RTS in Pregnancy - University of Strathclyde Science

MP223 PHARMACY ISSUES IN PREGNANCY NORMAL FUNCTION OF THE NERVOUS & ENDOCRINE SYSTEMS  Learning outcomes To understand the nature of common ailments which occur during pregnancy To learn how to respond to symptoms related to pregnancy in Community Pharmacy. Know what is teratogenic...

MP223 PHARMACY ISSUES IN PREGNANCY NORMAL FUNCTION OF THE NERVOUS & ENDOCRINE SYSTEMS  Learning outcomes To understand the nature of common ailments which occur during pregnancy To learn how to respond to symptoms related to pregnancy in Community Pharmacy. Know what is teratogenicity - which common medicines and drugs affect foetal development and how.  Conception The start of pregnancy is usually calculated from the 1st day of the last menstrual period= ‘menstrual age’ (usually about 2 weeks ahead of when conception actually occurs). Conception date might be the day sex occurred or some days later as sperm can live in the body for up to 5 days. Foetal Development Foetal Development Foetal Development Foetal Development  Foetal development 3 distinct stages Blastocyst formation (0-16 days) after conception Organogenesis (17-60 days)- cell division, migration, differentiation and cell death. Histogenesis & functional maturation (61 days until full term) Average pregnancy is 280 days/40 weeks but can get survival at 22 weeks (foetal viability)  Trimesters of pregnancy 3 trimesters: 13/14 weeks each  maternal weight (11-14kg)  Blood volume, uterine and breast size (1st T)  Deposition of fat stores (2nd T)  Foetal and placental growth (3rd T) Physiological changes occur in different systems e.g CV :  HR, BP GI:  Gastric acid secretion, gastric emptying Renal: bladder capacity and urinary control Some women unaware of being pregnant- accidental exposure to drugs/chemicals etc  Route of Transfer Placenta Respiratory function (gas exchange) Excretory function (maintains water and pH balance) Resorptive function (like GI tract) Placenta can act as a barrier BUT lipid soluble drugs, particularly low Mwt (and lipophilic/non ionised) - can pass through. Transfer across placenta determined by concentration gradient between foetal & maternal circulation- passive diffusion of free non ionised molecules  Placental transfer Quantity of drug reaching foetus depends on physio-chemical characteristics of the molecule and maternal pharmacokinetic parameters which vary according to the term of pregnancy Classified into 3 groups depending on degree of placental transfer: High: drug crosses rapidly, at equilibrium foetal conc close to maternal pharmacological concentration Limited: foetal concentration is lower than maternal concentration Excess: Foetal concentration is higher than maternal (limited retro-passage to maternal circulation) Some compounds don’t cross at all e.g pituitary hormones, insulin, TSH  Prescribing in Pregnancy Potential for harm to foetus or mother- so need to weigh up the risk/harm benefit. Drug therapy in pregnancy arises from pre- existing medical conditions or due to pregnancy related complications e.g diabetes, pre-eclampsia or venous thromboembolsim (VTE) Need to treat foetus? What is risk to mother? Chosen therapy should be ‘least harmful’, lowest possible dose, dosage intervals/frequency etc.  Factors to consider when prescribing in pregnancy Maternal factors Foetal factors Drug factors 1. Implications of not taking 1. Risk of congenital 1. Altered absorption, the drug malformations (esp weeks distribution, metabolism 2. Maternal choice 1-8) and excretion. 3. Gestation 2. Risk of organ toxicity 2. Narrow therapeutic index 4. Co-morbidities 3. Withdrawal postpartum 3. Safer alternative 4. Ability to cross placenta 5. Topical Vs systemic 6. Adverse effects Common ailments seen in Community pharmacy [RTS In Pregnancy]. Nausea and vomiting Indigestion / Haemorrhoids (morning acid reflux sickness) Infections UTIs / Thrush Anaemia (antibiotics)  Morning sickness Nausea & Vomiting in 70-80% of all pregnant women 4-8 weeks gestation- rarely after 16 weeks Severe form: hyperemesis gravidarum (nausea that does not ‘go away’, weight loss, reduced appetite, dehydration, and feeling faint- risk of starvation and dehydration) Hormonal, neurological, physical factors (hCG hormone, decreased gastric emptying) Treatment is by anti-emetics: usually POMs so should refer to GP. Hill et al. Management of severe N&V in pregnant women. Pharm J. 1st Jan 2013.  Constipation & Haemorrhoids Constipation: 10-30% pregnancies,  motility of smooth muscle caused by in progesterone. Food passes through the GIT more slowly. Also  activity, may be taking iron supplements, consider growth of the baby - Laxatives (bulk forming, avoid stimulant laxative esp in later stages) Haemorrhoids: Enlarging uterus exerts pressure,  blood volume leading to venous dilation and engorgement. Itching, protrusion of mass, pain , bleeding -(haemorrhoid / anaesthetic cream/ointments)  Indigestion >25& of pregnancies- usually 3rd Trimester Belching, nausea and a bloated feeling. Reflux of stomach acid- worse on eating, lying or bending over. Physical measures e.g small frequent meals, elevation on top of bed, avoid certain foods Use Antacids with or without an alginate e.g Gaviscon Advance or CaCO3. Use Al or Mg containing antacids on an ‘as required’ basis.  Thrush Thrush is a fungal infection caused by candida albicans An opportunistic infection- caused by hormonal changes during pregnancy as the vaginal environment is altered Can use topical agents (other formulations not for OTC sale) e.g clotrimazole (canesten cream) BUT best to refer to GP – likely to prescribe oral treatment Natural yoghurt contains probiotic called acidophilus- may insert into vagina  Urinary Tract Infection UTIs are very common during pregnancy. (growing foetus can put pressure on the bladder and urinary tract. This traps bacteria or causes urine to leak). Do not treat OTC – refer to GP, probably GP10 Rx for an antibiotic  Anaemia Iron deficiency can cause anaemia during infancy, spontaneous abortion, premature delivery, low birth weight infant. Iron supplements- variety of doses, usually 200mg FeSO4 or other iron salts –depending on tolerability. Also consider diet- leafy veg, cereals.  Common conditions experienced during pregnancy Hypertension and pre-eclampsia Gestational diabetes Venous thromboembolism (VTE) Obstetric cholestasis Not for management in Community Pharmacy- although will be seen in Primary Care / GP.  Teratogenicity Teratogen: a substance, organism or process that causes malformations in a foetus (congenital abnormalities) Unethical to conduct RCTs- mainly from epidemiological studies, anecdotal evidence/experience Relatively small number of drugs implicated- prescribed/illicit/legal drugs Infections / viruses Genes Environmental e.g lead  Teratogenicity Effects correspond to stages of foetal development- (most influence on organogenesis stage) Physical effects (structural abnormalities, dysfunctional growth-e.g 1st 6 weeks Heart & CNS- congenital heart defects or neural tube defects) Behavioural effects- i.e effects on brain which manifest as behaviour – avoid psychotropic drugs. check individual monograph in the BNF or the drug’s SPC http://www.uktis.org/ - UK teratology information service  Major teratogenic drugs in humans Organ formation occurs in the first 3 Alcohol months of Anticoagulants Warfarin pregnancy, teratogenic drugs Antidepressants Lithium taken in this period Anticonvulsants Valproic acid therefore tend to Carbamazepine cause structural Chemotherapy 6-mercaptopurine Methotrexate defects. Cyclophosphamide From 3 months Hormones Androgens onwards, 19-Norsteroids teratogenic drugs Retinoids Isotretinoin Acitretin tend to cause Thalidomide growth defects. FDA – previously had 5 Categories: A, B, C, D or X BUT these left patients and providers ill-informed and resulted in false assumptions about the actual meaning of the letters. A - drug is well-studied and poses no threat to a developing baby B – drug less-studied, but probably still low-risk C is a drug that has not been studied and therefore the risk is unknown D-based on animal or human data, may pose a risk  Breast Feeding Insufficient evidence – advisable to administer only essential drugs to a mother during breast feeding Use drugs with short half life Feed just before mother takes medication (trough level) Lipid soluble drugs diffuse into breast milk : concentrate because of high fat content of milk. Generally, the quantity/conc of drug is too small to be of concern Briggs & Freeman – Drugs in Pregnancy and Lactation: A reference Guide to Fetal and Neonatal risk (treatment options & risk assessment)  Ethical choice To medicate or not to medicate? Risk benefit ratio? Which medicine is safest? Consider your own prejudices- alcohol, cocaine, cigarette smoking.