Anticonvulsants, anticoagulants

This topic contains anticonvulsants used in obstetrics such as magnasium sulphate, diazepam, phenytoin and anticoagulants such as heparin and warfarin.

1. ANTICONVULSANTS USED IN OBSTETRICS BY, MS. PRIYANKA GOHIL MSc (N) OBG, PhD SCHOLAR MBNC,UTU

2. INTRODUCTION Convulsion in pregnancy is largely due to eclampsia. Other causes are epilepsy, meningitis, cerebral maleria and cerebral rumors. Eclampsia should be considered first unless proved otherwise by history, examination and investigation.

3. MAGNASIUM SULPHATE MODE OF ACTION: It decreases the acetylcholine release from the nerve endings and reduces the motor end plate sensitivity to acetylcholine. It also blocks the calcium channels. It causes vasodilation, increases cerebral, uterine and renal blood flow. It decreases intracranial edema.

4. DOSE IM: Loading dose- 4 g IV (20% solution) over 3-4 min. To follow 10 g (50% solution) deep IM on alternate buttock every 4 hours. IV: Loading dose: 4-6 g over 15-20 min, Maintenance dose is 1-2 g/hr infusion. Repeat injections are given only if knee jerks are present, urine output >30 ML/hr and respiration rate > 12/min. Therapeutic levels of serum mg is 4-7 mEq/L.

5. SIDE EFFECTS MgSO 4 is relatively safe and is the drug of choice. Muscular paresis (diminished knee jerks) respiratory faillure. Renal function is to be monitored. It does not affect the duration of labour. Antidote: injection calcium gluconate 10% 10 ML IV Fetal effects are usually absent. It is contraindicated in patients with myasthenia gravis.

6. DIAZEPAM MODE OF ACTION: Central muscle relaxant and anticonvulsant. DOSE : Initially 20-40 mg IV to be followed by an infusion containing 500 ML of dextrose with 40 mg of diazepam, the drip rate being 30 drops/min or adjusted as per need Status epilepsticus: 10-20 mg IV after 1 hour, may be followed by IV infusion to a maximum of 3 mg/kg over 24 hours

7. SIDE EFFECTS Mother: Hypotension Fetus: Respiratory depressant effect which may last for even three weeks after delivery Hypotonia, thermoregulatory problem in newborn.

8. PHENYTOIN MODE OF ACTION: Centrally acting anticonvulsant DOSE : Eclampsia: 10 mg/kg IV- at the rate not more than 50 mg/min followed 2 hours later by 5 mg/kg Epilepsy: 300-400 mg daily orally in devided doses. Status epilepticus: 18 mg/kg slow IV (50 mg/min), maintenance dose of about 100 mg is given at an interval of 6-8 hours. BP and ECG monitoring should be done.

9. SIDE EFFECTS Maternal: Hypotension, cardiac arrythmias and phlebitis at the injection site. Fetal hydantoin syndrome (characteristic pattern of mental and physical birth defects that results from maternal use of the anti-seizure drug) when used in first trimester is observed in 5-10 % offspring. This may be due to the disease itself with a genetic predisposition or due to drug metabolism and deficient folate level.

10. ANTICOAGULANTS

11. INTRODUCTION Anticoagulants are not commonly used in pregnancy. Cardiac disease, venous thrombosis, antiphospholipid syndrome (disorder in which the immune system mistakenly attacks normal proteins in the blood) are some of the indications.

12. HEPARIN Also known as unfractionated heparin Low molecular weight heparin MODE OF ACTION Inibits action of thrombin. It also enhances the activity of antithrombin III.

13. DOSE 5000-10,000 IU to be administered parenterally. Deep vein thrombosis and pulmonary embolism: loading dose is 5000 units IV followed by continuous infusion of 18 units/kg/hour Pregnancy: 5000-10,000 SC every 12 hours Deltaparin sodium (Fragmin): 2500 units SC evry 24 hours

14. SIDE EFFECTS Maternal: Hemorrhage, urticaria with long-term use thrombocytopenia, hypokalemia. Fetal: It does not cross the placenta Low molecular weigth heparins- as effective and safe as unfractionated heparin. Longer half life and once daily dose is cinvenient. Standard dose does not require monitoring.

15. WARFARIN MODE OF ACTION Interfers with synthesis of vitamin K dependent factors (II, VII, IX, X) DOSE: 10 mg orally for initial 2 days then 3-9 mg daily ( taken at the same time each day) depending upon the prothrombin time.

16. SIDE EFFECTS Maternal: Hemorrhage Fetal: Cornadi's syndrome( skeletal and facial abnormalities), optic atrophy, microcephaly, chondrodysplasia punctata (skeletal displasia).

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