Cardiac Drugs Used In Pregnancy

Digoxin

Digitalis plant leaves are the source of digoxin. Digoxin helps the heart beat more forcefully and consistently.

Mechanism of Action

This medicine works by preventing the body from producing a certain enzyme (known as sodium-potassium ATPase). The quantity of sodium and potassium that reaches the cells is managed by this enzyme. By inhibiting this enzyme, the heart's calcium and potassium levels rise. Systolic contraction force is increased, and the amount of oxygen used to produce a given amount of work is reduced.

Heart Rate Decreases

Conduction through the AV node and purkinje fibers is depressed.

Heart rate

Conduction through the AV node

Indications

• Left ventricular failure.
• Atrial fibrilation.
• Congestive Cardiac Failure.
• Supraventricular tachycardia.

Digoxin Side Effects

• Confusion, hallucinations, unusual thoughts or behavior.
• Blurred vision, yellowed vision.
• Bloody or black, tarry stools.
• Fast, slow or uneven heart rate.
• Nausea, diarrhea.
• Feeling weak or dizzy,.
• Headache, weakness, anxiety, depression,.
• Enlarged breasts in men,.
• Mild skin rash.,

Contraindications

• Ventricular Tachycardia,
• Hypercalcemia,
• Constrictive pericarditis and Myocarditis,
• High output state,
• Hypersensitivity,
• Hypokalemia.

Usual Dosage

• Adult: slow digitalization -average 0.25mg / day is given from the beginning. If no response after one week, increase the dose to 0.375mg and then 0.5mg after another week.
• Child: maintenance dose of . 5 - 15mcg /kg/day orally in 1 or 2 doses. 

Usual Adult Dose for Congestive Heart Failure

Rapid Digitalization with a Loading Dose:

Peak digoxin body stores of 8 to 12mcg / k * g generally provide a therapeutic effect with minimum risk of toxicity in most patients with heart failure and normal sinus rhythm. The loading dose should be administered in several fractions, with approximately half the total given as the first dose. Additional fractions of the total dose may be given at 6 to 8 hour intervals. Careful assessment of the patient's clinical response should be considered before each additional dose. If the patient's response necessitates a change from the calculated loading dose of digoxin, then calculation of the maintenance dose should be based upon the amount actually given.

Tablets:

Initial: 500 to 750 mcg usually produces a detectable effect in 0.5 to 2 hours with a maximal effect in 2 to 6 hours. Additional doses of 125 to 375 mcg may be given at 6 to 8 hour intervals until clinical evidence of an adequate effect is noted. The usual amount of digoxin tablets that a 70 kg patient requires to achieve 8 to 12 mcg/kg peak body stores is 750 to 1250 mcg.

Initial: 400 to 600 mcg of digoxin capsules generally produces a detectable effect in 0.5 to 2 hours with a maximal effect in 2 to 6 hours. Additional doses of 100 to 300 mcg may be given cautiously at 6 to 8 hour intervals until clinical evidence of an is noted. The usual amount of digoxin capsules that a 70 kg patient requires to achieve 8 to 12mcg / k * g peak body stores is 600 to 1000 mcg.

Injection:

Initial: 400 to 600 mcg of digoxin intravenously usually produces a detectable effect in 5 to 30 minutes with a maximal effect in 1 to 4 hours. Additional doses of 100 to 300 mcg may be given cautiously at 6 to 8 hour intervals until clinical evidence of an adequate effect is noted. The usual amount of digoxin injection that a 70 kg patient requires to achieve 8 to 12 mcg / k * g peak body stores is 600 to 1000 mcg. The injectable route is frequently used to achieve rapid digitalization, with conversion to digoxin tablets or digoxin capsules for maintenance therapy.

Maintenance Dose:

The doses of digoxin tablets used in controlled trials in patients with heart failure have ranged from 125 to 500mcg once daily. In these studies, the digoxin dose has been generally titrated according to the patient's age, lean body weight, and renal function. Therapy is generally initiated at a dose of 250 mcg once daily in patients under age 70 with good renal function. Calculated doses should be based on lean body weight. Premature:

Digitalizing (Loading) dose: Oral elixir: 20 to 30mcg / k g Intravenous: 15 to 25mcg / k g

Maintenance dose: 5 to 7.5mcg / k g Intravenous 4 to 6mcg / k g

Full Term:

• Digitalizing (Loading) dose: Oral elixir: 25 to 35mcg / kg Intravenous: 20 to 30mcg / k g Maintenance dose: Oral 6 to 10 mcg/kg: Intravenous 5 to 8mcg / k g 1 - 24months :
• Digitalizing (Loading) dose: Oral elixir: 35 to 60mcg / kg Intravenous: 30 to 50mcg / k g
• Maintenance dose: Oral 10 to 15mcg / k * g Intravenous 7.5 to 12mcg / k g

3 to 5 years:

• Digitalizing (Loading) dose: Oral elixir: 30 to 40mcg / k g Intravenous: 25 to 35mcg / k g
• Maintenance dose: Oral 7.5 to 10mcg / k g Intravenous 6 to 9mcg / k g

6 to 10 years:

• Digitalizing (Loading) dose: Oral elixir: 20 to 35mcg / k g Intravenous: 15 to 30mcg / k g
• Maintenance dose: Oral 5 to 10mcg / k g Intravenous 4 to 8mcg / k g

11 years and older:

• Digitalizing (Loading) dose: Oral elixir: 10 to 15mcg / k g Intravenous: 8 to 12mcg / k g
• Maintenance dose: Oral 2.5 to 5mcg / k g Intravenous 2 to 3mcg / k g
  • Because overdoses are so frequent, make sure to utilize the appropriate patient, dose, route, timing, medication, and documentation.
  • Before each dosage, take your pulse for a full minute and record the rate, rhythm, and quality. Refrain from taking the medication and let the doctor know if the reading is below 60 or irregular.
  • Digoxin enhances renal output, thus keep intake and output constant for the first several days. Make sure the patient is aware of the overdose symptoms before releasing them.
  • Avoid giving calcium quickly by I/V to patients receiving digoxin. Digoxin-like effects on cardiac excitability and contractibility are shared by calcium, which can cause serious arrhythmia.

Digoxin Pregnancy Warnings

There have been no reports linking digoxin to congenital abnormalities. As the pregnancy progresses, the fetal concentration of digoxin increases across the placenta. The reported concentrations of maternal serum in the umbilical cord were 50%, 81%, and 83%. In the first half of human gestation, the fetal heart has only a modest capacity to bind digoxin; however, in the second half, it concentrates digoxin. The tolerance of fetuses and newborns is higher (2 to 4 ng/m*L) than that of adults (less than 2 ng/m*L). It is advised to monitor maternal plasma clearance of digoxin both antepartum and postpartum because pregnancy significantly increases this clearance.

Digoxin has been effectively used throughout gestation to treat maternal congestive heart failure, arrhythmias, and fetal arrhythmias without any reports of fetal injury; nevertheless, digoxin should only be administered during pregnancy when benefit exceeds risk.

Low Molecular Weight Heparin

Low-molecular-weight heparin (LMWH) is a category of anticoagulant drugs in medicine. They are utilized in the management of myocardial infarction as well as the prevention and treatment of venous thromboembolism (deep vein thrombosis and pulmonary embolism).

Mechanism of Action

Heparin is a naturally occurring polysaccharide that prevents thrombosis by inhibiting the coagulation process. The molecular weights, or lengths, of natural heparin's molecules vary. By preventing thrombin from functioning, it causes anticoagulation.

It works against thrombin, prothrombin, and thromboplastin.

Indications

• Venous thromboembolism Deep vein thrombosis Pulmonary embolism Myocardial Infraction Patients with cancer are at higher risk of venous thromboembolism and LMWHs are used to reduce this End-stage renal disease risk.

Contraindications

• The use of LMWHs should be avoided in patients with known allergies to LMWHs, heparin, sulfites or benzyl alcohol.
• Thrombocytopenia.
• Hypersensitivity.
• In patients with active major bleeding.

Patients having a history of heparin-induced thrombocytopenia (also known as heparin-induced low blood platelet count) (HIT). In cases of severe bleeding, such as brain or gastrointestinal hemorrhage, high therapeutic dosages are contraindicated. Other than switching to unfractionated heparin, it could be able to lower the dose.

Precautions

LMWHs should be used with extreme caution in patients undergoing any procedure involving spinal anaesthesia/puncture, in conditions with increased risk of bleeding or in patients with a history of heparin- induced thrombocytopenia.

Side Effects

• Bleeding is the most frequent adverse effect, which can be serious or even deadly.
• Allergic responses
• responses at the injection site
• liver enzyme test increases, frequently without symptoms.
• Heparin-induced thrombocytopenia is a complication that can occasionally make using heparin and LMWHs more challenging.

Safety of Low-Molecular-Weight Heparin in Pregnancy

During pregnancy, unfractionated heparin (UFH) is still the preferred anticoagulant. Due to logistical benefits and an association with a lower incidence of osteoporosis and HIT, low-molecular-weight heparins (LMWH) are a desirable substitute for UFH. Unfractionated heparin appears to be riskier than LMWH when used as an anticoagulant during pregnancy.

Antidote

Protamine is used to bind to heparin in clinical settings where the antithrombotic effect of LMWHs needs to be countered.

Nursing Considerations

• Before administering a drug, be sure the blood clotting test has been completed.
• To reduce tissue stress during injection, use a tiny needle.
• Before giving a deep subcutaneous injection, tell the patient to sit or lie down.
• To avoid bruising, avoid rubbing the injection site. With each injection, switch up the administrative location.
• Examine the fetal hert rate.
• Examine the PV for bleeding.
• Special precaution should be taken in APH cases
• Watch for sign of bleeding and notify doctor if seen any.
• Because it can be given subcutaneously and does not require APTT monitoring. The use of LMWH needs to be monitored closely in patients at extremes of weight or in-patients with renal dysfunction.