Australian Drug Categories

Introduction

Therapeutic Goods Administration logo.

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 (TGA) has classes (A, B1, B2, B3, C, D and X) to define legal drugs safety.

The original Australian Drug Evaluation Committee (ADEC) formed in 1963 was replaced in 2010 by the Advisory Committee on Prescription Medicines (ACPM).

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. (More? USA Drug Categories)

The drug examples given on this current page are not a comprehensive list within the drug classification, and are derived from Prescribing medicines in pregnancy.^[1]

This page also includes a brief generic description of current drug testing procedures.

Links: Australian Drug Categories | USA Drug Categories | Human Abnormal Development | Medicine BGD2 Tutorial - Applied Embryology and Teratology

Pregnancy Category

Australian Drug Categories
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. (More? Australian Drug Categories) 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. 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. Abnormal Development - Drugs

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

Drug Testing

Typical testing of new drug compound today involves a lengthy series of animal and human studies.

Animal Studies

Usually tested in at least two mammalian species (rats and guinea pigs) using both single and repeated doses. For determining reproductive effects, tests on both male and female animals with dosing begins 4 weeks prior to mating are conducted to determine effects on fertility in both sexes, on embryogenesis, and on fetal malformation.

Human Clinical Trials

Following animal studies to determine dose, efficacy and apparent safety, human studies can commence. Clinical trials are carried out under very strict conditions, set by international regulatory bodies in agreement with the principles espoused in the Declaration of Helsinki. There are four phases to the trials.

Phase I trials - conducted in small groups of 10 to 20 healthy young male volunteers. Designed to examine how the drug is absorbed, distributed, metabolised and excreted by the body and to establish the safe dose for phase II trials.
Phase II trials - conducted in 50 to 100 patients with the disease rather than healthy volunteers as in phase I. Designed to examine what effect the drug has on the body (heart rate, blood pressure and cognitive effects) depending on the disease the drug is being developed to treat.
Phase III trials - conducted in 100’s of patients (larger numbers) with a particular disease or condition and are generally randomised comparative double-blinded studies. Using a comparator of either placebo, another active drug already used, or both. Several phase III trials are usually required by the regulatory authorities. Note that even these studies may not identify uncommon adverse effects, until used widely in the community.
Phase IV trials - (post-registration) conducted in 1000’s of patients over several years, these trials are randomised controlled trials undertaken after the drug has been registered.

Government Regulatory Authorities

After phase I to III the pharmaceutical company compiles all study data for independent assessment by government regulatory authorities in each country:

Australia - Therapeutic Goods Administration (TGA)
Canada - Health Products and Food Branch (HPFB)
New Zealand - Medsafe in New Zealand
UK - Medicines & Healthcare products Regulatory Agency (MHRA)
USA - FDA

Declaration of Helsinki
The Declaration of Helsinki was developed by The World Medical Association (WMA) as a statement of ethical principles for medical research involving human subjects, including research on identifiable human material and data. The Declaration is intended to be read as a whole and each of its constituent paragraphs should not be applied without consideration of all other relevant paragraphs. It is widely regarded as the cornerstone document on human research ethics. It is named after the location of its initial adoption in Helsinki, Finland, in June 1964.

Australia - Advisory Committee on Prescription Medicines

The Australian Drug Evaluation Committee (ADEC) was established in 1963 following the thalidomide experience and in 2010 this committee was replaced by the Advisory Committee on Prescription Medicines (ACPM). The new ACPM advises and makes recommendations to the Therapeutic Goods Administration (TGA) on prescription medicines listed on the Australian Register of Therapeutic Goods (ARTG), established under the Therapeutic Goods Act 1989. There were approximately 54,000 products on the Australian Register of Therapeutic Goods as at 23 May 2008.

Advisory Committee on Prescription Medicines

inclusion of a prescription medicine on the Australian Register of Therapeutic Goods (the Register)
changes to an entry of a prescription medicine on the Register
removal or retention of a prescription medicine on the Register

Links: Advisory Committee on Prescription Medicines

Additional Notes

Many herbal, illegal and recreational drugs do not fall into the above classifications and information about the affects on development can be found in research literature and in medical literature prepared for the general public.
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.

References

↑ Prescribing medicines in pregnancy, 4th edition

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

External Links

External Links Notice - The dynamic nature of the internet may mean that some of these listed links may no longer function. If the link no longer works search the web with the link text or name. Links to any external commercial sites are provided for information purposes only and should never be considered an endorsement. UNSW Embryology is provided as an educational resource with no clinical information or commercial affiliation.

Australia Therapeutic Goods Authority
USA TOXNET - Databases on toxicology, hazardous chemicals, environmental health, and toxic releases. mobile

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2024, April 19) Embryology Australian Drug Categories. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Australian_Drug_Categories

What Links Here?

[1] Prescribing medicines in pregnancy, 4th edition

[1]