Basic Principles of Pharmacology

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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).


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.

Table 19.1

Drugs Used in the Postanesthesia Care Unit: Perianesthesia Drug List
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


2–10 min

4–10 min
30–45 min

2 h
3–7 h

72–96 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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May 20, 2023 | Posted by in NURSING | Comments Off on Basic Principles of Pharmacology

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