drugs)

Medications that may be dispensed legally only on prescription, carrying the manufacturer label warning: "Caution: Federal Law Prohibits Dispensing Without Prescription."

Simple Prescription

A prescription written for a medication that contains only one ingredient.

Compound Prescription

A prescription that contains more than one ingredient and requires mixing by the pharmacist.

e-Prescribing (e-Prescription)

The computer-to-computer transfer of prescription information between authorized prescribers, pharmacies, intermediaries, and payers under nationally accepted standards.

Superscription

The Rx symbol on a prescription, originating from a contraction of the Latin verb "recipe" (meaning 'you take' or 'take thou') and the sign of Jupiter.

Inscription

The principal part or body of the prescription containing the names and quantities of the prescribed medications or ingredients.

Subscription

The dispensing directions given by the prescriber to the pharmacist regarding dosage form, unit quantity, or compounding instructions.

Signa (Signatura)

The directions for the patient transcribed onto the label, indicating dose, frequency, administration route, and special instructions ("mark thou").

Patient Information (Prescription)

The section of a prescription providing the full name, address, age, and weight of the patient for identification and dosing.

Date (Prescription)

The date the prescription was written; controlled substance prescriptions cannot be dispensed or renewed more than 6 months after this date.

Refill Instructions

Prescriber indications regarding whether and how many times a prescription may be refilled; prohibited for Schedule II controlled substances.

Prescriber Information

The section containing the prescriber's signature, name, office address, PRC number, PTR number, and DEA/NPI identifiers.

Schedule I Controlled Substances

Drugs with high potential for abuse and no accepted medical use, such as heroin, marijuana, LSD, peyote, mescaline, and psilocybin.

Schedule II Controlled Substances

Drugs with high potential for abuse and accepted medical use with severe restrictions, such as morphine, codeine, cocaine, oxycodone, and methylphenidate.

Schedule III Controlled Substances

Drugs with moderate or low physical dependence potential, such as mixtures containing limited codeine ($\le 1.8\%$), barbiturate derivatives, and paregoric.

Schedule IV Controlled Substances

Drugs with low potential for abuse relative to Schedule III, such as diazepam, lorazepam, alprazolam, phenobarbital, and flurazepam.

Schedule V Controlled Substances

Drugs with minimal abuse potential containing limited quantities of certain narcotics, widespread in medical use, such as Lomotil.

Physician's Order Sheet

The institutional form used by physicians to write medication orders for hospital inpatients.

Erroneous Prescription

A prescription error where the brand name precedes the generic name, generic name is in parentheses, or brand name is not in parentheses; it is filed and reported to the DOH.

Violative Prescription

A prescription where generic name is missing, illegible while brand is legible, or includes "no substitution"; it is NOT filled, kept, and reported to the DOH.

Impossible Prescription

A prescription where only generic is written but illegible, generic doesn't match brand, both are illegible, or drug is unregistered with FDA; it is NOT filled, kept, and reported to the DOH.

aa. (ana)

Latin abbreviation meaning "of each".

ad

Latin preposition meaning "up to" or "to make".

disp. (dispensatur)

Latin abbreviation meaning "dispense".

div. (dividatur)

Latin abbreviation meaning "divide".

d.t.d. (dentur tales doses)

Latin abbreviation meaning "give of such doses".

ft (fiat)

Latin abbreviation meaning "make".

M. (misce)

Latin abbreviation meaning "mix".

No. (numero)

Abbreviation meaning "number".

non rep. / NR (non repetatur)

Latin abbreviation meaning "do not repeat" (no refills).

q.s. (quantum sufficit)

Latin abbreviation meaning "a sufficient quantity".

q.s. ad

Latin phrase meaning "a sufficient quantity to make".

Sig. (Signa)

Latin instruction meaning "write" (directions on label).

a.c. (ante cibos)

Latin abbreviation meaning "before meals".

ad lib. (ad libitum)

Latin abbreviation meaning "at pleasure" or "freely".

aq. (aqua)

Latin word meaning "water".

b.i.d. (bis in die)

Latin abbreviation meaning "twice a day".

c (cum)

Latin preposition meaning "with".

h.s. (hora somni)

Latin abbreviation meaning "at bedtime".

i.c. (inter cibos)

Latin abbreviation meaning "between meals".

NPO (non per os)

Medical abbreviation meaning "nothing by mouth".

p.c. (post cibos)

Latin abbreviation meaning "after meals".

p.o. / PO (per os)

Latin abbreviation meaning "by mouth" or "orally".

p.r.n. (pro re nata)

Latin abbreviation meaning "as needed" or "if there is need".

q.i.d. (quater in die)

Latin abbreviation meaning "four times a day".

s (sine)

Latin preposition meaning "without".

s.i.d. (semel in die)

Latin abbreviation meaning "once a day".

s.o.s. (si opus sit)

Latin abbreviation meaning "if there is need" or "as needed".

stat. (statim)

Latin abbreviation meaning "immediately".

t.i.d. (ter in die)

Latin abbreviation meaning "three times a day".

ut dict. (ut dictum)

Latin abbreviation meaning "as directed".

APAP

Abbreviation for the medication acetaminophen.

ASA

Abbreviation for acetylsalicylic acid (aspirin).

AZT

Abbreviation for zidovudine.

EES

Abbreviation for erythromycin ethylsuccinate.

HC

Abbreviation for hydrocortisone.

HCTZ

Abbreviation for hydrochlorothiazide.

MTX

Abbreviation for methotrexate.

NSAID

Abbreviation for nonsteroidal anti-inflammatory drug.

NTG

Abbreviation for nitroglycerin.

Afib

Clinical abbreviation for atrial fibrillation.

ADR

Clinical abbreviation for adverse drug reaction.

CAD

Clinical abbreviation for coronary artery disease.

CHF

Clinical abbreviation for congestive heart failure.

COPD

Clinical abbreviation for chronic obstructive pulmonary disease.

GERD

Clinical abbreviation for gastrointestinal reflux disease (gastroesophageal reflux disease).

CRF

Clinical abbreviation for chronic renal failure.

GFR

Clinical abbreviation for glomerular filtration rate.

HRT

Clinical abbreviation for hormone replacement therapy.

HT / HTN

Clinical abbreviation for hypertension.

IOP

Clinical abbreviation for intraocular pressure.

MI

Clinical abbreviation for myocardial ischemia or myocardial infarction.

TPN

Clinical abbreviation for total parenteral nutrition.

URI

Clinical abbreviation for upper respiratory infection.

UTI

Clinical abbreviation for urinary tract infection.

D5W

Abbreviation for dextrose 5% in water intravenous solution.

D5NS

Abbreviation for dextrose 5% in normal saline (0.9% sodium chloride) solution.

D5LR

Abbreviation for dextrose 5% in lactated Ringer's solution.

NS

Abbreviation for normal saline (0.9% sodium chloride) solution.

a.d. (auris dextro)

Latin abbreviation meaning "right ear".

a.s. (auris sinistro)

Latin abbreviation meaning "left ear".

a.u. (auris utro)

Latin abbreviation meaning "each ear" or "both ears".

o.d. (oculo dextro)

Latin abbreviation meaning "right eye".

o.s. (oculo sinistro)

Latin abbreviation meaning "left eye".

o.u. (oculo utro)

Latin abbreviation meaning "each eye" or "both eyes".

CIVI

Abbreviation for continuous 24-hour intravenous infusion.

Metric System (SI)

The International System of Units; an internationally recognized decimal system of weights and measures based on multiples of 10.

Avoirdupois System

A common system of commerce used in pharmacy primarily for measuring bulk weights in manufacturing ($1\,\text{lb} = 16\,\text{oz} = 7000\,\text{grains}$).

Apothecary System

The traditional system of pharmacy developed in England in the 18th century, utilizing historical units for weight and volume.

Grain (Apothecary)

A fundamental unit of weight equal in both Apothecary and Avoirdupois systems ($1\,\text{grain} = 65\,\text{mg} = 0.065\,\text{g}$).

Scruple

An apothecary weight unit equal to 20 grains.

Drachm / Dram (Apothecary)

An apothecary unit of weight equal to 3 scruples or 60 grains.