Pharmacokinetics of cefoperazone in the parturient

Pregnancy-Associated Changes in Pharmacokinetics: A Systematic Review

BACKGROUND

Women are commonly prescribed a variety of medications during pregnancy. As most organ systems are affected by the substantial anatomical and physiological changes that occur during pregnancy, it is expected that pharmacokinetics (PK) (absorption, distribution, metabolism, and excretion of drugs) would also be affected in ways that may necessitate changes in dosing schedules. The objective of this study was to systematically identify existing clinically relevant evidence on PK changes during pregnancy.

METHODS AND FINDINGS

Systematic searches were conducted in MEDLINE (Ovid), Embase (Ovid), Cochrane Central Register of Controlled Trials (Ovid), and Web of Science (Thomson Reuters), from database inception to August 31, 2015. An update of the search from September 1, 2015, to May 20, 2016, was performed, and relevant data were added to the present review. No language or date restrictions were applied. All publications of clinical PK studies involving a group of pregnant women with a comparison to nonpregnant participants or nonpregnant population data were eligible to be included in this review. A total of 198 studies involving 121 different medications fulfilled the inclusion criteria. In these studies, commonly investigated drug classes included antiretrovirals (54 studies), antiepileptic drugs (27 studies), antibiotics (23 studies), antimalarial drugs (22 studies), and cardiovascular drugs (17 studies). Overall, pregnancy-associated changes in PK parameters were often observed as consistent findings among many studies, particularly enhanced drug elimination and decreased exposure to total drugs (bound and unbound to plasma proteins) at a given dose. However, associated alterations in clinical responses and outcomes, or lack thereof, remain largely unknown.

CONCLUSION

This systematic review of pregnancy-associated PK changes identifies a significant gap between the accumulating knowledge of PK changes in pregnant women and our understanding of their clinical impact for both mother and fetus. It is essential for clinicians to be aware of these unique pregnancy-related changes in PK, and to critically examine their clinical implications.

When one drug affects 2 patients: a review of medication for the management of nonlabor-related pain, sedation, infection, and hypertension in the hospitalized pregnant patient

One of the most difficult challenges health care providers encounter is drug selection for pregnant patients. Drug selection can be complex as efficacy and maternal side effects must be weighed against potential risk to the embryo or fetus. Verification of an individual drug's fetal safety is limited as most evidence is deduced from epidemiologic, prospective cohort, or case-control studies. Medication selection for the pregnant inpatient is a particularly complex task as the illnesses and conditions that require hospitalization mandate different medications, and the risk versus benefit ratio can vary significantly compared to the outpatient setting. Some degree of acute pain is not uncommon among inpatients. Acetaminophen is generally considered the drug of choice in pregnancy for mild to moderate acute pain, while most opioids are thought to be safe for short-term use to manage moderate to severe pain. Providing sedation is particularly challenging as the few options available for the general population are further limited by either known increased risk of congenital malformations or very limited human pregnancy data. Propofol is the only agent recommended for continuous sedation, which has a Food and Drug Administration classification as a pregnancy category B medication. Treatment of infections in hospitalized patients requires balancing the microbiology profile against the fetal risk. Older antimicrobials proven generally safe include beta-lactams, and those with proven fetal risks include tetracyclines. However, little to no information regarding gestational use is available on the newer antimicrobials that are frequently employed to treat resistant infections more commonly found in the inpatient setting. Management of maternal blood pressure is based on the severity of blood pressure elevations and not the hypertensive classification. Agents generally considered safe to use in hypertensive pregnant patients include methyldopa, labetolol, and hydralazine, while angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, hydrochlorothiazide, and atenolol should be avoided.

Antibiotic use in pregnancy

With a few notable exceptions, most antibiotics can be used with relative safety during pregnancy. Moreover, none of the antibiotics to date has been shown to be teratogenic, although tetracycline may cause yellow-brown discoloration of the deciduous teeth (a fetal effect). Thus, antibiotics should not be withheld from the pregnant woman, especially when indicated for serious, life-threatening infections.

Review of beta-lactam antibiotics in pregnancy. The need for adjustment of dosage schedules

beta-Lactam antibiotics represent the oldest class of antibiotics used in the treatment of infections, and benzylpenicillin (penicillin G) is still the most commonly used antibiotic agent during pregnancy. There is a number of studies to suggest that the pharmacokinetics of beta-lactam antibiotics are altered during pregnancy, indicating faster elimination of these antibiotics and lowered plasma concentrations. These changes are largely related to the physiological changes taking place in the maternal body. Generally, drugs are used cautiously during pregnancy, and dosages used may sometimes be inadequate. With regards to antibiotic agents, assurance of adequate therapy by applying pharmacokinetic knowledge when dosage schedules are designed should be a major concern so that the pregnancy is protected from the hazards of infection.

Pharmacokinetics of the acyclureidopenicillins piperacillin and mezlocillin in the postpartum patient

The postpartum patient experiences numerous physiologic alterations, which may affect the pharmacokinetics of certain drugs. Six patients received either piperacillin or mezlocillin intravenously immediately after delivery. Serum half-life and clearance were, respectively, 82.4 min and 202 +/- 105 ml/min for mezlocillin and 32.9 min and 456 +/- 88 ml/min for piperacillin. The data revealed that mezlocillin and piperacillin have significantly different pharmacokinetic reactions in the postpartum patient at the doses used.