Digoxin- Intro, PK, Actions, Adverse effects, Uses.
Digoxin is a Cardiac glycoside obtained from the plant Digitalis lanata. It is an inotropic agent, which increases cardiac contractility and output without concurrently increasing HR
PK: Half life= 40 hrs PPB= 25% Therapeutic dose= 0.5-1.4 ng/ml Toxic dose= >2ng/ml Therapeutic index= 1.5-2 Route of adm= oral or iv ,Route of elimin= Renal
Actions:
1. Cardiac: increases force of contraction, decreases HR by direct, vagomimetic and antiadrenergic action.
Decreases APD, increases ERP. Decreases conduction velocity through AVN. ECG changes include T-wave flat/inversion, PR prolongation, QT shortening, ST segment depression.
2. Kidney: Diuresis d/t improved perfusion
3. CNS: Stimulation of CTZ at high doses— nausea,vomiting. Higher doses produce CNS disturbances.
Adverse effects:
- Cardiac: Any type of arrythmia (m/c= bigeminy), AV block and bradycardia
- Extracardiac: GI upset, CNS disturbances, Skin rashes and gynaecomastia
Uses:
- A.fib and AFl - maintain Vent rate
- CHF (with low EF)
- PSVT- when accompanied by CHF
Outline management of unstable angina.
Unstable angina is an Acute Coronary Syndrome (ACS), occuring due to rupture of an atherosclerotic plaque, causing thrombosis and progressive occlusion of coronary artery.
-It requires aggressive therapy with combination of drugs to prevent further occlusion, to improve myocardial perfusion and decreasing myocardial stress.
- Antiplatelet drugs: Low Dose Aspirin, Clopidogrel, Prasugrel are used. GPIIB/IIIA receptor antagonists (eg Abciximab) be useful in severe ACS
- Anticoagulants- LMWH, Unfractioned heparin
- Nitrates - Sublingual GTN given first. If no relief occurs after 3 tablets at 5 min intervals, IV infusion is started. BP should be monitored during iv
- Beta blockers- (Metoprolol/Atenolol) Routinely given in unstable Angina unless contraindicated.
- Statins - Improve outcome in UA
Antihypertensives save in pregnancy.
Better Mother Care During Hypertension
Beta blockers (labetalol) Methyldopa (DOC) Clonidine, CCB DHP (discontinued before labor) Hydralazine
Neprilysin inhibitor: Name of drug, MOA, Uses, side effects.
Sacubitril is a Neprilysin or NEP inhibitor.
MOA: inhubits degradation of natriuretic pepides ANP, BNP and other vasodilator peptides like Bradykinin, substance P etc —> natriuretic, diuretic and vasodilator effect, decrease in Ang 2 and aldosterone —> decreased preload, afterload, circulating volume —> improved Left ventricular function
Use: Along with ARB Valsartan for Class 2 and class 4 Congestuve heart failure.
Side effects: Hypotension, Hypokalemia, Angioedema.
