Commonly Used Medications

Mikhail C.S.S. Higgins

Krishna Kandarpa

Michael A. Bettmann

Analgesics

Lidocaine Hydrochloride (Xylocaine)

Mode of Action

Stabilizes neuronal membrane, preventing initiation and conduction of nerve impulses

Adverse Reactions

1. Drowsiness is an early sign of high blood level of lidocaine due to inadvertent intravascular administration or rapid absorption of the drug.

2. Nervousness, dizziness, blurred vision, tremors, seizures (usually of short duration), and possibly respiratory arrest

3. Hypotension, bradycardia, and cardiovascular depression are dangerous late signs.

4. Intra-articular infusion is associated with chondrolysis post-arthroscopic/surgical intervention.

Preparation

1. For local subcutaneous infiltration: 1% to 4% solution, maximum dose 7 mg per kg with epinephrine, 4.5 mg per kg without, up to 300 mg (30 mL of 1% solution)

2. For use with chemoembolization: Use 2% Xylocaine solution which has 20 mg per mL of anhydrous active lidocaine hydrochloride (HCl). Mix 10 mL of 2% Xylocaine (without epinephrine) in 100 mL contrast, giving one an effective concentration of 2 mg per mL.

Dosage and Method

1. Percutaneous infiltration: Start with small subcutaneous/intracutaneous wheal and then subcutaneous infiltration, with aspiration prior to each injection to avoid intravascular injection. Addition of epinephrine aids in limiting dispersion of the lidocaine.

2. As additive to contrast: See item 2 in “Preparation”

Kinetics

Metabolized by the liver and excreted by the kidney. Local anesthetic effect and duration depends on volume and concentration infiltrated. Plasma half-life is approximately 2 hours.

Reversal

Treatment of toxic manifestations: Maintain patent airway and ventilation. Support circulatory system with intravenous (IV) fluids and vasopressors as required. Treat convulsions as necessary.

Opioids (see Table e-94.1)

Butorphanol Tartrate (Stadol)

Mode of Action

Potent synthetic phenanthrene type opioid agonist-antagonist analgesic, with antagonist activity 1/40 that of naloxone

Contraindications

1. Hypersensitivity to drug

2. Stadol should be avoided in individuals who are dependent on narcotics as symptoms of withdrawal may occur.

3. Once Stadol has been administered, the effects on an opioid agonist (e.g., morphine) are unpredictable due to its weak antagonistic effect at the supraspinal narcotic receptors.

Table e-94.1 Relative Opioid Potency (Equivalent Parenteral Dose)

Agonists
	MSO₄	10 mg
	Methadone	10 mg
	Hydromorphone (Dilaudid)	1.5 mg
	Fentanyl	1.00-200 µg
	Levorphanol	2 mg
	Codeine	130 mg
	Meperidine (Demerol)	75-100 mg
Agonist-Antagonists
	Nalbuphine (Nubain)	10 mg
	Dezocine (Dalgan)	10 mg

Adverse Reactions

1. Sedation (40% of patients), nausea (6%), diaphoresis (6%)

2. Respiratory depression (2 mg Stadol = 10 mg morphine); however, the magnitude of respiratory depression does not increase beyond a dose of 4 mg.

3. Increases load on the heart and therefore should be avoided, if possible, in patients with acute myocardial infarctions (MIs) and patients with ventricular or coronary insufficiency

Preparation

Available in 1-mL disposable syringe, with 2 mg per mL

Dosage and Method

1. Premedication may be given on floor: 1 to 2 mg Stadol intramuscular (IM) with

25 to 50 mg Vistaril IM.

2. Titration to desired effect in angiography suite: Administer 0.5 mg IV slowly and every 15 minutes (while assessing patient’s response) up to a dose of 2 mg.

3. After adequate analgesia has been established, additional 0.5 mg increments of

Stadol may be given every 30 minutes up to a total of 6 mg, depending on the patient’s size, age, and level of debilitation.

4. It is difficult to “catch up” with pain; thus, adequate pre- or early administration of medication is the key.

Kinetics

Rapid onset of action (10 minutes) and early peak analgesia (30 minutes) following IV administration. Duration of action is 3 to 4 hours.

Reversal

1. Naloxone (Narcan): 0.1 to 0.2 mg per dose over 2 to 3 minutes; titrate to desired effect (adequate ventilation, alertness).

2. General supportive therapy including oxygen, IV fluids, and vasopressors, as necessary

Fentanyl Citrate (Sublimaze)

Mode of Action

Short-acting synthetic opioid with rapid onset of action

Adverse Reactions

1. Respiratory depression (peaks at 5 to 15 minutes). Administer O₂ by nasal cannula and use capnography during procedure.

2. Bradycardia (depends on dose and rate of injection; prophylactic atropine prevents bradycardia)

3. Nausea

4. Dizziness

5. Bronchoconstriction and laryngospasm

6. Muscle rigidity causing stiff-chest syndrome: occurs with rapid injection especially in elderly patients. Muscle relaxants are useful for treatment.

7. Hypertension resulting from administration in patients receiving MAO inhibitors within 14 days (managed by use of vasodilators and β-blockers)

Preparation

Available in 2-mL and 5-mL ampules (both: 50 µg per mL)

Dosage and Method

1. Load: 25 to 100 µg IV over 1 to 2 minutes

2. Maintenance: 25 to 100 µg every 30 minutes (as needed for pain control)

3. Maximum dose: 3 µg/kg/h

4. Equivalence: 100 µg fentanyl = 10 mg morphine = 100 mg meperidine

5. Monitor vital signs. Hold maintenance dose if there is any change in blood pressure or heart rate > 20%, or if respiratory rate is < 10 breaths per minute.

6. Decrease dosage appropriately for elderly and debilitated patients.

Kinetics

When administered intravenously, onset of action is immediate (2 to 5 minutes), but maximum analgesia and respiratory depression take several minutes (about 15 minutes). Duration of action for single IV dose of 100 µg (0.1 mg or 2 mL) is 30 to 60 minutes.

Reversal

1. Respiratory support with oxygen administration and maintenance of patent airway

2. General supportive care

3. Naloxone (Narcan): 0.1 to 0.2 mg per dose over 2 to 3 minutes; titrate to desired effect (adequate ventilation, alertness without significant pain or discomfort).

4. Note: The duration of respiratory depression following overdosage may exceed duration of action of the narcotic antagonist. Continue capnography monitoring until full reversal.

Meperidine Hydrochloride (Demerol)

Mode of Action

A synthetic opioid analgesic

Adverse Reactions

1. Tachycardia following IV injection (anticholinergic effect)

2. Respiratory depression (effect equal to morphine sulfate)

3. May lower seizure threshold

4. Light-headedness, dizziness, sedation, nausea, vomiting, and sweating, although less than with morphine sulfate

5. Orthostatic hypotension, similar to morphine sulfate

6. Lesser rise in biliary pressure than morphine sulfate

7. Urinary retention (rare)

8. Urticaria, drug rash (rare)

Preparation

Available in 100-mg injectable cartridge needle

Dosage and Method

1. Titrate up to 0.5 to 1.0 mg per kg. During the procedure, fractional doses (10 mg) may be repeated every 30 minutes to 1 hour as needed by the patient. Meperidine has a shorter duration and one-tenth the analgesic potency of morphine sulfate.

2. As premedication: 50 to 100 mg IM, 30 to 45 minutes before procedure

Kinetics

Onset of action (3 to 5 minutes after IV injection) is slightly more rapid than morphine sulfate and duration is slightly shorter (2 to 4 hours). Redistribution half-life is about 7 minutes; elimination half-life is about 4 hours. Metabolized by the liver.

Reversal

1. Maintain adequate airway.

2. General supportive therapy and monitoring

3. Naloxone (Narcan): 0.1 to 0.2 mg per dose over 2 to 3 minutes; titrate to desired effect (adequate ventilation, alertness).

4. Oxygen, IV fluids, vasopressors as needed

Morphine Sulfate (MSO₄)

Mode of Action

Phenanthrene narcotic analgesic, naturally occurring opiate

Adverse Reactions

1. Respiratory depression (reduces brainstem response to carbon dioxide)

2. Convulsions (high IV dose)

3. Nausea and vomiting

4. Causes rise in common bile duct pressure, decrease in gastric emptying, decreased colonic tone, bronchoconstriction, and urinary retention

5. Orthostatic hypotension without significant change in cardiac rate, rhythm, or output

Preparation

Multiple, generally as 1 mg per mL. Available in disposable syringe as 10 mg per 10 mL

Dosage and Method

1. Give 2 to 3 mg IV per dose, slowly over 1 minute (titrate monitoring vital signs; maximum dose, 10 mg per hour for a 70-kg patient or not to exceed total dose of 0.2 mg per kg).

2. Hold maintenance dose if there is any change in blood pressure or heart rate > 20%, or if respiration rate is < 10 breaths per minute.

3. As premedication: 1 mg per 10 kg IM. Administer with extreme caution in elderly or debilitated patients.

Kinetics

1. Rapid onset of action (5 to 7 minutes) with peak analgesia about 20 minutes after IV injection

2. Analgesia and respiratory depression last several hours depending on dose (3 to 4 hours).

3. Elimination half-life: 1.5 to 2.0 hours. Major metabolic pathway is via conjugation with glucuronic acid in the liver. Ninety percent of intravenously administered morphine is eliminated via the urine in 24 hours.

4. About 10% of the administered dose is eliminated in the feces.

Reversal

1. Maintain adequate airway.

2. General supportive measures: Monitor vital signs, fluid input/output.

3. Naloxone (Narcan): 0.1 to 0.2 mg/dose over 2 to 3 minutes; titrate to desired effect (adequate ventilation, alertness without undue pain). Duration of effect is 30 to 45 minutes; therefore, patient must be monitored for 1 to 2 hours.

Nalbuphine Hydrochloride (Nubain)

Mode of Action

Potent synthetic phenanthrene opioid narcotic agonist-antagonist analgesic

Adverse Reactions

1. Excessive sedation

2. Nausea and vomiting

3. Dizziness

4. Restlessness

5. Limited analgesia

6. Reversal of analgesia produced by other opioids.

7. In nondependent patients, may show additive effect with other narcotics; reduce dose of drugs.

8. Respiratory depression. Use in low doses and cautiously in patients with respiratory problems.

9. Bradycardia

Preparation

Available in 1-mL ampules at 10 mg per mL

Dosage and Method

1. Give 5 to 10 mg IM, or

2. Give 1 to 3 mg IV.

3. Maximum recommended for pain relief is 10 mg for a 70-kg adult. May be repeated every 3 to 6 hours.

Kinetics

Onset of action is within 5 minutes of IV injection, and 15 minutes of IM or subcutaneous (SC) injection. Plasma half-life: 5 hours. Duration of analgesia: 3 to 6 hours. Metabolized in the liver, excreted by the kidneys.

Reversal

1. Naloxone or nalmefene (Selincro)

2. Resuscitative equipment must be available.

3. Oxygen and supportive measures

Antibiotics

Current indications and doses for antibiotic prophylaxis in interventional procedures are listed in Table e-94.2.

Anticoagulants

Heparin

Mode of Action

Multiple interactions. Main action is reversible combination with antithrombin III to inactivate thrombin, a coagulation protein, thus preventing conversion of fibrinogen to fibrin; does not directly lyse existing clot. Also affects multiple other coagulation factors (e.g., Factor Xa) and platelets.

Contraindications

1. Heparin-induced thrombocytopenia (HIT) is defined as a 50% decrease in platelet count. Incidence: 10% to 20%. This is thrombocytopenia without significant associated symptoms, and heparin may be continued with caution.

2. Heparin-induced thrombocytopenia with thrombosis (HITT): 5% to 10% incidence, often with longer use. An immune-mediated, allergic reaction requiring cessation of heparin use. Antibodies may disappear after 1 year, so heparin may be cautiously restarted. Can be characterized by uncontrollable bleeding and diffuse thrombosis.

3. Hemophilia

4. Bacterial endocarditis

5. Excessive ethanol intake

Adverse Reactions (see above)

1. Hemorrhage (3% to 8% of patients)

2. Acute thrombocytopenia

3. Systemic hypotension

4. Hypersensitivity, chills, fever, urticaria (2% to 5% of patients)

5. Vasospastic reactions

6. Osteoporosis and symptomatic vertebral fracture (2% to 3% of patients, with prolonged use)

7. Anaphylactic shock (rare)

Table e-94.2 Recommended Antibiotic Prophylaxis in Interventional Radiologic Procedures

Procedure		Suspected Organism(s)	Recommended Drug	Adult Dosage and Duration
Vascular system
	Diagnostic angiography	None	None	—
	Interventional (angioplasty, certain embolizations, infusion, etc.)	None	None	—
Biliary tract
	No clinical infection suspected	Enterobacteriaceae (includes Escherichia coli, Klebsiella, Enterobacter), enterococcus, Pseudomonas, Clostridium	Cefazolin	1 g IV/IM before and q8h for 48 hours
			or
			Cefoperazone	2 g IV/IM before and q12h for 48 hours
	Clinical infection suspected	Same as above	Cefoperazone (or other third-generation cephalosporin)	2 g IV/IM before and q12h (based on results of Gram stain and culture)^a
			or
			Ampicillin plus	2 g IV before and q6h (based on results of Gram stain and culture)^a
			Gentamicin	1.5 mg/kg IV before and q8h^a,b
	Outpatient procedure	Same as above	Ceftriaxone	1 g IV/IM (single dose)
Genitourinary system^b
	No clinical infection suspected	None	Cefazolin	1 g IV/IM before and q8h for 48 hours
			or
			Cefoperazone	2 g IV/IM before and q12h for 48 hours
	Clinical infection suspected	Enterobacteriaceae (includes E. coli, Klebsiella, Proteus, Enterobacter), enterococcus, Pseudomonas aeruginosa	Ampicillin plus	2 g IV before and q6h (based on results of Gram stain and culture)^a
			Gentamicin	1.5 mg/kg IV before and q8h^a,b
			or
			Ticarcillin or other ureidopenicillin	Consult product insert
Drainage of fluid collection
	Tap of “clear” fluid collection (renal or hepatic cyst, lymphocele)	None	None	—
	Known or suspected abscess	Enteric gramnegative bacteria, enterococcus, Bacteriaceae fragilis, other anaerobes	Cefoxitin	2 g IV before and q6h (based on results of Gram stain and culture)^a
			or
			Cefotetan	1 g IV before and q12h^a
			or
			Gentamicin plus metronidazole	1.5 mg/kg IV before and q8h^a,b 500 mg IV before and q6h^a
			or
			Gentamicin plus clindamycin	1.5 mg/kg IV before and q8h^a,b 900 mg IV before and q8h^a
Endocarditis prophylaxis^c
	Biliary, genitourinary, or gastrointestinal procedures that are not considered “clean”	Enterococcus	Ampicillin^d plus gentamicin	2 g IV before and q8h in for 48 hours 1.5 mg/kg IV before and q8h for 48 hours^b
^a These drugs are recommended as prophylaxis. Specific therapy should be instituted when clinically indicated and when results of cultures are available, in consultation with referring clinical staff. ^b Dose may require modification in the presence of renal insufficiency. Consult product insert. ^c Endocarditis prophylaxis recommended for the following cardiac conditions: prosthetic cardiac valves (including biosynthetic valves), most congenital cardiac malformations, surgically constructed systemic-pulmonary shunts, rheumatic or other valvular dysfunction, idiopathic hypertrophic subaortic stenosis (IHSS), previous history of bacterial endocarditis, and mitral valve prolapse with insufficiency. ^d When patient has penicillin allergy, substitute vancomycin, 1 g IV before and q12h for 48 hours. Modified from Spies JB, Rosen RJ, Lebowitz AS. Antibiotic prophylaxis in vascular and interventional radiology: a rational approach. Radiology. 1988;166:381-387.

Preparation

Mix 50,000 units of heparin in 500 mL of normal saline (NS) or 5% dextrose solution (D5W) (100 IU per mL) or in 50 mL D5W or NS (1,000 IU per mL).

Dosage and Method (Continuous IV Infusion)

1. Bolus: 5,000 U IV (2,500 to 5,000 U IV if < 70 kg)

2. Infuse: 800 to 1,500 U per hour (reduce rates for older patients, especially females)

3. Maintain activated partial thromboplastin time (APTT) at 1.5 to 2.5 times normal (normal = 25 to 35 seconds). Check APTT at 4 hours, then every 2 to 4 hours until therapeutic, and then four times per day (qid).

4. If using activated clotting time (ACT) during an intravascular procedure, adequate IV heparin should be administered (per above protocol) to achieve a minimum ACT of 300 seconds. In most cases, the ACT is maintained at 300 to 400 seconds by giving additional boluses as needed. ACT is less precise than APTT and lacks high correlation with it.

Kinetics

1. Onset: immediate (30 minutes to maximum activity)

2. Duration: 60 to 90 minutes in normal people (cleared by reticuloendothelial cells of the liver)

Reversal

To reverse heparin’s anticoagulant effect:

1. Prior to a planned procedure: Preferably stop infusion for 3 to 6 hours (or about three half-lives) and check anticoagulation status before the starting procedure.

2. After completion of an intravascular procedure: Administer IV protamine sulfate 10 mg per 1,000 U of heparin given during the procedure (drip slowly; use cautiously in diabetics taking neutral protamine Hagedorn [NPH] insulin; very high incidence of allergy to protamine among these patients, with possible anaphylaxis in up to 50%). Check if desired anticoagulation reversal has been achieved.

Warfarin Sodium (Coumadin)

Mode of Action

Inhibits hepatic synthesis of clotting factors II, VII, IX, and X, thereby preventing clot formation or extension of formed clot; does not directly lyse existing clot

Adverse Effects

1. Hemorrhage (3% of cases)

2. Hypersensitivity (rare)

3. Severe cutaneous reaction (rare but may be irreversible and fatal)

Preparation

Available for oral administration: 2 mg, 2.5 mg, 5 mg, 7.5 mg, and 10 mg. Dose is individually titrated to therapeutic prothrombin time (PT) or, more usually, international normalized ratio (INR): 2 to 3 for deep vein thrombosis (DVT)/pulmonary embolism (PE) treatment, 3 to 4 for atrial fibrillation (AF) prophylaxis, artificial cardiac prosthesis. Concomitant administration of heparin will affect PT.

Kinetics

1. Onset of action after loading dose: 2 to 7 days for fully effective anticoagulation

2. Duration: 4 to 5 days

3. Half-life: 2.5 days. Metabolites are primarily excreted through the urine.

Reversal

1. If an intravascular procedure is contemplated, it is best to discontinue Coumadin 3 to 5 days prior to an invasive procedure. If necessary, IV heparin may be given instead of Coumadin until 3 to 6 hours prior to the procedure. Acceptable INR for intravascular procedures is < 2.0.

2. Alternatively, prothrombin complex concentrate, fresh frozen plasma, or activated Factor VII may be given to urgently normalize INR. The onset is fast, and duration of action is limited. Nota bene: These will not generally lower INR below 1.5

3. Another option is to administer vitamin K, 25 to 50 mg IM, 4 hours prior to the procedure. Both onset of action and duration are prolonged. Unfortunately, it may take 1 to 3 weeks to reestablish acceptable anticoagulation with Coumadin after vitamin K reversal.

Newer Anticoagulants

Three categories: low-molecular-weight heparins (LMW heparins), synthetic direct factor inhibitors, and direct thrombin inhibitors. LMW heparins include enoxaparin (Lovenox), fondaparinux (Arixtra), and danaparoid.

I. LMW Heparins

These include Enoxaparin and Fondaparinux.

Mode of Action

1. Enoxaparin acts by irreversibly combining with Factor Xa.

2. Fondaparinux acts by reversibly combining solely with antithrombin III (ATIII).