Drugs in pregnancy. Pharmacokinetics in pregnancy.

Pharmacokinetics describes the handling of a drug by the body - how the drug is absorbed, distributed and eliminated and how these processes determine plasma concentrations of the drug. Changes in maternal physiology during pregnancy influence pharmacokinetics, and this may have important sequelae for drug dosing, especially for drugs for which adverse effects occur at concentrations within, or just above, the therapeutic range. For many drugs absorption is decreased and elimination increased, thus tending to reduce plasma concentrations. There are, however, relatively few specific data on pharmacokinetics in pregnancy, compared to the non-gravid state, because of the obvious ethical issues surrounding studies during pregnancy. Most therapeutic guidelines are thus based on observational studies and basic principles.     

Prescribing in pregnancy. Epilepsy in pregnancy

In women with epilepsy, seizure control during pregnancy can be improved by maintaining the serum anticonvulsant drug concentration within the therapeutic range. Treatment with one anticonvulsant drug plus folic acid supplementation 5 mg per day seems appropriate in most cases. This should be achieved before conception whenever possible. No anticonvulsant drug seems free of teratogenic risk. With the commonly used anticonvulsant drugs-phenytoin, phenobarbitone, carbamazepine and sodium valproate-the risk is relatively low and represents less potential harm to the fetus than might occur with uncontrolled seizures.     

Ectopic pregnancy.

The diagnosis and management of ectopic pregnancy is changing rapidly. More sensitive pregnancy tests and high-resolution transvaginal sonography are making the diagnosis of ectopic pregnancy easier and earlier. In the future, we may become more confident with the ultrasound diagnosis of some ectopic pregnancies such that laparoscopic confirmation will not be required. These patients may be treated with systemic methotrexate. However, at the present time laparoscopy is essential for diagnostic confirmation of most ectopic pregnancies. It is senseless for a skilled laparoscopist to perform a diagnostic laparoscopy, remove the laparoscope, and then proceed with laparotomy or some nonsurgical treatment. There is sufficient evidence in the literature to demonstrate that laparoscopic management of ectopic pregnancies is equally safe, equally effective, and less traumatic than laparotomy. It should replace laparotomy as treatment for most ectopic pregnancies. Unfortunately, there are not enough trained laparoscopists to manage the 88,000 ectopic pregnancies per year in the United States. Operative laparoscopy deserves more emphasis in postgraduate and residency training programs.     

Ectopic pregnancy.

During the last two decades, the incidence of ectopic pregnancy was shown to be rising. At the same time, ectopic pregnancy became less lethal due to improvements in diagnostic procedures, which are now able to confirm the ectopic implantation before the occurrence of life-threatening hemorrhagic complications. Earlier diagnosis has also offered the possibility of conservative surgical and medical treatments.     

Prescribing in pregnancy. Bacterial infections in pregnancy

Certain infections, such as UTI, may have an increased incidence during pregnancy owing to physiological changes. Between 2 and 10% of pregnant women have covert or asymptomatic bacteriuria which is associated with an increased incidence of acute symptomatic UTI in later pregnancy if left untreated. Thus antenatal screening to detect the presence of bacteriuria is justified. Most women will remain abacteriuric throughout the remainder of pregnancy after a single course of antibiotic therapy but a small percentage will fail to respond or have recurrent UTIs. Maternal infection with certain organisms, namely those which resist phagocytosis, may result in transplacental infection of the fetus in utero. Congenital syphilis is preventable and antenatal serological screening is usually routinely performed. Listeriosis following maternal infection in pregnancy is less predictable and the epidemiology of L. monocytogenes remains unclear. Genital tract carriage of sexually transmitted organisms, such as N. gonorrhoeae or C. trachomatis, may also be detected during pregnancy and antibiotic therapy will be indicated to eradicate such organisms and prevent maternal and neonatal morbidity. Antibiotic therapy during pregnancy will not, however, eradicate carriage of GBS from the genital tract, although carriage status at term can now be reliably predicted by using enriched culture techniques and swabbing multiple sites on more than one occasion. Where carriage is confirmed, the administration of intrapartum antibiotics to the mother appears a useful approach in the prevention of early onset neonatal GBS disease. Broad spectrum intrapartum antibiotics may also be indicated when there are complications, such as prolonged labour or premature rupture of membranes, which are associated with a higher incidence of maternal postpartum endometritis and morbidity than in women following uncomplicated vaginal delivery. Serious postnatal sepsis and shock is fortunately now rare. The pharmacokinetics of antibiotics in late pregnancy and the puerperium are altered and maternal serum levels may be reduced by 10-50%. Most antibiotics cross the placenta and are excreted in breast milk. Some agents, such as the beta-lactams, are considered safe in pregnancy and breast-feeding women while other antibiotics are contraindicated owing to risk of toxicity (often rare) or teratogenicity (often theoretical). Caution is necessary with many agents which may cause side effects or toxicity although this does not necessarily contraindicate their use in pregnancy.(ABSTRACT TRUNCATED AT 400 WORDS)     

Scleroderma in pregnancy.

The case records of four patients with scleroderma who booked for care between 1989 and 1994 at the Birmingham Women's Hospital (formerly the Birmingham Maternity Hospital), a tertiary care obstetric unit, were studied retrospectively. The aim of the study was to look at infertility, early and late pregnancy losses, fetal growth retardation and maternal complications in these four women afflicted with this rare condition. Two patients gave a history of infertility. There were two growth retarded fetuses and one intrauterine fetal death. Worsening Raynaud's phenomenon occurred in three patients. Another patient developed massive haematemesis due to an oesophageal tear resulting from intractable vomiting. Scleroderma may adversely affect pregnancy: obstetrical complications are common and require close monitoring.     

Cancer and pregnancy.

The diagnosis of cancer rarely complicates pregnancy. Despite the fact that advanced disease is often encountered, there is no scientific evidence that the pregnant state alters the neoplastic process. Only through careful attention to the patient can the clinician detect cancer at an early stage and offer the patient reasonable hope for a cure.     

Parasuicide in pregnancy.

Parasuicide is a significant risk factor for completed suicide. Furthermore, suicide is emerging as an important cause of maternal death, especially among young mothers. There are no published reports of parasuicide in pregnancy from poor countries. Three cases are reported to highlight this issue and to demonstrate management options available to health professionals working in the field of women's health.