What is Famotidine?
Famotidine is a drug commonly used to treat gastroesophageal reflux disease (GERD). It is an inhibitor of the H-2 histamine receptor, and influences parietal cells - these are cells in the stomach that secrete the hydrochloric acid that helps to break down food we ingest in the process of digestion.
Therefore, famotidine is used to decrease acid secretion in the stomach, which is useful in treatment of reflux (GERD) and prevention of peptic ulcers [1, 2, 3, 4].
On a molecular level, famotidine works to selectively inhibit enzymes called viral replication proteases papain-like protease (PLpro) and 3-chymotrypsin-like protease (3CLpro), in addition to its effect on the H-2 receptor.
Furthermore, its effect spans beyond the parietal cells - effects on neutrophils and eosinophils (which are cells of the immune system) leading to inhibition of cytokine release were observed [1]. Cytokines are messenger molecules that regulate inflammation. Additionally, famotidine has also been shown to increase bloodflow to the gastric mucosal cells, which may improve the gastrointestinal system's ability to protect itself [5].
When is famotidine treatment indicated?
Famotidine is primarily indicated for diseases that are characterised by excessive acid secretion. These include:
- gastroesophageal reflux disease,
- duodenal and gastric ulcers,
- and Zollinger-Ellison syndrome (which is a disease characterised by multiple tumours growing in the upper gastrointestinal tract leading to excessive acid secretion) [2].
Additionally, recent studies have also demonstrated a potential role of famotidine in COVID-19 treatment, due to the action on the proteases which also play roles in viral replication, in addition to action in reducing clinical symptoms of COVID-19 [1, 6].
Adverse Effects of Famotidine
Famotidine is generally considered very safe and well-tolerated - the overall incidence of side effects ranges from 1-2% [7, 8].
The more common side effects include:
Although not common, serious side effects can occur, including mood problems such as depression or anxiety, seizures, liver damage, thrombocytopenia, heart palpitations, and severe allergic reactions [9]. If any of these side effects occur, it is recommended to seek immediate medical attention.
What are the risks of taking medication in pregnancy?
Taking medication during pregnancy can potentially pose risks for both the mother and the unborn child. Therefore, every case of prescribing medication to a pregnant woman should be considered carefully by healthcare providers.
In-utero exposure to drugs can lead to major malformations of the fetus, birth defects, or even intrauterine fetal death [10]. Additionally, for the mother, physiological changes that occur during pregnancy can affect absorption, distribution, metabolism and elimination of drugs can lead to suboptimal dosing either mitigating the effects or enhancing the effects of the drug to a dangerous level [11, 12].
Additionally, if the drugs are able to cross the placenta, they can exhibit harmful effects on the fetus. However, not all harmful effects of drug exposure are obvious at birth or before, and may manifest later in life [12]. In fact, more than 90% of pregnancies exposed to known teratogens (chemicals harmful to the fetus) result in a normal pregnancy and birth.
However, it is also important to note that only around 1% of all congenital anomalies are a result of exposure to teratogenic drugs [12, 13].
To mitigate this potential impact of a drug on the child during pregnancy, it is needed to consider the risks and benefits for both the mother and the fetus before prescribing medication during pregnancy [14]. Dosing of drugs during pregnancy is often empirically determined and based upon evidence from studies of non-pregnant subjects. Therefore, it is crucial to understand the pharmacokinetics and pharmacodynamics of drugs in pregnant patients [12].
Additionally, communication between the patient and healthcare provider is crucial. Pregnant women should proactively discuss the risks of taking, not taking, stopping or altering the dosage of medication while trying to become pregnant and/or while pregnant [15]. Furthermore, any potential side effects should be discussed immediately.
Is famotidine safe to use during pregnancy?
Famotidine is used widely, especially for treatment of GERD. While it is generally considered safe and well-tolerated, its use during pregnancy needs to be carefully considered. Some people, including people with decreased kidney functions, may not be able to take famotidine [9].
Regarding the use of famotidine in pregnancy, literature agrees that while famotidine is safe, its use needs to be considered on a case-by-case basis and the benefits need to outweigh the potential risks.
A study on over 500 pregnancies examining the impact of H-2 receptor blockers resulted in no increase in birth deffects or major malformations. However, the study did conclude an increased incidence of premature deliveries in the treated group as compared to the control group [16].
Another study concluded that famotidine can cross the placenta and therefore reach the unborn child. However, this was found to not have an adverse effect on the child - the Apgar scores of the children, as well as neonatal gastric acidity or liver function [17].
Additionally, famotidine may also pass into breast milk, however the effects on the child are yet unknown [9].
Summary
Famotidine is generally safe to use during pregnancy. However, every case should be considered on a separate basis, and more research is needed to fully understand the use of famotidine in pregnancy.