pharmacology revised

Cardiac Pharmacology

and Computations

CARDIAC GLYCOSIDES: DIGOXIN (LANOXIN)

Action: Inhibits the sodium-potassium pump, thus increase intracellular calcium, which causes the cardiac muscle fibers to contract more efficiently. 4 Effects on Heart Muscle:1) Positive inotropic action (Increase Myocardial Contraction).2) Negative chronotropic action Decreases heart rate).3) Negative dromotropic action (Decrease conduction of the heart cells).4) Increased stroke volume.


Indication:> To treat Congestive Heart Failure.> To slows down Atrial fibrillation and Atrial flutter.

Availability: Tablet 0.25 mg tablet Ampule 0.25mg / 2ml for intravenous use

Antidote: Digoxin immune fab (Digibind). Onset is 30mins and duration of action is 3-4days.

Therapeutic serum levels: 0.5 to 2.0 ng/ml (Lower serum level for CHF & Higher serum level for Atrial Flutter and Atrial Fibrillation, A-tach)

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Signs of Digoxin Toxicity: (Anorexia, Diarrhea, Nausea, Vomiting, Bradycardia, Cardiac dysrhythmias, Visual Disturbances)

•Hold for Cardiac Rate less than 60 bpm.•Watch out for:

•Hypokalemia•Hypomagnesemia•Hypocalcemia (may predispose toxicity0

NITRATES

Action: Act directly on the smooth muscle of blood vessels, causing relaxation and dilatation.

Increase blood flow thereby: A) Increasing oxygen supply. B) Decreasing oxygen demand by the myocardium.

Availability:- Isosorbide Mononitrate (Imdur) 30 mg and 60mg tablets- Isosorbide Dinitrate (Isoket 10mg / 10ml ampule. - Isordil 5mg tablets given sublingually).- Nitroglycerin (Deponit 5mg or 10mg patch, Transderm Nitro 5mg Patch).- Glyceryl tinitrate (Nitronal Aqueous) 10mg /10 ml ampule.

NITRATES

Side Effect: Headache (Most common). Decrease in BP

Reminders regarding Nitroglycerin sublingual tabletsA) No more than 3 tablets should taken in a 10 minute period (one tablet every 5 minutes 0-5-10).B) Offer sips of water before giving sublingual nitrates – dryness of mouth may inhibit drug absorption.C) Store in original glass container in a cool place, date bottle when opening and discard after 3 months.D) When carrying it place it in a bag not in the pocket (body temperature.

ANTI – ANGINA DRUGS

Trimetazidine• Action: Improves myocardial glucose utilization through inhibition of fatty acid metabolism. • Preparation: Vastarel MR 35mg tablet, Vastarel 20mg/tablet.

Ivabradine• Action: The first selective sinus node If channel inhibitor in the treatment of stable angina. Inhibiting If controls spontaneous electrical pacemaker activity in the sinoatrial node which determines heart rate that reduces myocardial oxygen demand, simultaneously improving oxygen supply.• Preparation: Coralan 5mg and 7.5mg could be given twice a day.

ANTI – HYPERTENSIVE DRUGS

BETA BLOCKERS

• Action: Block the beta1 receptor site thus decrease the effects of the sympathetic nervous system by blocking the release of the catecholamines, epinephrine & norepinephrine thereby decreasing the heart rate & blood pressure.•Indication: Long term prevention of angina, Treating Hypertension and is an anti-arrhythmic.

•Beta 1: Heart / Cardiac, Beta 2: Bronchi

A) Selective Beta Blockers (Beta 1) Atenolol (Tenormin) 50 mg

B) Non –selective Beta blockers (Beta 1 & 2) Metoprolol Tartrate (Betaloc) 50 mg and 100 mg tabletsCarvedilol (Dilatrend) 6.25mg and 25 mg tablets


BETA BLOCKERS


CALCIUM CHANNEL BLOCKERS

Indication: Prevention of angina and control of hypertension.Action: Prevent passage of calcium ions across the myocardial cell membrane and vascular smooth muscle cells. Thus dilation of coronary and peripheral arteries, results in decrease force of heart contraction and reduces the workload.

Preparation: Amlodipine (Norvasc) 5mg and 10 mg tablets,Isoptin (Verapamil HCI) 5mg per 2 ml ampule and 40 mg& 80 mg tablet, Felodipine (Plendil ER) 2.5mg, 5mg and 10mg tablet, Cardipine (Nicardipine) 10mg/10ml ampule.


ANGIOTENSIN CONVERTING ENZYME (ACE) BLOCKERS

Action: Inhibit ACE that in turn inhibits Angiotensin II (Vasoconstrictor) and block the release of aldosterone (Aldosterone: promotes sodium retention and potassium excretion)Side effect: Cough

Examples: Captopril (Capoten) 25mg and 50mg Tablets, Imidapril HCI (Vascor) 5mg and 10mg tablets, Enalapril maleate (Renitec) 5mg, 10mg ,20mg

Tritace (Ramipril) 2.5 mg, 5mg &10mg tablets


ANGIOTENSIN II RECEPTOR BLOCKERS

Action: Inhibits block the action of Angiotensin II by attracting to tissue binding receptors sites.

Example: Losartan Potassium (Cozaar) 50mg and 100mg / tab Vasaltan (Diovan) 80mg and 160mg / tab Telmisartan (Micardis) 40mg and 80 mg / tab Approvel (Irbesartan) 150mg and 300 mg / tab

* Does not cause cough which are associated with ACE inhibitors


SODIUM NITROPRUSSIDE

Indication: Reduction of blood pressure of patients in hypertensive crises.

Action: relaxation of vascular smooth muscle and consequent dilatation of arteries and veins.

Dilution: Solution containing 50 mg of Nitroprusside must be further diluted in 250-1000 mL of sterile 5% dextrose.

REMINDER: Drug solution should be protected from direct light, Use carbon paper or aluminum.


SODIUM NITROPRUSSIDE

Dosage: (0.3 mcg.kg/min – 10 mcg . kg / min). Started on low dose to avoid Hypotension

Side Effect: Severe Hypotension and Cyanide Toxicity.

NOTE: Sodium nitroprusside infusions at rates above 2 mcg/kg/min generate cyanide ion (CN¯) faster than the body can normally dispose of it. Cyanide toxicity can be a problem and can lethal.

N> protect solution from sunlight

Cyanide toxicity 60 mg/L(initially tinnitus, miosis, hyperreflexia)

Severe cyanide toxicity 200 mg/L(air hunger, confusion, Lactic acidosis, death)

N> Report immediately if with headache, nausea, pain at insertion site)

Sodium Nitroprusside


CENTRAL ALPHA 2 ANGONIST

Action: Stimulates alpha-adrenoreceptors in the brain stem. This action results in reduced sympathetic outflow from the central nervous system and it decreases peripheral resistance, renal vascular resistance, heart rate and blood pressure.

Preparation: Clonidine (Catapres) 75mg and 150mg tablets and 150mcg/ml ampule.

NOTE: Enhanced Anti-Hypertensive effect by Diuretics. Vasodilators and Beta Blockers.


DIRECT RENIN INHIBITORAction: Inhibits renin that directly blocks the conversion of angiotensinogen to angiotensin I which decreases the formation of angiotensin II which is a potent blood pressure elevating peptide.

Preparation: Aliskerin 50mg to 300mg once a day

Adverse reaction: Hyperkalemia, Increase BUN, uric acid, dizziness, cough and Diarrhea.

Bago-bago itong gamot na ito!!!

ANTI – COAGULANTS – ANTI PLATELETS

HEPARIN SODIUM (HEPARIN LEO)

Action: Delays release of reactivated thromboplastin, delaying formation of prothrombin to thrombin.

> A natural substance in the liver that prevent clot formation

Effect: Prolongs clotting time, and partial thromboplastin time (PTT) and activated partial thromboplastin time (APTT).

> Can decrease platelet count and cause Thrombocytopenia.

ANTIDOTE: PROTAMINE SULFATE

Preparation: 1000 units per ml, 5ml vial

Indication: Treatment of MI, Pulmonary Embolism, Prevention of clotting in arterial and heart surgery


LOW MOLECULAR WEIGHT HEPARIN (PRE-FILLED SYRINGES)Action: Bind to anti-thrombin III which inhibits the synthesis of Factor X and formation of Thrombin.

Duration of Treatment: Administered subcutaneously 7-14 days treatment duration.

Indication: Prevent Thromboembolitytic conditions such as Pulmonary embolism.

Contraindication: Strokes, Peptic ulcers and Blood anomalies


LOW MOLECULAR WEIGHT HEPARIN (PRE-FILLED SYRINGES)

Nursing Intervention / Reminders:A)Check for Bleeding, Eechymosis and Bruising around the site of injectionB)Reminder: Instruct the patient not to massage the site of injection.

Preparations:Enoxaparin Sodium (Clexane) 20mg, 40mg, 60mg, 80mg PFSFondaparinux Sodium (Arixtra) 2.5 mg / PFS


COUMADIN (WARFARIN SODIUM)

Action: Inhibit hepatic synthesis of vitamin K delaying prothrombin synthesis in the liver.

Indication: Used in chronic Atrial Fibrillation patients to prevent Cerebrovascular accident.

Physiologic Effect: Prolongs clotting time and monitored by Prothrombin time (PT) = should be 1.5 to 2 times the reference value to be therapeutic.Labworks monitoring: PT and INR

ANTIDOTE: Phytonadione (Vitamin K)


ASPIRIN

> Oldest non-narcotic analgesic drug still in use.

4 Effects1. Analgesic2. Antipyretic3. Anti-inflammatory4. Decrease platelet aggregation

Action: Blocks the formation of Prostacyclin and Thromboxane A2 in platelets producing an inhibitory effect of platelet aggregation.

Side effect: Gastrointestinal discomfort, Bleeding


CLOPIDOGREL

Action: Provides an irreversible blockade of the adenosine diphosphate (ADP) receptor on platelet cell membranes. Named P2YI2 (important in platelet aggregation the crosslinking of platelet by fibrin) inhibits platelet aggregation by blocking activation of glycoprotein IIb / IIIa pathway.

Preparation: Plavix 75mg per tablet Winthrop 75mg per tablet

TIROFIBAN (AGGRASTAT)


Action / Classification: Glycoprotein (GP) IIb / IIIa antagonist

Indication: Acute Coronary Syndrome and patient’s undergoing PTCA.

Usual Dilution: 12.5 mg in D5W 200ml• Tirofiban has a rapid onset and short duration of action after proper IV administration. Coagulation parameters turn back to normal 4 to 8 hours after the drug is withdrawn.

Why is it used in patient’s undergoing and Post PTCA?

> Decreases the rate of refractory ischemic conditions, new myocardial infarction and death.

THROMBOLYTICS

Action: Promotes the fibrinolytic mechanism (converting plasminogen to plasmin, which destroys fibrin in the clot).

Example: Streptokinase (Streptase) and Tissue plasminogenactivator (t-PA).

Effective if administered within 6 hrs following an acute MI.

Antidote for excessive bleeding: Aminocaproic acid (Amicar)

Side effect: Hemorrhage

Streptokinase

Group C betahelolytic streptococcal nonenzymatic protein

N> watch out for bleedingN> before administering, have a standby Hydrocortisone and Amicar

Test dose is 100 international units intradermal

Dose for M.I.

1.5 million u.i. oer 1 hour per IV route

HAEMOSTATICS / ANTI FIBRONOLYSIS AGENT

AMINOCAPROIC ACID (AMICAR)

• Indication: Used to treat excessive postoperative bleeding, especially after procedures in which a great amount of bleeding is indicated, such as cardiac surgery.

• Side effect: Bradycardia, Hypotension, Abdominal pain• Contraindication: Patient’s with Hematuria (Amicar is known to cause intrarenal obstruction in the form of glomerular capillary thrombosis or clots in the renal pelvis and ureters).

• Action: inhibition of plasminogen activators and to a lesser degree through antiplasmin activity.

ANTI - ARRHYTHMICS

Class 1A: Sodium Channel Blockers

Action: Prolong the action potential by depressing the phase 0 of depolarization – repolarization cycle and prolongs the time a cell needs to completely depolarize.

Indication: Atrial flutter or Fibrillation, Paroxysmal Supraventricular tachycardia, PVC’s.

ECG : Slightly Widened QRS, Prolonged QT interval, flattened or inverted T waves.

ANTI - ARRHYTHMICS

Class 1B ANTI-ARRHYTHMIC

Action: Depress the phase 0 and shorten phase 3 repolarization of action potential.

Effect: Decrease ventricular automaticity and control ventricular dysrhythmias.

Indication: ventricular arrhythmias.

ECG: Shortened QT interval, Shortened PR interval.

Example: Lidocaine, Tocanide (Tonocard).

ANTI - ARRHYTHMICS

Class 1C ANTI-ARRHYTHMIC

Action: Slow the sodium channel and depress phase 0.

Indication: Paroxysmal Atrial Fibrillaiton or Flutter, Ventricular Tachycardia.ECG: prolonged QT interval, lengthened PR interval, widened QRS complex.

Example: Encainide, Flecainide (Tambocor) and propafenone.

ANTI - ARRHYTHMICS

Class II: Beta Adrenergic Blockers

Action: Depress phase 4 depolarization and slow SA node impulse.

Indication: Supraventricular and Ventricular Arrhythmias.

ECG : slightly shortened QT interval, slightly lengthened PR interval, decreased HR.

Example: propranolol, esmolol .

ANTI - ARRHYTHMICS

Class III: Potassium Channel Blocker

Action: Prolong the phase 3 of the action potential - increase the action potential duration without affecting conduction time or depressing cardiac contractility..Indication: Supraventricular Tachycardia, Atrial Flutter,

Atrial Fibrillation.ECG: widened QRS, prolonged QT interval.

Example: Amiodarone (Cordarone)

ANTI - ARRHYTHMICS

Class IV: Calcium Channel Blocker

Action: Depress phase 4 depolarization and lengthens phase 1 and 2 of repolarization.Indication: SVT, Atrial fibrillation or Atrial Flutter.

ECG: lengthened PR interval, decreased HR.

Example: Verapamil & Diltiazem.

ANTI - ARRHYTHMICS

UNCLASSIFIED: ADENOSINE

Action: Acts on AV node to slow conduction system.

Indication: Supraventricular tachycardia.

ECG: Short asystolic pause at the time of conversion

Rapid onset: 1-2 minutes

Administration of drug: Administer: Adenosine 6mg in over 1-2 seconds followed by administration of 20ml normal salinesolution flushing. (Half life is less than 10 seconds)

Contraindication: 2nd or 3rd degree AV block or sick sinus syndrome, Atrial flutter, Atrial fibrillation.

ANTI - ARRHYTHMICS

UNCLASSIFIED: ATROPINE

Action: Anticholinergic drug that blocks vagal effects of SA and AV node.

Indication: Symptomatic bradycardia and Asystole.

ECG changes: Tachycardia (High doses) Bradycardia (if given slowly or low dose less than 0.5 mg)

Maximum dose: 3mg

ANTI - ARRHYTHMICS

UNCLASSIFIED: MAGNESIUM SULFATE

Indication: - Treatment of choice for Torsades de Pointes- Correction of Hypomagnesemia which is associated with the development of Atrial and Ventricular arrhythmia.

Dosage: Intravenous infusion: 1 to 2 gram diluted in 50 to 100ml IV fluid.

Side effect: Flushing, sweating, sharply lowered blood pressure, hypothermia, stupor and ultimately, respiratory depression.

PRESSORS / INOTROPS

DOPAMINE

Indication: correction of hemodynamic imbalances present in the shock syndrome due to myocardial infarctions, trauma , open heart surgery, renal failure, and chronic cardiac decompensation as in congestive failure.

Action: produces positive chronotropic and inotropic effects on the Myocardium, resulting in increased heart rate and cardiac contractility.

Usual IV infusions (mg of Dopamine in ml of fluid)200mg / 100ml 200 mg / 250 ml400mg / 250 ml 400 mg / 100mlDiluents: NSS, ½ NSS, D5W, LR

PRESSORS / INOTROPS

DOPAMINE

Initial Effect: 5 minutes

Dose: 1mcg/kg/min – 20 mcg/kg/min. Maybe increased greater than 20 mcg/kg/min but with the judgment of the doctor. Initial dose usually at 2-5 mcg/kg/min

Titrate 1-4 mcg/kg/min at 10-30 mins. interval

Dopamine renal dose (3 mcg/kg/min) – dilates renal and mesenteric blood vessels, producing an increase in urine output (Dopamenergic effect).Beta dose (3-10 mcg/kg/min)Alpha dose (10-20 mcg/kg/min)

PRESSORS / INOTROPS

DOBUTAMINE

Indication: Inotropic support in the short-term treatment of adults with cardiac decompensation due to depressed contractility resulting either from heart disease or from Cardiac surgery.

Action: Primary activity results from stimulation of the β receptors of the heart while producing comparatively mild chronotropic, hypertensive, arrhythmogenic, and vasodilative effects.

Initial effect: 1-2 mins

PRESSORS / INOTROPS

DOBUTAMINE

Usual infusions250mg / 100ml500 mg / 100ml250 mg / 250 ml500mg / 250 ml

Dose: 2mcg/kg/min – 20 mcg/kg/min. Maybe increased greater than 20 mcg/kg/min but with the judgment of the doctor.

May use D5W or NSS

Incompatible with alkaline sol’n (NaHCO3)

PRESSORS / INOTROPS

NOREPINEPHRINE

Indication: An adjunct in the treatment of cardiac arrest and profound hypotension.

Action: A peripheral vasoconstrictor (alpha-adrenergic action) and as an inotropic stimulator of the heart and dilator of coronary arteries (beta-adrenergic action).

PRESSORS / INOTROPS

NOREPINEPHRINE

Dose: 4 mg -32mg in D5W 100 or 250Stock dose: 4mg / 4ml ampule

Max dose: 30 mcg / 3000 nanograms /kg/min

PRESSORS / INOTROPS

EPINEPHRINE (ADRENALINE)

Action and Effect: Cause bronchodilation, enhanced cardiac performance and vasoconstriction to increase blood pressure.

Route: E.T., IV Push and Infusion

* Used also as the drug of choice for anaphylactic shock.

Side effect: Monitor for: Tachycardia cardiac arrhythmia, palpitation and hypertension.

Intracardiac 1:10,000 (0.1 mg/mL) solution: 0.3 to 0.5 mg (3 to 5 mL). This route should only be used if there is insufficient time to establish an IV route and should only be administered by personnel well trained in this technique.

STATINS

Classification: HMG-COA reductase inhibitors Action: Lowers cholesterol by inhibiting HMG-COA that reduces low density lipoprotein (LDL) cholesterol and total cholesterol. Also causes a moderate reduction in triglyceride levels and small increase in levels of HDL cholesterol

Helps patients with Coronary Artery Disease by reducing the size of plaques in the arteries.

Side effects: Increase Liver EnzymesAtorvastatin (Lipitor) Lovastatin Pravastatin Rosuvastatin (Crestor)Fluvastatin Simvastatin (Vidastat / Zocor)

DIURETICS

2 Main Purposes of Diuretics:A) Decrease hypertensionB) Decrease edema (peripheral and pulmonary) in Congestive heart failure, renal and liver disorder.

Action: Produces increased urine flow (dieresis) by inhibiting sodium and water re-absorption from the kidney tubules.

Concern if using Diuretics: Electrolyte: Imbalance especially Hypokalemia.

3 Categories of Diuretics that as used for Cardiac cases

DIURETICS

A) Thiazides – acts on distal convoluted renal tubule, beyond the loop of henle. To promote sodium, chloride (Hypercalcemia can occur). E.g. Chlorothiazide (Diuril)

B) Loop (High Ceiling) Diuretics – act on the ascending loop of henle by inhibiting chloride transport of sodium into the circulation. It is 2-3 times more effectively in inhibiting re-absorption of sodium / saluretic (sodium losing) effect. E.g. Furosemide (Lasix).

DIURETICS

C. Potassium-Sparing diuretics – weaker than thiazides and loop diuretics. Used as mild diuretics or in combination with another diuretics and acts primarily in the collecting distal duct renal tubules to promote sodium and water excretion and potassium retention. E.g. Spinorolactone (Aldactone).

PERIPHERAL VASODILATORS

CILOSTAZOL

Preparation: Pletaal 50mg and 100mg tablets.Indication: Intermittent Claudation (condition caused by narrowing of the arteries that supply the legs with blood).

Action and Effect: Reduces the pain of intermittent claudication by dilating the arteries, thereby improving the flow of blood and oxygen to the legs. (It does this by decreasing the action of an enzyme, phosphodiesterase III.)

Contraindication: Heart Failure

PERIPHERAL VASODILATORS

Preparation: Trental, Intravenous drip: 300mg vial in D5W 100ml, Per orem 400mg tablets.

PENTOXYFILLINE

Indication and Action: Decreases the "stickiness" (viscosity) of blood and thereby improves its flow through arteries. This increases the flow of blood and oxygen to muscles and helps patients with intermittent claudication.

Dexmedetomidine (Precedex)

Alpha 2 agonist used for sedation (the first)

exhibits a rapid distribution phase with a half-life of about 6 minutes.

A loading infusion of 1 mcg/kg over a 10-minute period provides onset of sedation typically w/in 10 to 15 minutes after the start of the infusion.

For ICU sedationMaintenance dosing of Precedex is initiated at 0.4 mcg/kg/hr and titrated over a dose range of 0.2 to 0.7 mcg/kg/hr.

For sedation during surgical and other proceduresAfter administration of a 1 mcg/kg loading dose, the maintenance dose of Precedex is initiated at 0.6 mcg/kg/hr and titrated to achieve the desired clinical effect, with doses ranging from 0.2 to 1 mcg/kg/hr.

Mcg / kg / min ??????

DOSAGE AND CALCULATIONS

mcg/kg/min used in Dopamine, Dobutamine, Na Nitroprusside

ng/kg/min used in Norepinephrine (Levophed)

ml/hour used as flow rate

mg/hour used in drugs like Isoket, Lasix

Total fluid rate (“TFR”) is the total ml/hour of all iv fluids

Mcg/kg/hour is used in precedex

1 mg= 1000mcg= 1,000,000ng1 mcg= 1000 ng1 mcg= 1ug (not used due to unsafe abbreviation)1ml= 1cc (preferred to be used for gases instead of liquid)


MG / HR

Problem:

A patient is with an IVF of Isoket 10 mg in PNSS 90If the Isoket drip is at 12 ml/hr. How many mg/hr is thePatient receiving?

IV INCORPORATION


Problem:

How many ml of KCL will you incorporate to an IVF fluid of PNSS 80ml if the Doctor ordered 30 meqs Potassium Replacement?


DOPAMINE AND DOBUTAMINE COMPUTATION

Drop factordose in mg X 1000 mcg/mg diluents in ml X 60 min/hr Mcg/kg/min ml/hr X drop factor weight Ml/hr mcg/kg/min X weight drop factor

Problem:

Given are Dobutamine 500 mg in D5W 100 to run at 10 ml/hr. Patient’s Weight is 70kg. How many mcg/kg/min is the Dobutamine drip running at?

Drop factordose in mg X 1000 mcg/mg diluents in ml Mcg/kg/hour ml/hr X drop factor weight Ml/hr mcg/kg/hour X weight drop factor

Precedex

200 mcg of precedex in NSS 100 to run for 7 ml/hour.

Weight 65kg

Compute for mcg/kg/hour?

Concentrationmcg = stock (mg) X 1000 IVF 60 Dose: ng/kg/minng/kg/min = flow rate (ml/hr) X concentration X 1000ng wgt in kg 1 mcg

Flowrate:Ml/hr = dose (ug/kg/min) X weight 1000 Concentration

LEVOPHED COMPUTATION


LEVOPHED COMPUTATION


Problem:

A patient has an IVF of Levophed 16 mg in D5W250.How many nanograms is the levophed running at if it is currently running at 14 ml/hr? Weight is 65 kg.


Heparin1. Units/h= total units of heparin no. of hours to infuse2. Cc/hr= units/h X IV diluents total units of heparin3. Units/cc= total units of heparin IV diluents

Problem:

How many ml/hr will the HeparinDrip be running if the drip is set 20000 units to run for 24 hours in1000ml IV fluid?

HEPARIN COMPUTATION

pharmacology revised

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