Australian Drug Categories

Introduction

Legal drugs are classified, usually by each country's appropriate regulatory body, on the safety of drugs during pregnancy. In Australia, the Therapeutic Goods Authority has classes (A, B1, B2, B3, C, D and X) to define their safety. In the USA, drugs are classified by the Food and Drug Administration (FDA) into classes (A, B, C, D, and X) to define their safety.

The example drugs given on this current page are from Prescribing medicines in pregnancy.

The placenta and fetal tissues may also deal with drugs differently from adult target tissues. In particular, drugs are "cleared", metabolised and excreted, at a different (lower) rate in both the fetus and in newborn infants.

Links: Australian Drug Categories | USA Drug Categories | Human Abnormal Development | 2010 BGD Phase 2 Tutorial - Applied Embryology and Teratology | Prescribing medicines in pregnancy, 4th edition | Original Drugs Page

Pregnancy Category A

Have been taken by a large number of pregnant women and women of childbearing age without an increase in the frequency of malformations or other direct or indirect harmful effects on the fetus having been observed.

Pregnancy Category B1

Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have not shown evidence of an increased occurrence of fetal damage.

Pregnancy Category B2

Have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals are inadequate or may be lacking, but available data show no evidence of an increased occurrence of fetal damage.

Pregnancy Category B3

Have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have shown evidence of an increased occurrence of fetal damage, the significance of which is considered uncertain in humans.

Pregnancy Category C

Have caused or may be suspected of causing, harmful effects on the human fetus or neonate without causing malformations. These effects may be reversible.

Pregnancy Category D

Have caused, are suspected to have caused or may be expected to cause, an increased incidence of human fetal malformations or irreversible damage. These drugs may also have adverse pharmacological effects.

Examples: Angiotensin converting enzyme (ACE) inhibitors (captopril, cilazapril, enalapril, fosinopril, lisinopril, perindopril, quinapril, ramipril, trandolapril), Angiotensin II receptor antagonists (ARAs) (candesartan cilexetil, eprosartan, irbesartan, losartan, valsartan), Anticonvulsants / Antiepileptics (carbamazepine, phenytoin sodium, methylphenobarbitone, phenobarbitone, primidone, sodium valproate (valproic acid), lamotrigine, ethosuximide, methsuximide, phensuximide, sulthiame, vigabatrin), Antirheumatoid agents (hydroxychloroquine), Muscle relaxants (quinine), Endocrine system (estrogens conjugated, Dydrogesterone, hydroxyprogesterone, megestrol, norethisterone, Fluoxymesterone, methenolone, nandrolone, oxandrolone, oxymetholone, testosterone, Nafarelin, goserelin, Aminoglutethimide, Danazol, Gestrinone), Antimicrobials (Tetracyclines Demeclocycline, doxycycline, minocycline, tetracycline)

Pregnancy Category X

Have such a high risk of causing permanent damage to the fetus that they should NOT be used in pregnancy or when there is a possibility of pregnancy.

Examples: Misoprostol, Dienoestrol, Raloxifene, Finasteride, Ribavirin, Tretinoin (Oral), Isotretinoin, sodium phosphate P³²

References

Search PubMed: Australian Drug Categories | Drug Categories | teratogenic drugs

Links: Abnormal Development - Drugs | Australian Fetal Risk Categories | USA FDA Fetal Risk Categories | Therapeutic Goods Authority | Australian Drug Evaluation Committee (ADEC) | Prescribing Medicines in Pregnancy | Appendix A: Therapeutic goods exempted from pregnancy classification |

Glossary Links

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Cite this page: Hill, M.A. (2024, May 5) Embryology Australian Drug Categories. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Australian_Drug_Categories

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G