Drugs in pregnancy
Encyclopedia
Drugs used during pregnancy can have temporary or permanent effects on the fetus. Any drug
that acts during embryonic or fetal development to produce a permanent alteration of form or function is known as a teratogen.
(acetaminophen) is generally associated with lower risk than the fever itself. Similarly, diabetes mellitus during pregnancy may need intensive therapy with insulin to prevent complications to mother and baby.
to implantation of the fertilized egg
is called preimplantation period. This is an 'all or none' period, .i.e. an insult can either cause death or complete recovery.
The period from the 8th day to the end of 8th week (2nd month) is the period of organogenesis
during which the organs are formed in the fetus. This is the most crucial time with regard to 'structural malformations' and concern over teratogenicity of drugs. From the 3rd month week to the end of 9 months is the period of fetal maturation. Intake of drugs during this period may modify the 'function' of the fetal organs rather than causing gross structural malformations in the fetus, for example, aminoglycosides can affect the functioning of kidneys and also the hearing mechanism.
(FDA) has developed a rating system to provide therapeutic guidance based on potential benefits and fetal risks
. Drugs have been classified into categories A, B, C, D and X based on this system of classification. Drugs like 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.
Cardiovascular drugs
Central nervous system drugs
Vaccines
Drug
A drug, broadly speaking, is any substance that, when absorbed into the body of a living organism, alters normal bodily function. There is no single, precise definition, as there are different meanings in drug control law, government regulations, medicine, and colloquial usage.In pharmacology, a...
that acts during embryonic or fetal development to produce a permanent alteration of form or function is known as a teratogen.
Prescribing for the pregnant woman
Many physicians would prefer not to prescribe for pregnant women, the major concern being over teratogenicity of the drugs. The apprehension is not necessarily data driven and is mostly due to lack of clinical studies in pregnant women. This can result in inappropriate treatment of pregnant women and fetus. Use of drugs in pregnancy is not always wrong. For example, high fever is harmful for the fetus in the early months, thus the use of paracetamolParacetamol
Paracetamol INN , or acetaminophen USAN , is a widely used over-the-counter analgesic and antipyretic . It is commonly used for the relief of headaches and other minor aches and pains and is a major ingredient in numerous cold and flu remedies...
(acetaminophen) is generally associated with lower risk than the fever itself. Similarly, diabetes mellitus during pregnancy may need intensive therapy with insulin to prevent complications to mother and baby.
Period of drug use
Pregnancy and development of fetus progresses through various changes. The period of one week from fertilisationFertilisation
Fertilisation is the fusion of gametes to produce a new organism. In animals, the process involves the fusion of an ovum with a sperm, which eventually leads to the development of an embryo...
to implantation of the fertilized egg
Zygote
A zygote , or zygocyte, is the initial cell formed when two gamete cells are joined by means of sexual reproduction. In multicellular organisms, it is the earliest developmental stage of the embryo...
is called preimplantation period. This is an 'all or none' period, .i.e. an insult can either cause death or complete recovery.
The period from the 8th day to the end of 8th week (2nd month) is the period of organogenesis
Organogenesis
In animal development, organogenesis is the process by which the ectoderm, endoderm, and mesoderm develop into the internal organs of the organism. Internal organs initiate development in humans within the 3rd to 8th weeks in utero...
during which the organs are formed in the fetus. This is the most crucial time with regard to 'structural malformations' and concern over teratogenicity of drugs. From the 3rd month week to the end of 9 months is the period of fetal maturation. Intake of drugs during this period may modify the 'function' of the fetal organs rather than causing gross structural malformations in the fetus, for example, aminoglycosides can affect the functioning of kidneys and also the hearing mechanism.
Categories of drugs
The Food and Drug AdministrationFood and Drug Administration
The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...
(FDA) has developed a rating system to provide therapeutic guidance based on potential benefits and fetal risks
Pregnancy category
The pregnancy category of a pharmaceutical agent is an assessment of the risk of fetal injury due to the pharmaceutical, if it is used as directed by the mother during pregnancy. It does not include any risks conferred by pharmaceutical agents or their metabolites that are present in breast...
. Drugs have been classified into categories A, B, C, D and X based on this system of classification. Drugs like 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.
Classification of a few important drugs/vaccines
Antibacterial agents- Category B : Penicillin, metronidazole, nitrofurantoin, cephalosporins, clindamycin, terbinafine, some macrolides e.g. azithromycin, erythromycin
- Category C : Some aminoglycosides, chloroquine, quinolones, mebendazole, fluconazole
- Category D : Tetracyclines, gentamicin, tobramycin
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, diltiazem
Central nervous system drugs
- Category B : Acetaminophen, caffeineCaffeineCaffeine is a bitter, white crystalline xanthine alkaloid that acts as a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants...
- 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.