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53
Hospital Formulary System
vi. Frameapolicyforhandlingandsupervisionofdrugscarriedbypatientsfrom
outsideintothehospital.
vii.Evaluate clinicaldata providedby pharmacompany for new drugs or
preparationsmaybeneededforuseinthehospital.
viii. Establishstandardparametersconcerningtheuseandcontrolofdrugs.
ix. Reviewthesuitabilityoftheempiricandtherapeuticuseofdrugsthroughthe
analysisofindividualoraggregatepatternsofdrugpractice.
x. Developmentofpoliciesandproceduresrelatingtotheselection,distribution,
andadministrationofdrugs/diagnosticaids.
xi. ReviewofmonitoringofADRs.
5.Specific drug is added inthe formulary are done on submission of physician’s
requesttotheSecretaryoftheP&TCommittee.Physicians,whomakearequestfor
addition,hastojustifyitsgreatertherapeuticoreconomicvalueincomparisonto
druglistedintheformulary.
7. Requests received for addition within calendar days are generally included in the
meeting agenda of the P&T Committee.
8. Only drugs, listed in the formulary list are stocked in the pharmacy. Physicians are
encouraged accordingly to prescribe the drugs, listed in formulary.
When a non-formulary drug is included in prescription, a pharmacist informs the
prescribing physician that the drug is not available as it is not listed in hospital formulary
list. The pharmacist suggests the physician for listed available alternatives.
However, in special clinical conditions, physician may request for the purchase of a
specific drug if, in his judgment:
• Noneofthecurrentlyavailableformularydrugissuitableforthetherapeuticneed
ofthepatient.
• Allacceptabletherapeuticalternativeslistedintheformularyarefoundunsuccessful.
• Non-formularyproductisbetterincomparisontotheavailablealternatives.
Under these circumstances, non-formulary drug is procured by pharmacy department
from local community pharmacy within 24 hours on getting prescription. Non-formulary
drug is only used by the requesting physician for a specific patient. It is not intended for
use by the other practitioners for the general patient community. Use of non-formulary
drug is documented and record is maintained by the pharmacy.
FORMAT AND APPEARANCE OF THE FORMULARY
Formulary should be good in appearance to attract the staff to use it. Although,
unnecessary expensive decorative artwork is not required but even then, the formulary
should be visually pleasing, easy to read, and professional in appearance.
The need for proper grammar, punctuation, correct spelling, and readable font size
is obvious. There is no standard guideline for the pattern of formulary but typical
formulary must have the following composition:
1. Titlecoverpage.
2. ListofthemembersofP&TCommitteealongwiththeirdesignation.
3. Tableofcontents.
4. Listofhospitalpoliciesandproceduresrelatedtouseofdrugs.
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Textbook of Pharmacy Practice
4.1. P&TCommitteeofhospital.
4.2. Introductiontotheformularysystemmentioningitsobjectives.
4.3. Directionsandproceduresforprescribinganddispensingdrugs.
4.4. Servicesprovidedbyhospitalpharmacy.
4.5. Guidanceforuseofformulary.
5. Pharmaceuticals/drugsacceptedforuseatparticularhospital.
5.1. Listofdrugsaddedanddeletedfromthelastformularyedition.
5.2. Generic-brandnamecrossreferencelist.
5.3. Pharmacological/therapeuticindexwithrelativecostcodes.
5.4. Categorywisepharmacological/therapeuticaldescriptionsofformularydrugs.
6. Supplement
6.1. Listofequipmentsofcentraldepartment.
6.2. Formulasforcalculatingpaediatricdoses.
6.3. Nomographforestimatingbodysurfacearea.
6.4. Scheduleofstandarddrugadministrationtimes.
Several techniques can be used to improve the appearance and ease of use of the
formulary. Among these are:
1. Usingadistinctcolourpaperforeachsectionoftheformulary.
2. Usingamarginindex.
3. Makingtheappropriateformularysize(generally4”×7’’).
4. Differentiatetheprintingofthegenericnameheadingofeachdrugentryfromrest
ofentrybydevelopingtheboldfacetypeorothermethods.
MANAGEMENT OF THE FORMULARY PROCESS
Management of formulary process comprises three main steps as:
1. Formulary process: Formulary process is the keystep for good pharmaceutical
managementandrationaldruguse. Inthis,listofessentialdrugsispreparedor
revisedasstandardtreatmentguidelines(STGs).Selectionofthemostconvenient
therapieswithlowcost-effectiveandhigh-qualitydrugsleadstobetterhealthcare.
TheselectionofdrugstobeincludedinthelistisusuallyaresponsibilityofP&T
Committee,appointedbygoverningbodyofhospital.
Useofdrugas per STGsandstrict adherenceto a formularylisttogetherare
essentialto improvethe healthcare.Furthermore, essential medicines canalso
beused appropriatelyas per the guidelines fordisease management. Ideally,a
formularylistisdevelopedaftertheidentificationordevelopmentofappropriate
treatmentguidelines forcommondiseasesinahospital.Onceaformularylistis
accepted,aformularymanual,providinginformationonlistedmedicinesinthe
formulary,canbecompiled.Figure6.1illustratestheconnectivitybetweenSTGs
andEMLs,whichcanmakeaninfluenceonuseandtheavailabilityofmedicines.
List of essential medicines: These are includedin the formulary list. Essential
medicinessatisfy the most of healthcareneeds of the particularcommunity on
prioritybasis and are available within healthcaresystems roundthe clock in
sufficientnumbers,intheappropriatedosageforms,withcompleteinformation,
andatan affordableprice. Theyareselected on thebasisof disease prevalence,
effectiveness,safetyprofileandcost-factor.Theimplementationoftheconceptof
55
Hospital Formulary System
essentialmedicinesshouldbepurposefulandflexibleandadjustableindifferent
typesofsituations.
Itisdifficulttasktomanageandachieveefficiencyinthehospitalcaresystem
iftoo many numbers of medicinesare available. Drug management, including
procurement,storage,distributionanduse,becomeseasieriffeweritemsarelisted.
Appropriateselectionofdrugscangivethedesiredoutcomeoftreatmentplan.
Criteria for medicine selection: Theselection ofdrugs from thousands of drugs
availablein the market depends ontypes of prevalent diseases, the treatment
facilities,the expertise of available personnel,financial resources,and genetic,
demographicand environmentalfactors. WHO has developed thefollowing
selectionguidelines:
• Onlythosemedicinesshouldbeselectedonthebasisofcompleteclinicaldata
onefficacyandsafety,whichareavailable.
• Each selected medicine must beavailable ina dosage form, whose quality,
includingbioavailability,can be assured. Its stability under the anticipated
conditionsofstorageandusemustbewell-established.
• Whentwoormoremedicines lookssimilarinthepharmacologicalaction,the
selectionbetween them should be madeon thebasis of data related to their
efficacy,safety,quality,costandavailability.
• Incostcomparisonbetweentwomedicines,thetotaltreatmentcostshouldbe
considered,insteadofunitcostofmedicine.Wheredrugsarenotentirelysimilar,
selectionshouldbemadeonthebasisofacost-effectivenessanalysis.
• In some cases, the selection may also be influenced by other factors, suchas
pharmacokineticfactors, or bylocal considerations suchas the availabilityof
storagefacilitiesormanufacturers.
• Most essential medicinesshouldbepreparedassingle ingredient. Fixed-ratio
combinationproductsareacceptableonlywhenthedosageofeachingredient
satisfiestherequirementsofaparticularsocietyandwhenthecombinationis
beneficialincomparisontosinglecompoundsintermsoftherapeuticoutcome,
safetyorcompliance.
• Drugs in the formulary arelisted by the international non-proprietaryname
(INN)or generic name without giving referenceof brandnames or specific
manufacturers.
Fig. 6.1: How STGs and EMLs lead to better prevention and care
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Textbook of Pharmacy Practice
2. Management of a formulary list: Addition and deletion of drugs
Followingstepsaretakenforthisprocess:
i. Requestsforadditionordeletionofadrugtotheformularycanonlybemade
byanattendingphysicianbyfillinguptheprescribedform(Fig.6.2).
ii. Therequestforaddition/deletionformissenttotheSecretary,P&TCommittee,
withacopytosecretory,hospitalformularymanagementsystem.P&TCommittee
makearrangement for evaluation of deletionor additionof drug by the
responsibleperson—eitherclinicalpharmacist,ordruginformationcentrestaff.
iii. P&Tcommitteeconductsaliteraturesearchandpreparesawrittenevaluation
comparingthenewlyrequesteddrugwithcurrentformularydrugsusedforthe
sameindications.Efficacy,safetyandcostarecriteria,whicharetobeconsidered.
iv.TheevaluationisgenerallyreviewedbytheentireFormularyandTherapeutics
Committee.
v. Ifthenewdrugisfoundtobesuperiortoanexistingdrugontheformulary,or
tobeunique,itwillbeaddedtotheformulary.
vi. Existingdrug(s)listedintheformulary,iffoundinferior,andnotrequiredfor
useinotherindications,maybedeletedfromtheformularylist.
vii.Itisrarelyobservedforsendingrequestfordeletionfromtheformularybyastaff
physician.Deletionusuallyoccursduringperiodicclassreviews,orasaresult
ofadversedrugreactionordruguseevaluation.Ifaphysiciansends request
fordeletionofdrug,thecommitteeshouldalsodeterminewhetherdeletionwill
createtherapeuticgapornot.
viii. Newdrugisaddedinthehospitalformularylist,iffoundtohavetobetterefficacy,
safetyor lower cost. Under this circumstance, seriousconsideration should
begiventodeletethedrugfromlistforthesameindication,fortworeasons:
(a)Ifthenewdrugisbetter,whytocontinuewitholddrugonthelist,(b)ifno
effortismadetodeletedrug,nonewillbedeletedandthehospitalformulary
listwillgrowinsizetoincreasethebulk.
Approval of the formulary list for use in the health facility: Thehospitalformulary
listshouldbecompatiblewiththenationalEML,ifthelatterisavailable.Itisvery
importanttofollowthesame previouslyagreedprocessandselectioncriteria at
eachstepinordertoreinforceprescriberconfidenceintheformularylist.
Fig. 6.2: Procedure to add or delete a new medicine
57
Hospital Formulary System
AfterthecompilationoflistofdrugsbyP&TCommittee,aconsentistakento
officiallyapprovethelist,accordingtotheestablishedstrategy.Theformularylist
isthencirculatedtoallphysiciansandpharmacists.Thehospitalchiefphysician
shouldissueaninstructionforcompliancewiththeformularydruglist.Thismay
beannouncedatageneralmeetingofhospitalhealthstaffmembers,togetherwith
theadoptedpoliciesoftheFormularyandTherapeuticsCommittee.Afterthis,the
hospitalcommences to procure only products listed in theformulary list. Non-
formularydrugsmaybeprescribeduntiltheexistingstockisdepleted.
3. Formulary maintenance: Routineevaluationofdifferenttherapeuticcategoriesof
drugsisanimportantcomponentofformularymanagement.Anefficientformulary
managementprocessdoesnotwaitfortherequestforeitheradditionordeletion
ofnewmedicinesintheformularylist.Developmentofnewdrugs/treatmentsis
acontinuousprocessandwithoutevaluationofthese,theformularymaybecome
acollection of old and comparatively lesser effective drugs. Hence, for update,
completeformulary should be reviewed every 2–3 years.This can be achieved
byevaluatingcompletelistedformularydrugswithineachtherapeuticclassina
systematicwayonaregularbasisandcomparingthemtoothernewnon-formulary
medicineswithinthatclass.Thus,inordertoefficientlymanageaformulary,aP&T
committeeshouldmeetregularlytodiscussanddecideupon:
• Requestfortheadditionofnewmedicinesanddeletionofoldandlesseffective
medicines.
• Systematicreviewofeachtherapeuticclassofmedicines.
• Reviewofpoliciestoidentifyandworkoutmedicineuseproblems.
All decisions of the P&T Committee should be documented (as minutes).
Non-formulary drug use: Normally,onlyformularydrugswhichareapprovedand
encouragedtobeusedinahealthcarefacility.However,thetherapeuticneedsofsome
patientsmaynotbefulfilledbyanydruglistedinhospitalformulary.Insuchcases,
theFormularyandTherapeuticsCommittee(or P&T Committee) suggesttheuseof
non-formularydrugby following therecommendedprocedure.Requestsforuseof
non-formularydrugsarealwayssentforaspecificpatient,inanon-FormularyDrug
UseRequestForm,designedandapprovedbycommittee.Formshouldbedulyfilledby
theprescribingphysicianandforwardedittotheinpatientpharmacy,ortheFormulary
andTherapeutics Committee,if thereis noorganized pharmacy department in the
hospital.Itmaybeadvisableforthepharmacisttodiscusstheuseofanon-formulary
drugwithaprescribingphysician. If theprescribingphysician directsandconfirms
therequirementofanon-formulary,thepharmacistsuggeststopurchasethedrugas
requiredinasufficientquantityforthatspecificpatient.TheFormularyandTherapeutics
Committeeshouldreviewall non-formulary drugrequestsonaregularbasis.Ifthe
committeenoticesalargenumberofrequestsforaparticularnon-formularydrug,and
determinesthatitissuperiortoaformularydrug,additionofparticular,anddeletion
ofthelesseffectiveoldformularydrugmaybesuggested.
Role of Pharmacist in Hospital Formulary
1. PharmacistisanimportantandresponsiblepersonintheP&TCommittee,whichhas
akeyroleinframingpoliciesandproceduresinthedevelopmentandmanagement
ofthehospitalformulary.
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Textbook of Pharmacy Practice
2.Chief pharmacist, who is usuallysecretory of P&T committeehas the prime
responsibilityforcompilingthelistofdrugstobeincludedinhospitalformulary.
3. ThepharmacistasamemberofP&Tcommitteeisresponsibleforspecificationsof
quality,quantity,andsourceofsupplyofallmedications,chemicals,biologicals,and
diagnosticpreparationslistedinhospitalformulary.Pharmacistisresponsiblefor
maintainingtheuseofqualitydrugs.Heshouldnotcompromisewiththequality
duetoeconomicalreason.
CONCLUSION
Hospital formulary encourage evidence-based standard practice as drugs are selected
on the basis of their valid clinical safety data.
It ensures the clinically effective, safe and cost-effective prescriptions by identifying
effective and safe medications. It provides impartial drug information to check biased
marketing promotional activities. Formulary process can be one of the most effective
methods of ensuring rational drug therapy and controlling drug cost. It becomes the
cornerstone, if a formulary listed drug is used effectively.
EXERCISE
Multiple ChoiCe Questions
Tick mark the appropriate choice
1. What is listed in the hospital formulary?
(a) Medical equipment (c) Paramedical staff
(b) Medications (d) Intensive care unit patients
2. Which one of these is a part of hospital formulary?
(a) Hospital policies (c) Special information related to therapy
(b) List of drug/its products (d) All of the above
3. The requirement of the hospital formulary system is increasing in present scenario because of
____________
(a) Increase in number of new drugs in market (c) Competition in marketing practice
(b) Increased influence of advertising (d) All of the above
4. What are essential medicines?
(a) List of most effective medicines
(b) Satisfy the healthcare needs of the community on priority
(c) Low-cost medicines
(d) Easily available drugs
short Questions
5. What is hospital formulary system? Mention its advantages.
6. Discuss the role of pharmacist in hospital formulary.
long Questions
7. Discuss the features of hospital formulary in detail.
8. Discuss the procedure for adding and deleting drugs in hospital formulary.
Answer to MCQs
1. (b) 2. (d) 3. (d) 4. (b)
59
Chapter
Therapeutic Drug Monitoring
Therapeutic drug monitoring (TDM) is routine process in clinical practice. It is related
to the analysis of drugs and/or metabolites at a predetermined intervals to determine
their concentration in patient’s blood to know, whether it is within the therapeutic range
or not. It is necessary to maintain the drug concentration in target range. The TDM also
check the concentration of drug, which should be neither subtherapeutic leading to
failure of therapy nor higher, causing potential toxicity.
SIGNIFICANCE OF TDM
• Therapeuticdrugmonitoringisessentialtoindividualizethespecificdosageregimen
forpatients.Itisnecessarytomaintaintheadequatelevelofdrugconcentrationin
patients’blood.
• The efficacyand safety of drugs areensuredby TDM with the maintenance of
concentrationintherapeuticrange.
• PossibilityofADRsispreventedoravoidedbyTDMwiththedeterminationofdrug
concentrationcausingtoxicity,especiallyinchildrenandgeriatricpatients.
NEED FOR TDM
It is easy to adjust the dose to individualize the dosage regimen, when change in clinical
response, such as changes in blood pressure, pain or serum cholesterol can be promptly
measured. TDM becomes essential to avoid the ADRs, when difficult to evaluate clinical
response. For example, it becomes necessary to prevent an adverse consequence like
graft rejection or to avoid toxicity, as with aminoglycosides. There are some criteria for
drug, which require therapeutic drug monitoring. These include:
• Drugs with narrow therapeutic index: Thesearedrugs having smalldifferences
betweentherapeuticandtoxicdoses.
• Pharmacokinetic variability of drugs: Itmeans, these are significant differences
betweenpatientsintheabsorption,distribution,eliminationandmetabolismofadrug.
• TDM is beneficial, when thereis a judicious relationship between plasma drug
concentrationsanditsclinicaleffects.
• Target concentration range:TDMbecomes,whentargetconcentrationisconnected
totheindication.Forexample,therecommendedtargetconcentrationfordigoxin
dependsonwhetheritisprescribedforatrialfibrillationorcongestiveheartfailure.
• Cost-effective drug analysis:Therapeuticdrugmonitoringmaymakebetterdose
managementthat,inturn,maybringdowncostandimproveresult.
7
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Textbook of Pharmacy Practice
Table 7.1 illustrates the examples of some drugs that meet the criteria.
Table 7.1: Drugs that require therapeutic drug monitoring
Drug Target range
Regularly monitored drugs in clinical practice
Digoxin
(indicated in congestive heart failure)
Therapeutic range: 0.5 to 2.0 ng/ml
Toxic digoxin level: > 2.4 ng/ml
Lithium • Acute dementia
• Maintenance dose
Safe blood concentration: 0.6 to 1.2 mEq/L
Toxic level >1.5 mEq/L
0.6 to0.8 mEq/L
Methotrexate
(indicated in Psoriasis, RA, various cancerous
conditions, non-Hodgkin lymphomas, etc.)
10 to 25 mg/ weekly
Phenytoin
(Indicated in the treatment of epilepsy)
Initial dose: 100 mg 3 times a day or 300 mg once
a day.
Cyclosporine
(prevent rejection of transplanted organs,
autoimmune disorders)
50–125 mg/L
150–400 mg/L (whole blood)
Sirolimus 5–15 mg/L (whole blood)
Tacrolimus 5–20 mg/L (whole blood)
Drugs for which TDM may be beneficial
Amiodarone
(indicated in arrhythmias)
1 to 2.5 mg/L
Carbamazepine
(indicated in the treatment of epilepsy)
5 to 12 mg/L
Flecainide
(indicated in arrhythmias)
0.2 to 0.9 mg/L
Lamotrigine
(indicated in the treatment of epilepsy)
1.5 to 3 mg/L
Salicylate
(indicated in cardiac stroke)
150 to 300 mg/L
Sodium valproate
(indicated in the treatment of epilepsy)
50 to 100 mg/L
Vancomycin
(indicated in bacterial infections, resistant to less
toxic antibiotics)
Adult dose: 125 mg, 4 times a day for 10 days
FACTORS AFFECTING THE RESULT OF TDM
1. Patient characteristics: These include patient’s age, gender,body weightand
ethnicity, which should be consideredin interpretingTDM results.Age, sex and
bodyweightaresignificantlyimportantforrenallyeliminateddrugs.Knowledgeof
theseisadvantageousininterpretationofsomeparameterslikecreatinineclearance.
EthnicitymaybeanimportantforTDMofsomehepaticallymetaboliseddrugs.For
example,thevariationsinimmunosuppressivedrugpharmacokineticsareattributed
tointerindividualfunctionalactivityvariationsofcytochromeP
450
enzymesintheliver.
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Therapeutic Drug Monitoring
2. Patient compliance: Subtherapeutic dose, if administered, may be considered
patientnon-compliancebeforeatherapeuticdoseisrecommended.Thesimplest
waytoknowthenon-complianceistoenquirefromthepatientinapolitemanner.
However,insomeconditions,itisnotareliablemethod,especiallyafterepileptic
attack,whenpatientisconfused.
3. Pharmacokinetic variations:Pharmacokineticsisthestudyofwhatthebodydoes
toadrugafteradministration.Itincludestheobservationsunderfourcategories—
absorption,distribution,metabolismandexcretionofdruginthebody.Theseare
majorpharmacokineticscomponentsaffectingdrugconcentration.
Some factors which influence pharmacokinetic parameters are:
• Age: In general, drugs are metabolized slowly in foetal,neonatal, and aged
communities.
• Physicalpropertiesofthedrug,whichincludehydrophobicity,pKa,solubility
• Timingofthedrugadministered(afterfoodorinfastedstate)
• Gastricemptyingrateaffectthepharmacokineticparameters,forexample,increase
ingastricemptyingrate,enhancestherateofabsorptionofadrug.
• Interactionswithotherdrugs.Enzymeinducingdrugslikephenytoin,barbiturates,
carbamazepine,glutethimide,rifampicininducestheenzymestoincreaserateof
metabolismofdrugstoreducethedrug'sactivity.Enzymeinhibitingdrugs,such
asnitrogenmustard,proteaseinhibitorscausedecreaseinrateofmetabolism),
resultingindecreaseddrugactivity.Intakeofantacids,alcohol,nicotinealong
withmaindrugmayalsoaffectthepharmacokineticparameters.
4. Genetic factors:Pharmacokinetic parametersare affectedby genetic factors to
causeimpactintherapeuticdrugmonitoring.Forexample,antituberculoticdrug,
isoniazidismetabolizedbyenzymaticacetylationreaction.Pooracetylatingcapacity
ofenzymesinsomeracescausehepatotoxicityduetogeneticvariation.
5. Concurrent disease, tropical disease and undernutrition condition: Poorhealth
canalsoinfluencetheTDMindevelopingcountries.Poorhealthinthesecountries
maybeduetoinfectiousdiseases,diarrhoea,worminfestations,tuberculosis,and
nutritionalinsufficiencies,plusamorenumbersofdiabeticandAIDSpatients.The
rateofdrugclearanceofdrugismodifiedbyacuteorchronicdiseasemodifies.Thus,
drugconcentrationlevelmaybechanged,eitherelevatedordecreaseddepending
onthe pathophysiology of the systemimplicated, e.g. liver disorder diminishes
theconversion to morewater-soluble compound to decreasethe clearance of
drugs.Changesinpharmacokineticparametersarealsoobservedinpatientswith
congestiveheart failure.Decreased in blood flowto liver and kidney results in
diminisheddrugclearanceincongestive heart failureassociatedwithdecreased
hepaticmetabolizingactivity.
Nutritionalinsufficiencieshavealsobeenreportedtoaffectdrugpharmacokinetics.
6. Use of complementary medicine: Ayurveda,homeopathyandunanisystemare
predominantthreesystems of medicine,followed inIndia. These arecoexisting
withallopathic system (British system). Some allopathic practitionersoften
prescribecomplementary medicinefrom alternativesystem of medicine along
withallopathicmedicine,particularlyforchronicdisorders.Forexample,during
TDM,an interaction of ‘shankhpushpi’, an ayurvedic medicinewith phenytoin
(anantiepilepticdrug),hasbeenidentified.Shankhpushpi(Convolvulus prostratus)
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Textbook of Pharmacy Practice
isusedasamemoryenhancerinayurvedicsystemofmedicine.Apatientwitha
historyofgeneralizedtonic-clonic(GTC)seizures,wellcontrolledwithphenytoin,
presentedwithsuddenlossofseizurecontrolduetointakeof‘shankhpushpi’.Itwas
identifiedduetoloweringofbloodphenytoinlevelandduetobothpharmacokinetic
andpharmacodynamicinteraction.
7. Races differences and hypothesizing the normal range of drug: Drug
pharmacokinetic variations in inter-populationscan resultin either elevated or
decreasedplasmadrugconcentrations.Forexample,para-hydroxylationmetabolic
reactionissubjecttowideinterpopulationvariationincaseofphenytoindrug.It
hasbeenreportedthattheeffectiveanticonvulsantdosagemaybelowerinIndians
incomparisontoEuropeansduetosignificantinfluenceontheplasmaclearanceof
phenytoin.
8. Practice of drinking alcohol and smoking:Chronicuseofalcoholhasbeenindicated
tocausenon-specifichepaticmicrosomalenzymeinduction,whichleadstoincreased
clearanceofhepatically eliminated drugs,e.g.phenytoin.It resultsindecreased
serumconcentrations.
Thehepaticeliminationoftheophyllineisenhancedincaseofsmokingandhence,
surprisinglyhightheophyllineconcentrationhasbeenobservedinthepatientwho
hasrecentlystoppedsmoking.
9. Quality of medication and unbranded (generic) formulation: Worldwideuseof
genericproductsisincreasing,activelypromotedbyhealthauthoritiesforeconomic
reasons.Hence, numberof prescriptionshaving generics medicines, issued by
primarycarephysicianshasrisenindevelopingcountries.Theremaybevariations
indrug quality amongvarious genericproducts.Quality of products(e.g. drug
content,bioavailability)becomesquitesignificant,especiallyfordrugswithanarrow
therapeuticindex.
10.Control of drug assay: Qualitycontrolremainsoneofthemostessentialtasksfor
theclinicallaboratorytoensurethereliabilityandaccuracyofreportedpatientTDM
results.Theresultssenttophysiciansneedtobecorrectedbeforefinalconclusion,
hencecompleteprocedureofTDMshouldbevalidatedinaccreditedlaboratoryfor
validationofresult.
11.Error in selection of sample: The possibilityof medication or sampling errors
orerrors shouldnot be ruled out, when the TDMresult differs fromthe drug
administrationrecords. For example, there is a lapse indrug administrationin
patientsor blood may have been mistakenly drawn froma patient lying on a
neighbouringbed.
12.Laboratory errors: The manager of the laboratory should be contactedand
askedtorepeattheprocedurerelatedtoqualitycontrol,ifreportissuspicious.
Alternatively,afreshbloodsamplecanbedrawnandsenttoanotherlaboratory
forassay.
13.Cost effectiveness: Rapidandcost-effectiveanalysisofdrugsforwhichTDMis
beneficial,canbedonebyusingcommercialkitsrunorautomatedanalysers.
Chromatographicandultrafiltrationtechniquestakelongtimeandrequirehighly
skilledstaff.Itbecomesmorecost-effective,whenqualitycontrolprocedureisdone
inlimitednumberofcentresofexcellencewithsuitablyqualifiedtechniciansand
stringentqualityassurance.