Drug Therapy during Pregnancy

Abstract

Drug therapy in pregnancy may cause anxiety to both physicians and patients due to uncertainty regarding dosing and safety. Nevertheless, the need for medication is high given that maternal chronic illnesses such as hypertension or diabetes are on the rise 1 . In a national study in the United States over 33 years, the prevalence of prescription medication use by pregnant women in the first trimester increased by 62.5% between the first 2 years of the study and the last 2 years 2 . Furthermore, the average number of medications used anytime in pregnancy has increased two-fold 2 . More recent research from different countries has found that medications are widely used in pregnancy, with the prevalence of using at least one drug ranging from 60 to 90 percent, excluding vitamins and minerals [3][4][5] . Prescription of drugs with potential teratogenicity has also increased in pregnancy, including folate antagonists or angiotensin converting enzyme inhibitors 3,4 . This suggests that many women go into pregnancy with chronic conditions that require medications, including those may pose some degrees of risk to the fetus, since the maternal benefit may outweigh the risk or if the pregnancy is unplanned. Successful treatment of pregnant patients requires a correct diagnosis and providing treatment that not only is effective but also balances risks and benefits, as maternal health is the best defense for fetal health. However, concomitant health conditions, and the intrinsic complex physiological changes associated to pregnancy can make prescribing in this population a particularly challenging balancing act. Very few drugs have specific pregnancy dosing regimens supported by scientific evidence in spite of well-known pharmacokinetics changes during pregnancy affecting a large proportion of medications (Table 1) [6][7][8][9][10] . Data on drug efficacy and safety is sorely lacking for pregnant women, even for drugs that have been available for decades. Pregnant patients are commonly excluded from clinical trials during the drug development process due to ethical and safety concerns, which implies that the majority of drug therapy data in pregnancy have been extrapolated from males and to a much lesser extent, from non-pregnant females 11 . However, using extrapolated data in pregnancy has a number of major drawbacks such as that the extrapolation commonly fails to account for the changes in drug metabolism related to pregnancy 6 . Multiple physiological changes in pregnancy, including those affecting pharmacokinetics, must be considered when prescribing. Furthermore, these changes can also be affected by genetic variability 10 . Some drugs need to be used at higher doses in pregnancy due to increasing metabolic demand. A classic example is thyroid hormone, which requires a 30 to 45 percent higher dose in order to maintain euthyroid state due to limited compensation in pregnant patients with underlying thyroid disease 12 . One of the biggest physiologic changes in pregnancy is the expansion of plasma volume by approximatel...

Pharmacoethics and pregnancy: Overcoming the therapeutic orphan stigma

“…Women prefer to seek information about medication use in pregnancy directly from their healthcare providers. However, the challenge arises when there is lack of evidence‐based data to appropriately display a risk–benefit assessment for the patient to decide 27,32 Database such as LactMed 33 and Reprotox 34 are some of the common resources utilized by clinicians when counselling patients, but these databases can often give inconclusive recommendations given the paucity of evidence available. EUROmediCAT is a consortium that began working in March 2011 and is used to collect and evaluate information regarding the safety of medication use in pregnancy in European countries 35 …”

“…Women prefer to seek information about medication use in pregnancy directly from their healthcare providers. However, the challenge arises when there is lack of evidence-based data to appropriately display a risk-benefit assessment for the patient to decide 27,32 Database such as LactMed 33 and Reprotox 34 are some of When pregnant women are offered the chance to participate in clinical trials, they often have to make the tough decision of participating versus declining because of the pregnancy. In one study interviewing pregnant women who declined participation in a clinical trial assessing prophylactic nifedipine for preterm labour, some of the cited reasons were "protection of the foetus", "feeling like guinea pigs" and "presence of placebo arm".…”