useful for 2nd pharmd students.

1. PRESCRIBING GUIDELINES FOR PREGNANCY AND LACTATION
Duringthe 40 weeksof pregnancytotal bodywaterisincreasedbyapproximately8liters,leadingto
altereddrugdistribution.Pregnancyalsoincreasescardiacoutput,the rate of livermetabolism,
plasmavolume,glomerularfiltrationandfatstores.These physiological changescause drug
concentrationstobe reducedinpregnancythrougha combinationof haemodilutionandincreased
distribution,metabolismandexcretion.
Pharmacokinetic changes inpregnancy that may require adjustments in
medicationdosing or frequency :
Absorption:
Slowedgastrointestinal motilitymaydelayabsorptionof oral agents.
Renal clearance :
Glomerularfiltrationratesincrease inpregnancyto150% of normal range;manymedicationsthat
are renallyclearedrequire dosage alterationsinpregnancy.Forexample,digoxindosesmayneedto
be increasedtoas much as 1.0 mg bythe endof the secondtrimester.
Hepatic clearance:
An increase inhepaticclearance of pharmacologicagentsisoftenseenduringpregnancy.
Volume of distribution:
Plasmavolume increasesto150% of normal by 24 to 28 weeks’gestation,increasingthe volumeof
distribution.Drugsmayrequire dosage adjustments.
Protein binding :
Dilutionof serumproteins—causedbythe increase infree waterthatisresponsibleformostof the
increase inbloodvolume duringpregnancy—mayleadtoincreasedfree druglevelsforaparticular
total serumlevel.
Safer drugs during Pregnancy
Some medicationsare commonlyusedinpregnancy.
 A dailydose of 400 microgramfolicacid shouldideallybe startedpreconceptuallyand
continuedthroughthe first12 weeksof pregnancytoreduce the riskof neural tube defects.
 Womenwithgastro-oesophagealreflux shouldbe advisedtoeatsmalleramountsof food
more frequentlyandavoidaggravating,richfoods.However,antacidsare oftenrequired
and can be usedat any stage of pregnancy.
 Ferroussulphate iscommonlyprescribedforirondeficiencyanaemiainpregnancybut
alternative saltformulationscanbe triedif there ispoorgastrointestinal tolerance.If the
response tooral treatmentispoorthenwomenmayneed to be referredforparenteral iron.
 Reducedgastrointestinalmotilityinpregnancycanleadtoconstipation.

2.  Lifestyle changesare againfirst-line management,withemphasisonincreasingfluidsand
dietaryfiber.A bulklaxativesuchasispaghulaand/or anosmoticlaxative suchaslacunose
can be safelyprescribed,butstimulantlaxativesshouldbe avoided.
 Penicillin'sandcephalosporin'sare consideredsafe touse inpregnancy.
 Vaginal candidaciesismore commoninpregnancyandcan be treatedwithtopical antifungal
such as clotrimazole,butoral antifungal agentsincludingfluconazole,itraconazole and
terbinafineshouldbe avoided.
 Methldopaissaferantihypertensive druginpregnantwomans.
Antibiotics that canbe usedin pregnancy InfectionSuggestedtreatment :
 Urinary tract infection : Cephalosporin(e.g.cefalexin), Amoxicillin(if sensitive),
Nitrofurantoin(avoidnearterm).
 Acute pyelonephritis :Cephalosporin.
 Co-amoxiclav:ChestinfectionAmoxicillin,Erythromycin.
 Skininfection :Flucloxacillin, PenicillinV, Erythromycin
 Pelvicinflammatorydisease:Erythromycinplusmetronidazole
 Bacterial vaginosis :Metronidazole, Topical clindamycin.
o Paracetamol isconsideredasafe analgesicthroughoutpregnancy.
o For more powerful analgesiaopiatessuchascodeine canbe prescribed,butitshouldbe
rememberedthatif theyare usedtowardstermthentheyrunthe risk of inducingneonatal
respiratorydepressionandwithdrawal syndrome.
o Low dose ibuprofenmaybe the safestoptionbutgenerallyNSAIDsshouldnotbe prescribed.
o Lithiumuse isa particularconcernbecause of the associationwithcongenital cardiac
defects.
o Sodiumcromoglycate eye dropsandnasal corticosteroidscanbe safelyprescribedin
pregnancyforhay fever.
o Chorphenaminehasagood safetyrecordinpregnancyand shouldbe prescribedaheadof
non-sedatingsecondgenerationantihistamines,suchascetirizine,onwhichthere isless
data.
o Womenwithasthmashouldbe stronglyencouragedtocontinue theirmedicationswhen
pregnant.Shortandlong‐actingbeta‐2 agonistsandinhaledsteroidsall appearsafe,
althoughleukotrienereceptorantagonistssuchasmontelukastshouldbe continuedonlyif
theyare essential.Oral steroidsshouldnotbe withheldincasesof severe asthma.
Breastfeeding
A woman'sphysiologyreturnsclose towithinnormal parameterswithindaysof delivery,anddrug
dosesare usuallyreturnedtobaselinewithinthe firstthree daysafterchildbirth.Breastfeeding
providesmanyshortandlongterm benefitstomotherandbaby.Eventhoughmanydrugspass into
breastmilk,feware presentinsufficientquantity tocause anyadverse effects. Some drugsare

3. activelysecretedandconcentratedintobreastmilk(forexample,Phenobarbital),however.Some
drugshave undesirable pharmacodynamiceffectsonthe baby(forexample,iodineinamiodarone
may cause neonatal hypothyroidism,andcytotoxicsmaycause bone marrow suppression),andthe
immature neonatal livermaybe unable tobreakdowndrugs.Drugaccumulationcanhave
undesirableeffectsinthe baby(forexample,benzodiazepinescanleadtodrowsiness).