Oxytocics (Uterotonics)

Oxytocin

• Dose:
  
  • Induction/Augmentation: 5–10 IU IM or IV infusion (start 1–2 mU/min, increase by 1–2 mU every 15–30 min).
  • PPH Prevention: 10 IU IM after delivery of anterior shoulder.
  • PPH Treatment: 20–40 IU in 500–1000 mL IV fluid at 125–250 mL/hr.
• Class: Synthetic posterior pituitary hormone.
• Mechanism of Action: Stimulates uterine smooth muscle contraction by increasing intracellular calcium; mimics natural oxytocin.
• Indications:
  
  1. Labor induction (post-term, PROM, diabetes, preeclampsia).
  2. Labor augmentation (dystocia).
  3. Active management of third stage (AMTSL).
  4. Postpartum hemorrhage control.
  5. Lactation support (rare).
• Contraindications:
  
  1. Hypersensitivity to oxytocin.
  2. Cephalopelvic disproportion.
  3. Previous classical cesarean or major uterine surgery.
  4. Fetal distress.
  5. Grand multiparity (>5).
  6. Placenta previa.
• Nursing Considerations:
  
  • Continuous CTG monitoring for hyperstimulation (contractions >5 in 10 min).
  • Titrate infusion carefully; stop if tachysystole.
  • Monitor fluid balance (risk of water intoxication).
  • Keep Syntometrine/misoprostol ready for refractory PPH.
  • Store at 2–8°C; protect from light.
• Adverse Effects: Uterine hyperstimulation, fetal distress, hyponatremia, hypotension, nausea.

Misoprostol

• Dose:
  
  • PPH Prevention: 600 mcg oral/sublingual/rectal post-delivery.
  • PPH Treatment: 800–1000 mcg rectal.
  • Induction (off-label): 25 mcg vaginal every 4–6 hrs.
• Class: Synthetic prostaglandin E1 analogue.
• Mechanism of Action: Causes cervical ripening and uterine contractions via prostaglandin receptors.
• Indications:
  
  1. PPH prevention/treatment (where oxytocin unavailable).
  2. Induction of labor (unfavorable cervix).
  3. Medical abortion (with mifepristone).
  4. Incomplete abortion management.
• Contraindications:
  
  1. Known allergy to prostaglandins.
  2. Active asthma (bronchoconstriction risk).
  3. Unstable hemodynamics.
  4. Suspected uterine rupture.
• Nursing Considerations:
  
  • Monitor temperature (pyrexia common).
  • Observe for shivering, diarrhea, vomiting.
  • Use gloves for rectal administration.
  • Avoid in scarred uterus for induction (rupture risk).
  • Stable at room temperature.
• Adverse Effects: Hyperpyrexia, shivering, diarrhea, nausea, uterine hypertonus.

Ergometrine (Methylergometrine)

• Dose: 0.2 mg IM/IV (repeat every 2–4 hrs, max 5 doses).
• Class: Ergot alkaloid.
• Mechanism of Action: Causes sustained uterine contraction via serotonin and alpha-adrenergic receptors.
• Indications:
  
  1. PPH prevention (with oxytocin in AMTSL).
  2. PPH treatment (second-line).
• Contraindications:
  
  1. Hypertension, preeclampsia/eclampsia.
  2. Cardiac disease.
  3. Peripheral vascular disease.
  4. First/second stage of labor.
• Nursing Considerations:
  
  • Monitor BP (vasoconstriction).
  • Avoid IV push (risk of hypertensive crisis); give slowly.
  • Refrigerate (2–8°C).
• Adverse Effects: Hypertension, nausea, vomiting, headache.

Antihypertensives

Methyldopa

• Dose: 250–500 mg oral 6–8 hourly (max 3 g/day).
• Class: Centrally acting alpha-2 agonist.
• Mechanism of Action: Reduces sympathetic outflow, lowering BP.
• Indications:
  
  1. Chronic hypertension in pregnancy.
  2. Gestational hypertension.
  3. Preeclampsia (mild).
• Contraindications:
  
  1. Active liver disease.
  2. Depression.
  3. Pheochromocytoma.
• Nursing Considerations:
  
  • Monitor BP, pulse, urine output.
  • Check LFTs baseline and periodically.
  • Warn about drowsiness.
• Adverse Effects: Sedation, depression, dry mouth, Coombs-positive hemolytic anemia.

Nifedipine

• Dose:
  
  • Immediate-release: 10–20 mg oral/stat, repeat after 30 min if needed.
  • Sustained-release: 30–60 mg daily.
• Class: Calcium channel blocker (dihydropyridine).
• Mechanism of Action: Inhibits calcium influx in vascular smooth muscle → vasodilation.
• Indications:
  
  1. Severe hypertension/preeclampsia.
  2. Preterm labor tocolysis (off-label).
• Contraindications:
  
  1. Cardiogenic shock.
  2. Immediate-release with beta-blockers (hypotension risk).
• Nursing Considerations:
  
  • Bite and swallow immediate-release for sublingual effect.
  • Monitor for reflex tachycardia.
  • Avoid grapefruit juice.
• Adverse Effects: Headache, flushing, tachycardia, edema.

Hydralazine

• Dose: 5–10 mg IV every 20–30 min (max 20 mg).
• Class: Direct arterial vasodilator.
• Mechanism of Action: Relaxes arteriolar smooth muscle.
• Indications:
  
  1. Acute severe hypertension in pregnancy.
  2. Eclampsia (with MgSO4).
• Contraindications:
  
  1. Coronary artery disease.
  2. Mitral valve rheumatic heart disease.
• Nursing Considerations:
  
  • Give undiluted slow IV push.
  • Monitor for lupus-like syndrome (long-term).
• Adverse Effects: Headache, tachycardia, palpitations.

Labetalol

• Dose:
  
  • Oral: 100–400 mg 12 hourly.
  • IV: 20 mg bolus, double every 10 min (max 300 mg).
• Class: Alpha + beta blocker.
• Mechanism of Action: Blocks adrenergic receptors → reduces BP and HR.
• Indications:
  
  1. Severe preeclampsia/eclampsia.
  2. Chronic hypertension.
• Contraindications:
  
  1. Asthma/COPD.
  2. Bradycardia, heart block.
• Nursing Considerations:
  
  • Monitor FHR (beta-blockade).
  • IV compatible with normal saline.
• Adverse Effects: Fatigue, bronchospasm, fetal bradycardia.

Anticonvulsants

Magnesium Sulfate

• Dose:
  
  • Loading: 4 g IV over 20 min.
  • Maintenance: 1 g/hr IV for 24 hrs.
  • IM (Zuspan/Pritchard): 5 g IM each buttock, then 5 g every 4 hrs.
• Class: Physiological calcium antagonist.
• Mechanism of Action: Prevents seizures by NMDA receptor blockade and vasodilation.
• Indications:
  
  1. Eclampsia prevention/treatment.
  2. Severe preeclampsia.
  3. Preterm labor tocolysis (limited).
• Contraindications:
  
  1. Myasthenia gravis.
  2. Heart block.
  3. Renal failure (adjust dose).
• Nursing Considerations:
  
  • Monitor patellar reflex, RR (>12/min), urine output (>30 mL/hr).
  • Keep calcium gluconate 1 g IV for toxicity.
  • Serum Mg level: therapeutic 4.8–8.4 mg/dL.
• Adverse Effects: Flushing, muscle weakness, respiratory depression, pulmonary edema.

Analgesics

Pethidine (Meperidine)

• Dose: 50–100 mg IM every 2–4 hrs (max 400 mg/day).
• Class: Opioid agonist.
• Mechanism of Action: Binds mu receptors → analgesia, sedation.
• Indications:
  
  1. Labor pain.
  2. Post-cesarean pain.
• Contraindications:
  
  1. MAOI use.
  2. Respiratory depression.
• Nursing Considerations:
  
  • Monitor neonatal respiration if given near delivery.
  • Antidote: Naloxone.
• Adverse Effects: Nausea, drowsiness, neonatal depression.

Paracetamol

• Dose: 500 mg–1 g oral/IV 4–6 hourly (max 4 g/day).
• Class: Non-opioid analgesic/antipyretic.
• Mechanism of Action: COX inhibition in CNS.
• Indications:
  
  1. Mild labor/postpartum pain.
  2. Fever.
• Contraindications: Severe liver disease.
• Adverse Effects: Rare; hepatotoxicity in overdose.

Antibiotics

Benzylpenicillin

• Dose: 2–5 MU IV/IM 6 hourly.
• Class: Beta-lactam.
• Indications:
  
  1. GBS prophylaxis.
  2. Syphilis.
  3. Puerperal sepsis.
• Adverse Effects: Allergy, Jarisch-Herxheimer reaction.

Ceftriaxone

• Dose: 1–2 g IV/IM daily.
• Class: 3rd-generation cephalosporin.
• Indications:
  
  1. Puerperal sepsis.
  2. Chorioamnionitis.
• Adverse Effects: Rash, diarrhea.

Metronidazole

• Dose: 400–500 mg oral/IV 8 hourly; 1 g rectal PRN.
• Class: Nitroimidazole.
• Indications:
  
  1. Bacterial vaginosis.
  2. Trichomoniasis.
  3. Anaerobic infections.
• Contraindications: 1st trimester (avoid).
• Adverse Effects: Metallic taste, disulfiram reaction.

Antiemetics

Promethazine

• Dose: 12.5–25 mg IM/IV/oral 4–6 hourly.
• Class: Phenothiazine.
• Indications:
  
  1. Hyperemesis gravidarum.
  2. Postoperative nausea.
• Adverse Effects: Sedation, dry mouth.

Tocolytics

Nifedipine (off-label)

• Dose: 10–20 mg oral every 15 min (max 40 mg in 1 hr), then 10–20 mg 4–6 hourly.
• Indications: Preterm labor (<34 weeks).
• Adverse Effects: Hypotension, headache.

Others

Ferrous Sulfate + Folic Acid

• Dose: 200 mg + 0.4 mg daily.
• Indications: Anemia prevention/treatment.

Vitamin K (Phytomenadione)

• Dose: 1 mg IM to newborn.
• Indications: Prevent HDN.

Tetanus Toxoid

• Dose: 0.5 mL IM (2 doses in pregnancy).
• Indications: Maternal/neonatal tetanus prevention.

Rho(D) Immune Globulin

• Dose: 300 mcg IM at 28 weeks and within 72 hrs postpartum (if Rh-negative).
• Indications: Prevent Rh isoimmunization.