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DRUGS IN PREGNANCY Presented By Snigdha Mishra M. Pharm 2 nd sem S.D.P.C. 1


Drugs IN PREGNANCY 2 During pregnancy, the pregnant woman is likely to be exposed to a variety of environmental,nontherapeutic agents which can affect the fetal health.

Pharmacokinetics during pregnancy:

Pharmacokinetics during pregnancy Pregnant woman do not differ qualitatively from the non pregnant ones in their response to drugs, certain alternative differences do occurs because of physiological changes during pregnancy These physiological changes leads to change in pharmacokinetics in drugs ADME Meanwhile the fetus has its own Pharmacokinetic peculiarities 3

Drug Absorption:

Drug Absorption High circulating level of progesterone slows the gastric emptying time as well as gut motility thus increases the intestinal transit time There is slower drug absorption during pregnancy This can be avoided by giving parentral drug administration to obtain quick response 4

Cont……….. :

Cont……….. Administration of iron & antacids may also interfere with absorption of certain drugs Drug compliance may be poor because of nausea & fear of possible adverse effects 5

Drug Distribution:

Drug Distribution Pregnancy is accompanied by an increase in total body water by up to 8 liter & a 30% increase in plasma volume , with consequent decrease in( 0.5- 1.0 gm) in plasma albumin due to Hb The volume of distribution of some drugs increase during pregnancy Dose monitoring is necessary for certain drugs E.g. .Phenytoine – must be adjusted downward 6

Drug Metabolism:

Drug Metabolism Hepatic drug metabolizing enzymes are induced during pregnancy , just because of high circulating enzyme progesterone More rapid metabolic degradation specially of high lipid soluble drugs The metabolism of most such drugs is ordinarily so fast that their clearance is limited only by hepatic blood flow 7

Drug Excretion:

Drug Excretion During pregnancy the renal plasma flow increase by100% & GFR by70% that lead to increase in the unbound fraction of the drug in plasma Drugs which depends for their elimination on kidney are eliminated more rapidly than in non pregnant state E.g.ampicillin, amino glycosides, cephalexin& digoxin 8

Classification of drugs and vaccines:

Classification of drugs and vaccines The Food and Drug Administration (FDA) has developed a rating system to provide therapeutic guidance based on potential benefits and foetal risks . Drugs have been classified into categories A, B, C, D and X based on this system of classification. 9

Cont.. :

Cont.. Drugs, and some multivitamins, that have demonstrated no fetal risks after controlled studies in humans are classified as Category A. On the other hand drugs like thalidomide with proven fetal risks that outweigh all benefits are classified as Category x 10


Cont.. Antibacterial agents Category B : Penicillin, metronidazole, nitrofurantoin, cephalosporins, clindamycin, terbinafine, some microclines e.g. azithromycin, erythromycin Category C : Some aminoglycosides, chloroquine, quinolones, mebendazole, fluconazole Category D : Tetracyclines, gentamicin, tobramycin 11


Cont…. Cardiovascular drugs Category B : Heparin (LMW) Category C : Heparin (conventional), beta-blockers, (dihydropyridine) calcium antagonists, furosemide, digoxin, methyldopa Category D : ACE inhibitors, ARBs, coumarins, thiazides 12


Cont… Central nervous system drugs Category B : Acetaminophen, caffeine Category C : Aspirin, clonidine, rofecoxib Category D : Carbamezapine, valproic acid, diazepam, lithium vaccines Category C : Tetanus toxoid, polio vaccine , BCG vaccine, hepatitis A vaccine, hepatitis B vaccine and rabies vaccine. 13

Harmful effects of drugs in pregnancy:

Harmful effects of drugs in pregnancy These harmful effects depends on the nature of drugs, its dose& route of administration, the stage of pregnancy at which the drug is being used Some genetic constitution & susceptibility of fetus which depends on age, nutritional status& health of mother 14

Gestation may be divided into 4:

Gestation may be divided into 4 (1) Preimlantation (Blastocyte formation) Lasts about 16 days from conception to implantation Exposure to harmful drugs can kill the fetus or damage the fetal growth All or none response 15


Conti… (2) Period of Organogenesis ----- From 17 th to 56 th day after preimplantation phase Both the phases constitutes 1 st trimester of pregnancy Exposure of harmful drugs during this period of organogenesis can cause congenital anomaly, teratogenicity or abortion 16

Cont… :

Cont… (3) The second & third trimester Considerable growth & development occur in teeth, bones, CNS , endocrines , genital & immune system At this stage drug may cause teratogenic or variety of other effects like mental retardation, physical or brain growth Behavioral teratogenicity Pre mature labour 17


Cont… Neonatal toxicity Late postnatal effects such as cancer & tumor (4) Short labour delivery stage- Causes various teratogenic effects 18


Teratogenicity Congenital malformation grossly visible at birth & caused by exposure to exogenous agents in 1 st trimester Any birth defect (morphological , biochemical , or behavioral ) induced at any stage of pregnancy & detected at birth or later phase in life Birth defects are known to occur in 2- 4% of all birth 19


Teratogenicity 20

Cont…. :

Cont…. Out of all the cause is unknown in 65- 70% 25% can be attributed as genetic defects 3% chromosomal disorder Only 3% attributed as environmental factors including maternal infections, radiations & drug administration Fewer than 30 drugs have been proved to be teratogenic in humans at therapeutic dose 21

Certain drugs with proven teratogenic effects:

Certain drugs with proven teratogenic effects Drugs Methotraxate ACE inhibitors Anticholinergic drugs Antithyroid drugs Teratogenic effects CNS& limb malformation Prolong renal failure in neonates, Decrease skull ossification Neonatal meconium ileus Fetal goiter, aplacia 22

Cont.. :

Cont.. Carbamazipines Cyclophosphamides Lithium Phenytoin Tetracycline Thalidomide Valproic acid Neural tube defect CNS malformation cancer Ebestien anomaly Growth retardation Anomaly of teeth & bones Limb shortening Neural tube defect 23

Phocomalia :

Phocomalia 24

Cleft palates:

Cleft palates 25

Drugs prescribing during pregnancy:

Drugs prescribing during pregnancy Treat minor ailments without drugs If prescribed it must be safe for both Adjust the dose Discourage the woman from self medication 26


Cont… Nausea & vomiting---- High carbohydrate diet Antihistaminic, antiemetic ( Cyclizine, meclizine , diphenhydramine) can be prescribed Metochlopromide is safe in 3 rd trimester 27


Cont.., Heart burn ---- Carbohydrate meal Avoid fatty foods, smoking , & alcohols Maintain upright posture Consumption of aerated lemonade 2-3 times a day Nonsystemic antacids Anticholinergic usually worsen the condition by relaxing lower esophageal sphincter 28

Cont… :

Cont… Peptic ulcer— Dietary modifications Non systemic antacids Sucralfate Bismuth subsalicylate is safer Constipation ---- High fiber diet Plenty of liquid Mild laxative ( milk of magnesia) 29

Antimicrobial drugs :

Antimicrobial drugs Beta lactum antibiotics penicillin , cephalosporin's are safe Nitrofurantoin & methanamines are safe Ketoconazole & 5 flu cytosine are safe Amino glycosides are ototoxic To treat severe systemic infection gentamycin & tobramycine is preferred Tetracycline damages fetal teeth & bones 30


Tuberculosis Isoniazide & Ethmbutol are safe Rifampicine should be avoided as far as possible but can be used if a 3 rd drug is needed STREPTOMYCINE Ototoxic to fetus & should never be used in any case during pregnancy 31


NSAIDS Aspirin is non teratogenic but in last trimester of pregnancy it increase gestation time, increases duration of labour Post partum hemorrhage Bleeding in neonate Premature closure of ductus artiosus Pulmonary hypertension in fetus PCM is safer 32


Hypertension Methyldopa is usually safe Beta blockers can cause general retardation ACE inhibitors - abnormality of renal failure & skull development 33

Diabetic mellitus:

Diabetic mellitus Dietary restrictions Insulin No oral Hypoglycemic drugs In insulin dependent diabetics who become pregnant , the insulin requirement drops at 1st trimester then rises progressively 2-3 times to the prepregnancy level up to 36 weeks & then drop again up to term 34


Cont… If diabetes is detected in pregnancy for 1 st time (Gestational diabetes) It is advisable to prescribe a highly purified insulin preparation 35


Epilepsy Phenobarbitone , carbamazipine may be used during pregnancy Dose is adjusted according to severity Phenytoin strictly prohibited Folic acid 5mg per day through the pregnancy Vitamin K1 Routinely for 3 weeks before delivery Valproic acid Contraindicated 36

Drugs acting on CNS:

Drugs acting on CNS Lithium– Teratogenic Opoids – risk of serious CNS depression in fetus Benzodiazepines - Best avoided in end of pregnancy Phenothizines & TCA can be continued at low dose MAO inhibitors are contraindicated 37

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