Oral Med and Drug Calc.

7/24/2019 Oral Med and Drug Calc.

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Drug Calculations: Systems of Measurement

Converting Within the Metric System

The metric system is most commonly used for medication administration. Since itis organized in units of 10, you can easily convert to the dierent unit ofmeasurement by multiplying or dividing by 10, or by moving the decimal to theright or left.

Basic units of measurement include:

iter: !olume

"ram: #eight

$eter: ength

The follo%ing table sho%s common pre&'es for subdivisions or multiples of thebasic unit.

Prefix

Micro (mcg)

Milli (m)

Milli (m)

kilo (k)

Milli (m)

Centi

(ommon (onversions

#eight

o 1,000 mcg ) 1 mg

o 1,000 mg ) 1 g

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o 1,000 g ) 1 *g

!olume

o 1,000 m ) 1

ength

o 1 cm ) 10 mm

Converting From Household to Metric

Converting Pounds to Kilograms

$edications may be ordered based on your client+s %eight, and doses arecalculated according to the client+s %eight in *g. Since client+s %eights are oftenrecorded in pounds lb-, you must convert pounds to *ilograms *g-. To do this,

remember that 1 lb ) . *g.

Therefore, if a client %eighs 0 lb, you %ould divide the %eight in lb by .*g/lb:

Converting Ounces to Milliliters

Since most liuids in the nited States are delivered in 2uid ounces, ounces oz-

often must be converted to milliliters m- in the clinical arena. To do this,remember that 1 oz ) 30 m.

Therefore, if a client dran* an 4 oz bottle of %ater, you %ould multiply the volumein oz by 30 m/oz:

4 oz ' 30 m/oz ) 50 m

6rug (alculations: 7ormula $ethod

The formula method for calculating drug dosages is simple and easy toremember.

6 ) 6esired dose dose ordered-8 ) 6ose on hand dose available-! ) !ehicle form in %hich the drug is available: tablet, capsule, or liuid-


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Therefore, if an order for 9cetaminophen is 1,000 mg, and you have 00 mgtablets on hand, you %ould divide the order by the mg/tablet to &nd the correct

dose:

6rug (alculations: ;atio and ) tablets

6rug (alculations: 7ractional ?uation $ethod

The fractional euation method is similar to the ratio and proportion method,e'cept it is set up as a fraction in the euation.

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6 ) 6esired dose dose ordered-8 ) 6ose on hand dose available-! ) !ehicle form in %hich the drug is available: tablet, capsule, or liuid-

Solve for > by cross@multiplying

8X) 6!

Therefore, if an order for 9cetaminophen is 1,000 mg, and you have 00 mgtablets on hand, you %ould solve for Xby cross@multiplying:

X) tablets

6rug (alculations: 6imensional 9nalysis

6imensional analysis involves the conversion of a uantity in one unit to adierent unit of measurement by cancelling eual units of measurement. 7orinstance, if you have a medication ordered in milligrams but it is delivered inmicrograms, the conversion process is %ithin one formula.

6 ) 6esired dose dose ordered-8 ) 6ose on hand dose available-! ) !ehicle form in %hich the drug is available: tablet, capsule, or liuid-( ) (onversion factor

Therefore, if an order for 9cetaminophen is 1 g conversion factor: 1 g ) 1,000mg-, and you have 00 mg tablets on hand, you %ould establish the dose by:

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X) tablets

$edication 9dministration: egal 9spects

9s the nurse, you are legally responsible for the administration of medications tothe client. The health care provider $edical 6octor $6- or Aurse


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Types of medication orders include:

$edication orders are %ritten or computerized.

#ritten orders are recorded in the client+s chart.

Telephone orders are recorded by the nurse and classi&ed as a telephone

order in the client+s chartE they must be signed by the prescriber %ithin 5hr.

$edication orders are %ritten as follo%s: one time only, prn as needed-,

or routine according to the prescriber+s instructions until the order iscancelled-.

;ights of medication administration include:

1. ;ight medication

. ;ight dose

3. ;ight client

5. ;ight route

. ;ight time

F. ;ight reason

G. ;ight documentation

$edication 9dministration: =ral, Sublingual, and Buccal ;outes

Oral medications:=ral medications are administered by mouth %ith absorptionoccurring in the gastrointestinal "- tract. =ral forms of medications includetablets, capsules, and liuids.

=ral medications are also administered through nasogastric and gastrostomytubes. The procedure is as follo%s:


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9dminister medications in eli'ir form %hen availableE if not, crush tablets

to a &ne po%der and mi' %ith tap %aterE do not crush or administersustained release or enteric@coated medications.

7or client+s receiving enteral feeding, be sure the enteral feeding is

compatible %ith the medications. f not, stop the feeding for 30 to F0 min

before and after administration.

f the tube is connected to intermittent or continuous suction, stop the

suction for 30 min after medication administration.

7lush the enteral tube %ith 30 m of tap %ater follo%ing medication

administration.

Sustained release oral medications:These medications are manufactured todelay absorption. They are used to slo% drug absorption in a controlled manner.#hen administering these medications, do not crush or brea* the medication.

This %ill impair the preparation, its dosage, and the client+s response.

Sublingual medications: Sublingual medicationsare placed under the tongueand absorbed through the mucous membrane of the mouth into the bloodvessels for rapid onset of action. Sublingual medications bypass thegastrointestinal tract and the liver to eliminate the &rst@pass loss %hen drugs aremetabolized before reaching the site of action.

uccal medications: Buccal medicationsare held against the mucousmembrane bet%een the chee* and teeth. They are absorbed through the mucousmembranes of the mouth. The absorption of buccal medications is the same assublingual. They bypass the gastrointestinal tract and the liver.

$edication 9dministration: Topical $edications: ;ectal, rrigations,Transdermal, and nhalation

Topical medications are applied to the s*in, body cavities, eye, ear, or respiratorytract and are administered by the follo%ing methods: irrigations, transdermal,inhalation, or instillation ophthalmic, otic, and nasal medications-. Theformulations of the medications are lotions, creams, ointments, solutions,po%ders, and patches. They are never ingested.

!ectal

;ectal administration is a convenient and safe method for giving somemedications.

"rrigations

rrigations are applied to body cavities, such as the urinary bladder or vagina.rrigations may instill pharmacologic agents or merely cleanse the ori&ce.

#ransdermal

G
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The application of the medication is designed to provide slo% release of the drug,usually by a patch. ?'amples of these medications include nitroglycerine,fentanyl, estrogen,and nicotine.

"nhalation

nhaled preparations are administered into the respiratory tract using a mist,spray, or positive pressure.

$edication 9dministration: Topical $edications: ;ectal, rrigations,Transdermal, and nhalation

=ther topical medication administration methods include the follo%ing:

O$hthalmic:These medications are administered into the eye as drops orointments.

Otic:These medications are administered into the ear as drops. The clientis instructed to lie on the unaected ear for several minutes to ensure themedication stays in the aected ear.

%asal:$edications are administered in the nose to produce local or

systemic eects.

$edication 9dministration:


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ntradermal inIections are administered into the dermal layer of the s*in, Iustunder the

$edication 9dministration:


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Aursing


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Chemical name:identi&es the drug+s atomic and molecular structure. t

utilizes e'act chemical language and terminology.

'eneric name:identi&es the drug+s active ingredient and is the assigned

name from the manufacturer %ho developed the drug.

O(cial name:the name used in oNcial publications such as the Lnited

States


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#o,ic e*ects:harmful eects on the body, usually the result of a drug

overdose, ingestion of a drug intended for e'ternal use, or cumulativeeects resulting from impaired e'cretion or metabolism.

"diosyncratic e*ect:an une'pected eect. t is an individual response to

a drug manifested as an underresponse, overresponse, or completely

dierent response.

+llergic reaction:a client+s immunologic reaction to a drug. 9 client can

react to a drug by producing antibodies, Iust as it does any other time thebody reacts to a foreign substance. The reaction can range from a mildrash to an anaphylactic reaction.

Drug interactions:#hen t%o drugs are given at the same time, one orboth may alter the eect of the other. The eect may be increasedpotentiating eect- or decreased inhibiting eect-.


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iotransformation

9lso *no%n as metabolism

The drug is changed from its original form to a ne% form.

The primary organ of biotransformation is the liver. The liver possesses

many drug@metabolizing enzymes.

The products of drug metabolism are active and inactive metabolites. 9n

active metabolite has a pharmacologic action, and an inactive metabolitehas no pharmacologic action.

Biotransformation is altered %ith hepatic insuNciency and in young and

older clients. To ensure the drug is metabolized in the body, it is importantto *no% the client+s alanine aminotransferase 9T-andaspartateaminotransferase 9ST-levels. ?levations in liver enzymes are indicative

of impaired liver function.

.,cretion

6rugs and metabolites are e'creted primarily in the *idneys and are

eliminated in the urine.

=ther sites of e'cretion include feces, e'haled respirations, perspiration,

saliva, and breast mil*.

To ensure that drugs and metabolites %ill be properly e'creted, it is

important to *no% the client+s blood urea nitrogen BA-and serum

creatinine levels. ?levated levels indicate impaired renal function.


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9gonist: 6rugs that bind to the receptor site and cause the same response

as a physiologic or endogenoussubstance.

9ntagonist: 6rugs that bind to the receptor site and inhibit cell function.


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Oral Med and Drug Calc.

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