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19: Basic Principles of Pharmacology
Abstract
A basic understanding of the pharmacology of medications used during perianesthesia care is necessary to ensure optimal outcomes in surgical patients. The use of a number of selective, potent drugs in various combinations represents the cornerstone of current anesthesia practice. Consequently, a comprehensive review of the principles and concepts of pharmacology is presented in this chapter. The specific actions and uses of drugs related to perianesthesia care are discussed. The pharmacology of individual drugs can be best understood in relation to the physiologic functions they affect and their common clinical applications.
Keywords
alpha-adrenergic agonist; alpha-adrenergic antagonist; anesthesia; anticoagulants; antiemetics; antihypertensive; beta-adrenergic agonist; beta-adrenergic antagonist; general anesthetics; herbal medications; neuromuscular blocking agents; neuromuscular blocking antagonists; opioids; pharmacology
A thorough understanding of the pharmacology of the medications used during perianesthesia care is necessary to ensure the best outcomes in surgical patients. Anesthesia care continues to evolve, and the use of a number of selective, potent drugs in various combinations represents the cornerstone of current anesthesia practice. Consequently, a comprehensive review of the principles and concepts of pharmacology is presented in this chapter. The specific actions and uses of drugs related to perianesthesia care are discussed in the physiology chapters within Section II, as are the concepts of anesthetic agents presented in Section III chapters. The pharmacology of individual drugs can be best understood in relation to the physiologic functions they affect and their common clinical applications.
The goal of anesthetic pharmacology is to provide unconsciousness (anesthesia), pain relief (analgesia), loss of memory (amnesia), and muscle paralysis. Current anesthesia practice employs polypharmaceutical approaches. Small doses of a number of specific receptor-active medications affords the clinician the ability to rapidly induce anesthesia and promote a speedy emergence in order to meet the flow of surgical and scheduling requirements in today’s modern operating environment. Because many varied drugs are used, significant drug interactions may occur. The important clinical interactions will be discussed in this chapter. Consideration must also be given to a patient’s existing medications including herbal agents and other over-the-counter preparations.1 Clinically, it is not uncommon for patients to take some form of herbal preparation.2 Consequently, knowledge of the principles of pharmacology becomes a meaningful and useful tool in the delivery of nursing care to the patient in the postanesthesia care unit (PACU).
Definitions
Additive Effect Occurs when a second drug with properties similar to the first is added to produce an effect equal to the algebraic sum of the effects of the two individual drugs. The shorthand often used to represent this is 1 + 1 = 2.
Agonists Drugs such as dopamine that attach to and activate specific receptors.
Antagonists Drugs such as naloxone (Narcan) that attach to a specific receptor and do not activate it but instead prevent an agonist or body chemical such as a neurotransmitter from stimulating the receptor.
Bioavailability The amount of drug (expressed as a percentage) that enters the blood in an unchanged form after administration. Will vary depending on the route of administration.
Competitive Antagonist Occurs when the concentration of the antagonist is higher than the agonist concentration. Results in reversal or antagonism of the agonist. Examples include naloxone (Narcan) competitively antagonizing or reversing fentanyl and flumazenil (Romazicon) reversing midazolam (Versed). The shorthand often used to represent this is 1 + 1 = 0.
Cross-Tolerance Existing tolerance to a drug because of a prior developed tolerance to a similar drug. For example, a patient who has developed a tolerance to morphine, because of repeated administration, will also require higher doses of all other opioids.
Efficacy of a Drug Refers to the maximum effect that can be produced by a drug.
Half-Life Generally refers to the elimination half-life, which is the time it takes the plasma concentration to fall by one half. It takes four to five half-lives to totally eliminate a drug.
Hyperreactivity An abnormal reaction to an unusually low dose of a drug. For example, patients with Addison’s disease, myxedema, or myotonic dystrophy react with a hyperreactivity to unusually low doses of barbiturates.
Hypersensitivity (Anaphylaxis) A drug-induced antigen-antibody reaction. The particular hypersensitivity reaction can be either an immediate (anaphylactic) or a delayed reaction. Hypersensitivity reactions can occur with succinylcholine, antibiotics, and many other drugs administered in the PACU (see Chapter 18).
Hyporeactivity An indication that a person needs excessively large doses of a drug to obtain a therapeutic or desired effect.
Idiosyncrasy An adverse drug reaction (not an allergy) that occurs in a small number of persons and has no correlation to dosage or type of therapy. An example is phenytoin-induced liver dysfunction.3
Mechanism of Action The means by which a drug exerts its effect on cells or tissues. Usually acting via a receptor.
Pharmacodynamics The study of drug mechanisms of action as well as other biochemical and physiologic effects on the body.
Pharmacokinetics The study of the movement of drugs throughout the body including the processes of absorption, distribution, biotransformation or metabolism, and excretion.
Potency of a Drug The necessary dose of a particular drug to produce a specific effect designated as the effective dose (ED). When that effect is achieved in a particular percentage of patients, it is quantified as ED50 for 50% of the patients and ED95 for 95% of the patients who show an effect from the drug.
Potentiation The enhancement of the action of one drug by a second drug that has no detectable action of its own. The shorthand often used to represent this is 1 + 0 = 3.
Receptors The portion on or within a cell, usually a protein complex, where the attachment of drugs leads to a physiologic response. The receptors are selective in that they recognize and uniquely bind to specific pharmacologic or physiologic agents.
Synergistic Effect Addition of a second drug to a drug with properties similar to the first that results in an effect greater than the algebraic sum of the effects of the two individual drugs. The shorthand often used to represent this is 1 + 1 = 3.
Tachyphylaxis An acute diminished response to a drug after successive doses requiring an increased amount to achieve a similar effect. For example, succinylcholine administered by intravenous drip. Over time, a higher drip rate is needed to achieve the necessary response.
Tolerance A type of hyporeactivity acquired during chronic exposure to a drug in which unusually large doses are needed to reach a desired effect. A prime example is a person who has become dependent on opioids and needs larger than normal doses to elicit the desired therapeutic response.
Drug responses
Drugs are given via a chosen route of administration at a specific dose with the expectation of a desired response. Many factors affect the time of onset, efficacy, and duration of action of a particular drug. The perianesthesia nurse must be aware of the basic principles of drug actions within a biologic system. A review of the basic concepts of drug responses is presented in this chapter, with particular emphasis on the patient in the PACU.
Pharmacokinetic actions
Pharmacokinetics is the pharmacology subspecialty that studies the absorption, distribution, metabolism, and elimination of a drug in the body. Consequently, pharmacokinetics can be viewed as what the body does to a drug after it is administered.
Systemic Absorption by Various Routes of Administration
Oral Route of Administration
When a drug is administered orally, it is absorbed in the small intestine, which has a large surface area. A drug must be lipid soluble to cross the gastrointestinal lining. After such absorption, the drug passes to the liver through the portal veins before it can enter systemic circulation. The liver extracts and metabolizes some of the drug in a process termed the first-pass hepatic effect. The drugs that are particularly subject to this effect are agents such as propranolol, metoprolol, verapamil, chlorpromazine, and morphine; therefore, these drugs are administered in much higher doses orally than intravenously.4
Oral administration of drugs in the PACU has some distinct disadvantages. For example, nausea and vomiting can occur, reducing the amount of the drug available for absorption by the small intestine. In addition, the absorption process can be affected because the gastric volume and pH are altered either by preoperative drugs or anesthesia and surgery.
Sublingual Route of Administration
The sublingual route of administration has several important advantages over the oral route because the sublingual route bypasses the first-pass hepatic effect. This route can be particularly favorable in the PACU for drugs such as nitroglycerin. A nitroglycerin tablet can be placed sublingually in an intubated patient as well as a cooperative awake patient.5
Subcutaneous and Intramuscular Routes of Administration
These routes of administration require simple diffusion from the site of injection into the systemic circulation and are dependent on blood flow to the injection site. Consequently, these administration routes can result in variations in absorption, particularly in the PACU when patients are hypothermic, hypotensive, and with any degree of peripheral vasoconstriction. Subcutaneous absorption is slow and is reserved for drugs such as insulin or hormones for which a slow, continuous absorption is advantageous. Intramuscular injections produce a more rapid action and are a common practice in the PACU. In addition, if a patient with a hypothermic condition in the PACU receives a drug either subcutaneously or intramuscularly, absorption can be delayed. However, when the patient undergoes rewarming, a significant amount of the drug can be rapidly liberated from the injection site, resulting in a large concentration of the drug in the systemic circulation with an exaggerated effect.4
Intravenous Route of Administration
This route of administration facilitates the delivery of a desired drug’s concentration in a rapid and precise manner by single-bolus injection or continuous infusion. In the PACU, because patients have an intravenous line, it is the most popular means of drug administration.
Aerosolized Medications to the Respiratory Tract
The aerosolized route of administration facilitates direct delivery from inhaled aerosols to a targeted organ, which reduces the systematic drug exposure and side effects. Many aerosol delivery devices can be used for administration of bronchoactive inhaled aerosols. The most commonly used method of administration in the PACU is the aerosolized nebulizer in which a specific amount of drug is administered in a solution of normal saline and nebulized with a ventilator or oxygen delivery device. Other devices for delivery of the drug, either orally or nasally via inhalation, are the metered dose inhaler (MDI) with or without a holding chamber or spacer device, the small volume nebulizer (SVN), and the dry powder inhaler (DPI). The MDI, SVN, and DPI devices deliver approximately the same percentage of the drug to the target organ, the lungs. The MDI allows greater patient flow rates, much better than the SVN and the DPI.5
Drug Distribution
A drug’s distribution in the body considers its availability within various defined compartments. A compartment represents a theoretic space. A mathematic model can be used to describe the pharmacokinetics of the disposition of a drug. A two-compartment model is usually used in the depiction of a central compartment and a peripheral compartment. The central compartment includes plasma, blood cells, and highly perfused tissues such as the heart, lungs, brain, liver, and kidneys. The peripheral compartment represents all other fluids and tissues in the body. With this two-compartment model, a drug can be introduced into the central compartment, move into the peripheral compartment, and then return to the central compartment where removal from the body occurs. The two-compartment model is constructed using the serum concentration versus time, and is called the plasma concentration curve. From this curve, the distribution and elimination half-times and other kinetic parameters of the drug can be calculated. A drug such as propofol will rapidly distribute into the brain when given intravenously, causing a rapid onset of sedation. It also quickly redistributes from the tissues into the blood, resulting in a short duration of action.6
Metabolism and Elimination
The major mechanisms for elimination of a drug from the body are via hepatic and renal clearance. The half-life (t½) of a drug is the time at which 50% of the total amount of the drug has been eliminated from the body. The elimination half-life (t½B) is the time that the plasma concentration is at 50% of the elimination phase; the t½B is directly proportional to the volume distribution of the drug and inversely proportional to the drug clearance. Consequently, when the t½B for a particular drug is known, a large initial dose called a loading dose of a drug can be given to achieve a therapeutic concentration. The drug can then be given via infusion or in multiple doses at calculated intervals based on the t½B for a steady-state plasma concentration. In addition, the time necessary for elimination of a particular dose of a drug can be predicted with the t½B. Usually, 95% of the drug can be eliminated in four to five half-lives.7 Many drugs are given as pro-drugs, which are inactive. These drugs require metabolism to convert the pro-drug into a pharmacologically active drug which can then produce its clinical effect.
Removal of drugs from the systemic circulation
Drugs are principally cleared from the systemic circulation via the hepatic, biliary, and renal systems. The hepatic system has a high blood flow and can extract many lipid-soluble drugs from the systemic circulation. In the liver, drugs undergo biotransformation and, for the most part, become pharmacologically inactive. Enzyme induction or a decrease in protein binding enhances the hepatic clearance of some drugs (see Chapter 16). After they have been metabolized in the liver, drugs can be transported to the biliary system or the kidney for excretion. Some drugs, such as the glucuronides, are actively transported to the bile and excreted in an inactive form.7
The kidneys secrete many water-soluble drugs in their unchanged form or as hepatic metabolites. Renal excretion of drugs depends on the following major physiologic processes that occur in the kidneys: glomerular filtration, active tubular secretion, and passive tubular reabsorption. Appropriate renal function is needed for elimination of many of the drugs administered in the perioperative period. Consequently, concern about renal function should merit an evaluation of creatinine clearance or serum creatinine levels because these laboratory tests correlate well with renal drug elimination.7
Effects of physiologic dysfunction on pharmacokinetic action
Renal Disease
Kidney disease reduces the effectiveness of drug clearance and results in a prolongation in the action of the drugs relying on the kidneys for removal. Evaluation of renal drug clearance includes creatinine clearance laboratory analysis which measures glomerular filtration (see Chapter 13). Creatinine clearance can be used to predict overall renal function and the degree of a drug’s renal clearance. In anephric patients or in patients with severe kidney disease, the elimination clearance is decreased and the t½B is increased, thus prolonging the effects of circulating medications that rely on renal clearance especially with repeated administrations.8
Hepatic Disease
Patients with hepatic diseases such as cirrhosis may have difficulty clearing some anesthetic drugs from the body. Liver function testing is unreliable for predicting the level of impairment in hepatic clearance of drugs. Any patient with documented liver disease should be considered at risk for decreased hepatic clearance of drugs. Therefore, when a patient has a documented hepatic disease, all drugs administered in the PACU should be titrated to the desired effect, using the lowest dose possible, for an appropriate pharmacologic outcome.9
Cardiovascular Disease
Cardiovascular diseases that cause a reduction in tissue perfusion have a significant effect on drug distribution and clearance. For example, when lidocaine is administered to patients with congestive heart failure, the dose should be reduced by half, because a full dose could be toxic due to changes in the volume of distribution and clearance. Patients who have undergone cardiopulmonary bypass surgery can have a hemodilution of drugs. Patients with cardiac disease should have their medications given at lower doses over longer dosing intervals with careful monitoring.10 Drugs used in the PACU are listed in Table 19.1.
Drug | Route | Onset | Peak | Duration of Action | Classification |
---|---|---|---|---|---|
Adenosine (Adenocard) | IV | < 20 s | 20–30 s | 1 min | Antiarrhythmic |
Acetaminophen (OFIRMEV) | IV | 15 min | 30 min | 6 h | Nonopioid analgesic, antipyretic |
Acetaminophen (Acephen, FeverAll) | Rectal (suppository) | 30 min | 1 h | 6 h | Nonopioid analgesic, antipyretic |
Albuterol (Proventil, Ventolin) | INH | < 5 min | 30 min–2 h | 3–6 h | Bronchodilator |
Alfentanil (Alfenta) | IV | 1–2 min | 1–2 min | 10–60 min | Opioid agonist |
Epidural | 5–15 min | 30 min | 30–60 min | ||
Aminocaproic acid (Amicar) | IV | 1–2 h | — | 8–12 h | Hemostatic agent |
Aminophylline | IV | 1–2 min | 30–60 min | 4–10 h | Bronchodilator |
PO | < 30 min | 1–5 h | 4–8 h | ||
Aprepitant (Emend) | IV | 30 | 2 h | 24 h | Antiemetic |
Atenolol (Tenormin) | IV | 5 min | 5 min | 12–24 h | Beta-adrenergic blocker |
PO | 30–60 min | 2–4 h | 24 h | ||
Atracurium (Tracrium) | IV | 2–5 min | 3–5 min | 20–35 min | Nondepolarizing NMB agent |
Atropine | IV – cardiac | 30–60 s | 1–2 min | 15–30 min | Anticholinergic |
IV – antisialagogue activity | 20–60 min | 60–90 min | 4 h | ||
IO | 1–2 min | 5–10 min | 1–2 h | ||
ETT | 10–20 s | 1–2 min | 30–45 min | ||
IM | 5–40 min | 20–60 min | 2–4 h | ||
INH | 3–5 min | 15–90 min | 3–6 h | ||
Bumetanide (Bumex) | IV | 1–5 min | 15–30 min | 4 h | Loop diuretic |
Bupivacaine (Marcaine, Exparel) | Epidural | 4–7 min | 30–45 min | 2–7 h | Local anesthetic |
InfiltrationInfiltration(liposomes) | 2–10 min4–10 min | 30–45 min2 h | 3–7 h72–96 h | ||
Spinal | < 1 min | 15 min | 2–4 h | ||
Butorphanol (Stadol) | IV | 1–2 min | 5–10 min | 3–4 h | Analgesic (agonist-antagonist combination) |
IM | 10–15 min | 30–60 min | 3–4 h | ||
Captopril (Capoten) | PO | < 15 min | 1–2 h | 2–6 h | ACE inhibitor |
Clevidipine (Cleviprex) | IV | 1–2 min | 5–10 min | 15 min | Calcium channel blocker |
Chloroprocaine (Nesacaine) | Epidural | 6–12 min | 10–20 min | 30–60 min | Local anesthetic; not to be used for spinal anesthesia |
Cimetidine (Tagamet) | IV | 30–45 min | 60–90 min | 4–5 h | Histamine receptor antagonist |
PO | 15–45 min | 1–2 h | 2–4 h | ||
Cisatracurium (Nimbex) | IV | 1–4 min | 2–7 min | 22–65 min | Nondepolarizing NMB agent |
Clonidine (Catapres) | PO | 30–60 min | 2–4 h | 6–8 h | Antihypertensive |
IV | 30–60 min | 2–4 h | 6–10 h | ||
Epidural | < 15 min | 3–4 h | |||
Cocaine HCl | Topical | < 1 min | 2–5 min | 30–120 min | Topical anesthetic; vasoconstrictor |
PO | 30–60 min | — | 2–4 h | ||
IM | 20–60 min | — | 2–3 h | Opioid agonist | |
Cyclosporine (Sandimmune) | PO | 1–6 h | 8–12 h | 1–4 d | Immunosuppressant |
Dantrolene (Dantrium, Ryanodex) | IV | < 5 min | 60 min | 3 h | Skeletal muscle relaxant; for treatment of malignant hyperthermia |
PO | 1–2 h | 4–6 h | 8–12 h | ||
Desflurane (Suprane) | INH | 1–2 min | — | Emergence in 8–9 min after discontinuation | Inhalational anesthetic agent |
Desmopressin (DDAVP) | IV | 30 min | 1.5–3 h | 8–20 h | Synthetic vasopressin analog |
Intranasal | < 60 min | 1–5 h | 8–20 h | ||
Dexmedetomidine (Precedex) | IV | 1–3 min | 5–10 min | Effects last 3–5 min after discontinuance of IV infusion | α2b-Receptor agonist sedative agent |
Dexamethasone | IV | < 8 h | 12–24 h | 36–54 h | Long-acting corticosteroid |
(Decadron) | IM | < 8 h | 1–2 h | 72 h | |
(Respihaler) | INH | < 20 min | 2–4 h | 12 h | |
(Turbinaire) | Intranasal | < 15 min | — | 12–24 h | |
Diazepam (Valium) | IV | 1–5 min | 4–8 min | 15–60 min | Benzodiazepine |
IM | 15–30 min | — | 3–6 h | ||
PO | 30–60 min | 1–2 h | 3–6 h | ||
Digoxin (Lanoxin) | IV | 5–30 min | 1–5 h | 3–4 d | Inotropic agent |
IM | 30 min | 4–6 h | 3–4 d | ||
PO | 30 min–2 h | 6–8 h | 3–4 d | ||
Diltiazem (Cardizem) | IV | 1–3 min | 2–7 min | 1–3 h | Calcium channel blocker |
PO | 30 min | 2–3 h | 4–6 h | ||
PO, extended | 1–3 h | 4–11 h | 18–24 h | ||
Diphenhydramine (Benadryl) | IV | < 3 min | 1–2 h | 3–6 h | Antihistamine |
PO | 1 h | 1–2 h | 4–6 h | ||
Dobutamine | IV | 2 min | 1–10 min | 5–10 min | Vasopressor (adrenergic agonist) |
Dolasetron (Anzemet) | IV | 5–15 min | 30–60 min | 8–12 h | Antiemetic |
Dopamine (Intropin) | IV | 2–4 min | 5 min | < 10 min | Catecholamine |
Doxapram (Dopram) | IV | 20–40 s | 1–2 min | 5–12 min | Respiratory and cerebral stimulant |
Droperidol (Inapsine) | IV, IM | 3–10 min | 30 min | 8–16 h | Tranquilizer, antiemetic |
Edrophonium (Enlon, Tensilon) | IV | 30–60 s | 1–5 min | 5–20 min | Anticholinesterase (NMB reversal agent) |
IM | 2–10 min | 5–10 min | 10–40 min | ||
Enalapril (Vasotec) | PO | 1 h | 4–6 h | 12–24 h | ACE inhibitor |
Enalaprilat (Vasotec IV) | IV | 10–15 min | 1–4 h | 6 h | ACE inhibitor |
Enoxaparin (LMW heparin) | SC | 20–60 min | 3–5 h | 12 h | Anticoagulant |
Ephedrine | IV | < 30 s | 2–5 min | 10–60 min | Sympathomimetic |
IM | 1–3 min | < 10 min | 30–60 min | ||
Epinephrine (Adrenalin) | IV | < 30 s | 2–3 min | 5–10 min | Catecholamine, sympathomimetic |
ETT | 15–30 s | 15–25 min | — | ||
INH | 1 min | 1–5 min | 1–3 h | ||
SC | 5–15 min | 20 min | — | ||
Esmolol (Brevibloc) | IV | 1–2 min | 5–6 min | 10–20 min | Cardio-selective blocker |
Ethacrynic acid (Edecrin) | IV | 5–15 min | 30 min | 2 h | Loop diuretic |
Etidocaine (Duranest) | Infiltration | 3–5 min | 5–15 min | 2–3 h | Local anesthetic |
Epidural | 5–15 min | 15–20 min | 3–5 h | ||
Etomidate (Amidate) | IV | 30–60 s | 1 min | 5–14 min | Non-barbiturate hypnotic |
Famotidine (Pepcid) | IV | < 30 min | 30 min | 8–12 h | H2 antagonist |
PO | 20–45 min | 1–3 h | 8–12 h | ||
Fenoldopam (Corlopam) | IV (continuous infusion) | 5 min | 15 min | Rapidly metabolized after discontinued | Antihypertensive |
Fentanyl (Sublimaze) | IV | < 30 s | 3–7 min | 30–60 min | Opioid agonist |
Epidural, spinal | 4–10 min | < 30 min | 3–8 h | ||
IM | < 8 min | 20–30 min | 1–2 h | ||
Transdermal | 12–18 h | 1–3 d | 3 d | ||
Flumazenil (Romazicon) | IV | 1–2 min | 6–10 min | 45–90 min | Benzodiazepine-receptor antagonist |
Furosemide (Lasix) | IV | 2–5 min | 20–30 min | 2 h | Loop diuretic |
PO | 30–60 min | 1–2 h | 4–8 h | ||
Glucagon | IV, IM | 5 min | 2–20 min | 10–30 min | Antihypoglycemic |
Glipizide (Glucotrol) | PO | 60–90 min | 2–3 h | 10–24 h | Hypoglycemic |
Glycopyrrolate (Robinul) | IV – Cardiac | 1–3 min | 3–5 min | 2–3 h | Anticholinergic |
IV – antisialagogue activity | 15–20 min | 30–45 min | 2–7 h | ||
IM | 15–30 min | 30–45 min | 2–7 h | ||
Granisetron (Kytril) | IV | 2–4 min | 5–8 min | 24 h | Serotonin receptor antagonist |
Haloperidol (Haldol) | IV | 5–30 min | 1 h | 6–8 h | Long-acting tranquilizer |
Heparin (Liquaemin, Pan heparin) | IV | Immediate | Dose dependent | Dose dependent | Anticoagulant |
SC | 20–30 min | 2–4 h | 12–16 h | ||
Hetastarch (Hespan) | IV | 15–30 min | 1 h | 24–48 h | Plasma expander |
Hyaluronidase (Wydase) | SC | Immediate | — | 30–60 min | Enzyme to increase absorption |
Hydralazine (Apresoline) | IV | 5–20 min | 10–60 min | 2–4 h | Direct-acting arterial vasodilator |
IM | 10–30 min | 30–80 min | 2–8 h | ||
PO | 30–120 min | 2 h | 2–8 h | ||
Hydrocortisone sodium succinate (Solu-Cortef) | IV, IM | 5 min | — | 30–36 h | Corticosteroid |
Hydromorphone (Dilaudid) | IV | < 60 s | 5–20 min | 2–4 h | Opioid (mixed) |
IM, PO | 15–30 min | 30–60 min | 4–6 h | ||
Ibutilide fumarate (Covert) | IV | Immediate | 10 min | 10–30 min | Antiarrhythmic |
Insulin, Lente | SC | 1–4 h | 7–15 h | 18–26 h | Antidiabetic agent |
Insulin, NPH | SC | 1–2 h | 4–12 h | 18–26 h | |
Insulin, Regular | SC | 30–60 min | 1–5 h | 5–8 h | |
Insulin, Semilente | SC | 1–3 h | 4–10 h | 12–16 h | |
Insulin, Ultralente | SC | 4–8 h | 14–24 h | 28–36 h | |
Insulin, NPH 70/Regular 30 | SC | 30 min | 2–12 h | 24 h | |
Ipratropium (Atrovent, Itrop) | INH | 15–30 min | 1–2 h | 4–5 h | Anticholinergic for reactive airways disease |
Isoflurane (Forane) | INH | 1–2 min | — | Emergence in 10-15 min after discontinuation | Inhalational anesthetic agent |
Isoproterenol (Isuprel) | IV | Immediate | 1 min | 1–5 min | Sympathomimetic |
Ketamine (Ketalar) | IV | 30–60 s | 1 min | 5–15 min | Dissociative anesthetic |
IM | 3–4 min | 5–8 min | 12–25 min | ||
Ketorolac (Toradol) | IV | < 1 min | 30 min | 4–6 h | Nonsteroidal anti-inflammatory |
IM | < 10 min | 45–60 min | 4–6 h | ||
PO | 30–60 min | 1–3 h | 3–7 h | ||
Labetalol (Normodyne, Trandate) | IV | 1–3 min | 5–15 min | 15 min–2 h | Adrenergic antagonist |
PO | 20–40 min | 1–4 h | 4–12 h | ||
Lansoprazole (Prevacid) | PO | 1 h | 2 h | > 24 h | Proton pump inhibitor |
Lidocaine (Xylocaine) | IV | 45–90 s | 1–2 min | 10–20 min | Local anesthetic |
Epidural | 5–15 min | 20–30 min | 60–120 min | ||
Infiltration | < 60 s | 20–30 min | 30–120 min | ||
Spinal | < 60 s | < 10 min | 60–90 min | ||
Lorazepam (Ativan) | IV | 1–5 min | 20–40 min | 4–6 h | Benzodiazepine |
PO | 20–30 min | 2 h | 10–20 h | ||
Magnesium sulfate | IV | Immediate | 2–3 min | 30 min | Anticonvulsant |
Mannitol (Osmitrol) | IV, diuresis | 15–60 min | 1–3 h | 3–8 h | Osmotic diuretic |
Epidural | < 15 min | 60 min | 3–8 h | ||
IV, IOP | 30–60 min | 1–2 h | 4–6 h | ||
Meperidine (Demerol) | IV | 1–3 min | 5–20 min | 2–4 h | Synthetic opioid agonist |
IM | 5–10 min | 30–50 min | 2–4 h | ||
PO | 10–45 min | 60 min | 2–4 h | ||
Mepivacaine (Carbocaine) | Epidural | 5–15 min | 15–45 min | 3–5 h | Local anesthetic |
Infiltration | 3–5 min | 15–45 min | 45–90 min | ||
Metaproterenol (Metaprel) | INH | < 60 s | 60 min | 1–4 min | Bronchodilator |
Methadone (Dolophine) | IV | 1–3 min | 15 min | 6 h | Synthetic opioid |
IM | 3–60 min | 30–60 min | 6 h | ||
PO | 30–60 min | 45 min | 6 h | ||
Methohexital (Brevital) | IV | < 30 s | 30–120 s | 5–10 min | Ultra–short-acting barbiturate |
Rectal | 5–7 min | 5–10 min | 45–90 min | ||
Methylene blue (Urolene Blue) | IV | < 1 min | < 1 h | Varies | Antidote for methemoglobinemia |
Methylergonovine (Methergine) | IV | Immediate | 5–10 min | 45 min | Oxytocic |
IM | 2–5 min | 30 min | 3 h | ||
Metoclopramide (Reglan) | IV | 1–3 min | 30–60 min | 1–2 h | Prokinetic agent, dopamine-receptor antagonist, antiemetic |
IM | 10–15 min | 30–60 min | 1–2 h | ||
PO | 30–60 min | 1–2 h | 1–2 h | ||
Metoprolol (Toprol) | IV | < 5 min | 20 min | 5–8 h | Beta-adrenergic blocker |
PO | < 15 min | 90 min | 12–19 h | ||
Midazolam (Versed) | IV | 1–5 min | 2–5 min | 15–90 min | Benzodiazepine |
IM | 10–15 min | 30–60 min | 1–3 h | ||
PO | 10–15 min | 30–60 min | 2–6 h | ||
Milrinone (Primacor) | IV | 2 min | 15 min | 2 h | Inotropic agent |
Morphine | IV | < 1 min | 20 min | 2–7 h | Opioid agonist |
Morphine (Duramorph) | Epidural | 60 min | 90 min | 6–18 h | Opioid agonist |
IM | 1–5 min | 30–60 min | 3–7 h | ||
PO | 15–60 min | 30–60 min | 3–7 h | ||
PO, extended | 60–90 min | 1–4 h | 6–12 h | ||
Spinal | < 60 min | 1–2 h | 12–24 h | ||
Nalmefene HCl (Revex) | IV | 2 min | 5 min | 4–6 h | Opioid antagonist |
IV | 2–3 min | 15–30 min | 3–6 h | ||
IM | 15 min | 30–60 min | 3–6 h | ||
Naloxone (Narcan) | IV | 1–2 min | 5–15 min | 1–4 h | Opioid antagonist |
IM | 2–5 min | 5–15 min | 1–4 h | ||
Naltrexone (ReVia) | PO | 5 min | 1 h | 24–72 h | Opioid antagonist |
Neostigmine (Prostigmin) | IV | < 3 min | 7 min | 45–60 min | Anticholinesterase (NMB reversal agent) |
Nicardipine (Cardene) | IV | 1 min | 15 min | 3 h | Calcium channel blocker |
PO | < 30 min | 30–60 min | 3 h | ||
Nifedipine (Procardia) | PO | 15–20 min | 30–120 min | 4–12 h | Calcium channel blocker |
PO, extended | 20–30 min | 6 h | 24 h | ||
SL | 5 min | 20–45 min | 4–12 h | ||
Nitroglycerin | IV | 1–2 min | 1–5 min | 3–5 min | Antihypertensive, nitrate vasodilator |
Ointment | 20–60 min | 3–6 h | — | ||
SL | 1–3 min | 30–60 min | — | ||
Transdermal | 40–60 min | 18–24 h | — | ||
Nitroprusside (Nipride) | IV | 30–60 s | — | 1–10 min | Peripheral vasodilator |
Nitrous oxide (N2O) | INH | 1–5 min | — | 5–10 min after discontinued | Inhalational anesthetic agent |
Nizatidine (Axid) | PO | 30–60 min | 30 min–3 h | 8–12 h | H2-receptor antagonist |
Norepinephrine (Levophed) | IV | < 60 s | 1–2 min | 2–10 min | Catecholamine, sympathomimetic |
Omeprazole (Prilosec) | PO | 1 h | 2 h | 72 h | Proton pump inhibitor |
Ondansetron (Zofran) | IV | < 30 min | 1–1.5 h | 12–24 h | Serotonin (5-HT3) receptor antagonist |
Oxazepam (Serax) | PO | 30 min | 2 h | 8–12 h | Benzodiazepine |
Oxytocin (Pitocin) | IV | < 30 s | 20–40 min | 60 min | Oxytocic |
IM | 3–5 min | 40 min | 2–3 h | ||
Palonosetron (Aloxi) | IV | 5–15 min | 2–4 h | 24–72 h | Antiemetic |
Pancuronium (Pavulon) | IV | 1–3 min | 3–5 min | 40–90 min | Nondepolarizing NMB agent |
Phentolamine (Regitine) | IV | 1–2 min | — | 10–15 min | Alpha-adrenergic blocker |
IM | 5–20 min | — | 30–45 min | ||
Pentobarbital (Nembutal) | IV | Immediate | 1–2 min | 15 min | Barbiturate |
Phenylephrine (Neo-Synephrine) | IV | < 30 s | 1 min | 15–20 min | Alpha-adrenergic agonist |
Phenytoin (Dilantin) | IV | 3–5 min | 1–2 h | 22 h | Anticonvulsant |
Physostigmine (Antilirium) | IV | 3–8 min | 5–10 min | 30 min–5 h | Anticholinesterase (NMB reversal agent) |
Prilocaine (Citanest) | SC | 1–2 min | < 30 min | 30 min–1.5 h | Local anesthetic |
Epidural | 5–15 min | < 30 min | 1–3 h | ||
Procainamide (Pronestyl) | IV | Immediate | 5–15 min | 2.5–5 h | Antiarrhythmic |
Procaine (Novocain) | SC | 2–5 min | < 30 min | 15–30 min | Local anesthetic |
Spinal | 2–5 min | < 30 min | 30 min–1.5 h | ||
Epidural | 5–25 min | < 30 min | 30 min–1.5 h | ||
Prochlorperazine (Compazine) | IV | 3–5 min | 15–30 min | 3–4 h | Antiemetic, antipsychotic |
IM | 10–20 min | 15–30 min | 3–4 h | ||
PO | 30–40 min | 2–4 h | 3–4 h | ||
Rectal | 60 min | 3–4 h | — | ||
Promethazine (Phenergan) | IV | 3–5 min | 1–2 h | 2–8 h | Phenothiazine, H1-receptor antagonist |
IM | 20 min | 1–2 h | 2–8 h | ||
Propofol (Diprivan) | IV | 30–60 s | 1 min | 5–20 min | Nonbarbiturate anesthesia induction agent |
Propranolol (Inderal) | IV | < 2 min | 1 min | 1–6 h | Beta-adrenergic receptor antagonist |
PO | 30 min | 60–90 min | 8–12 h | ||
Protamine sulfate | IV | 30–60 s | < 5 min | 2 h | Heparin antagonist |
Ranitidine (Zantac) | IV | < 15 min | 1–2 h | 6–8 h | H2-receptor antagonist |
PO | < 30 min | 2–3 h | 8–12 h | ||
Remifentanil (Ultiva) | IV | 1–5 min | — | Opiate effect ceases 18 min after discontinued | Opioid |
Rocuronium (Zemuron) | IV | 45–90 s | 1–3 min | 30–120 min | Nondepolarizing NMB agent |
Ropivacaine HCl (Naropin) | SC | 1–5 min | — | 2–6 h | Local anesthetic |
Epidural | 5–13 min | — | 3–5 h | ||
Salmeterol (Serevent) | INH | 10–20 min | 30 min | 12 h | Long-acting beta-adrenergic agonist (LABA) |
Scopolamine (Transderm-Scop) | IV | Immediate | — | 30–60 min | Anticholinergic |
IM | 30 min | — | 4–6 h | ||
Transdermal | 4 h | — | 72 h | ||
Sevoflurane (Ultane) | INH | 1–2 min | — | Emergence in 9–12 min after discontinuation | Inhalational anesthetic agent |
Sodium citrate (Bicitra) | PO | 2–10 min | 60 min | 60–90 min | Nonparticulate neutralizing buffer |
Somatostatin (Zecnil) | IV | 5–10 min | 45 min | 1 h | Synthetic somatostatin |
Sotalol HCl (Betapace) | PO | 1 h | 2.5–4 h | 4–6 h | Antiarrhythmic |
Sodium bicarbonate | IV | 2–10 min | 10–30 min | 30–60 min | Neutralizing buffer |
Sodium citrate | PO | < 60 s | 3–4 min | 2 h | Neutralizing buffer |
Sodium nitroprusside | IV | 30–60 s | 1–2 min | 1–10 min | Antihypertensive, nitrate vasodilator |
Succinylcholine (Anectine, Quelicin) | IV | 30–60 s | 1 min | 4–6 min | Depolarizing NMB agent |
IM | 2–3 min | 10–30 min | — | ||
Sufentanil (Sufenta) | IV | 1–3 min | 3–5 min | 20–45 min | Opioid agonist |
Epidural, spinal | 4–10 min | < 30 min | 2–4 h | ||
Sugammadex | IV | 1–3 min | 15–25 min | 2 h | Cyclodextrin (NMB reversal agent) |
Terbutaline (Brethine) | INH | 5–30 min | 1–2 h | 3–4 h | Beta-adrenergic agonist |
PO | 30 min | 2–3 h | 4–8 h | ||
SC | 15 min | 30–60 min | 1.5–4 h | ||
Tetracaine (Pontocaine) | Spinal | < 10 min | 15–60 min | 1.25–3 h | Local anesthetic |
Torsemide (Demadex, Presaril) | IV | 10 min | 1–2 h | 6–8 h | Loop diuretic |
Vancomycin (Vancocin) | IV | 15–30 min | 4–6 h | 8–12 h | Antimicrobial agent |
Vasopressin (Pitressin) | IV | 15–30 min | 30–60 min | 2–8 h | Antidiuretic hormone, vasopressor agent |
Vecuronium (Norcuron) | IV | 2–3 min | 3–5 min | 25–40 min | Nondepolarizing NMB agent |
Verapamil (Isoptin) | IV | 2–5 min | < 10 min | 30–60 min | Calcium channel blocker |
PO | 30 min | 1–2 h | 3–7 h | ||
Vitamin K (Aquamephyton) | IM, IV, SC | 1–3 h | — | 6–48 h | Water-soluble vitamin |
Warfarin (Coumadin) | PO | Up to 5–7 d | — | 2–5 d after therapeutic dose reached | Anticoagulant |
ACE, Angiotensin-converting enzyme; DDAVP, 1-deamino-8-d-arginine vasopressin; ET, endotracheal tube; IM, intramuscular; INH, inhalation; IO, intraosseous; IOP, intraocular pressure; IV, intravenous; NMB, neuromuscular blocker; NPH, neutral protamine Hagedorn; PO, by mouth; SC, subcutaneous; SL, sublingual.
Adapted from Nagelhout JJ, Plaus KL. Handbook of nurse anesthesia. 5th ed. St. Louis, MO: Saunders; 2014.
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