Surgical pharmacology

Surgical pharmacology

Key terms and definitions

Sealed glass tube containing a drug. Tip is scored for removal by snapping off. Drug is removed by a sterile syringe and filter needle to prevent aspiration of glass shards.

One drug is used to alter or stop the effect of another drug.

Standard scale of equivalents used to measure between metric, English, and apothecary.

Diagnostic chemical

Used to perform a medical test or confirm a pathogenic condition.

Colored solution used to identify structures with gross vision.

Chemical used in solution to tint cellular structures for microscopic study.

Contrast medium

Radiopaque solution used during radiography or fluoroscopy to define structures on film or digital media.

Liquid used to decrease the concentration of a substance.

A nonsolid, nonliquid form of a chemical.

Chemically equivalent drugs formulated as substitutes for brand-name products.

Below the skin.

Flow of a drug directly into the circulatory system.

Drug that is taken in like a breath, and then absorbed through the respiratory tract.

Insertion of a drug directly into the tissues using a syringe and needle.

Loading dose

The first dose of a series given in a larger quantity than the subsequent doses.

Localized drug effect

The physiologic response to a drug is in a select area of the body and not carried to other regions in an effective form.³

Pharmacokinetics

The actions and disposition of a chemical in the body.

The drug is taken in by the cells of the body.

Distribution

The drug is evenly absorbed by the entire body.

The drug is used throughout the body and broken down by major organs.

The drug is released from the body in naturally excreted substances.

An inert substance given to a patient to stimulate the power of suggestion of effectiveness. Commonly used as a control in experimental medicine.

Polypharmacy

A term used to describe when a patient has multiple prescription medications from one or multiple prescribers.

Potentiation

A synergistic action of one drug against another to cause an increased response by the body.

Preventive drug

Chemical or biologic preparation given with the intent of avoiding a disease state.

Reaction to a drug

The physiologic response of the body when exposed to a drug. The response can be positive or negative.

Sensitivity

Physiologic mechanisms are triggered by exposure to small doses of a given drug.

Physiologic defense mechanisms are triggered by exposure to a drug or chemical, causing a potentially life-threatening response.

Anaphylaxis

Severe physiologic response to exposure to a drug or chemical, causing a definite threat to the patient’s life.

Receptor site

Location in the body that acts in response to a chemical stimulus. Some drugs act by blocking a receptor site and prevent naturally produced chemicals from bonding.

Side effect

A secondary reaction that occurs in response to administration of a drug.

Systemic drug effect

The physiologic response to a drug is manifest in the entire body.

The physiologic response caused by prolonged use of large quantities of a drug that makes average doses ineffective.

A level of any given drug that causes a negative or possibly fatal physiologic response.

A vacuum-sealed glass or plastic container of medication that is sealed by a rubber stopper. The drug is removed by a sterile syringe and needle.

Website

Http://evolve.elsevier.com/berrykohn

• Historical Perspective

• Self-Assessment Activities

Pharmacology baselines

The main purpose of this chapter is to highlight information concerning the drugs specifically used in perioperative patient care. This chapter is not intended to be an all-inclusive pharmacologic resource. Drugs used in diagnostics, surgical procedures, anesthesia, and emergencies in the OR are described in more depth in the corresponding subsequent chapters. Drugs used in patient care areas other than the perioperative environment can be reviewed at www.globalrph.com/druglist.htm. This site has most of the common drugs and dosages listed in chart form.

Many drugs and pharmaceutical substances require special preparation and handling in the surgical environment. Some of these pharmaceuticals are found only in the OR, and their proper use is based on sterile technique, precise actions, and extreme caution. Correct dosing, mixing, and delivery to the sterile field are important for the safety of the patient and the team.

Safe drug and pharmaceutical administration in the OR is practiced according to the seven rights of medication administration in any setting:

• Right patient

• Right route

• Right reason

• Right documentation

Patient assessment will provide information about the patient’s health and general condition. Knowledge of how a drug acts in the body should be compared with the patient’s assessment and current vital sign trend. The patient’s weight should be documented in kilograms because many dosages are calculated according to the milligrams per kilograms. The patient’s history or body size may require a change in the plan of care involving medications for the intraoperative care period. Allergies are assessed and documented, and reactions are prevented.

Prescription items in the OR are more than drugs and medications. The effectiveness of surgical drugs and chemicals is dependent on the desired localized drug effect and the specific targeted receptor sites. Some drugs are used to decrease consciousness; others are used to alleviate pain. Many cause amnesia. The physiologic drugs are given in larger loading doses to induce the desired effect and titrated to maintenance doses to keep the patient’s body relaxed and pain-free during the surgical procedure.

Surgical pharmacology encompasses many chemicals ranging from dyes to adhesives, most of which are not used in any other patient care area. All of the specialized items require special handling within the confines of the sterile field. Other items used in the OR include gaseous materials and surgical-site closure materials.

Avoiding pharmaceutical error

Every patient population is at risk for errors during the use of pharmaceutical materials in the perioperative environment. Known and unknown allergies and sensitivities can lead to serious illness or death. Constant patient monitoring can identify signs and symptoms of evolving reactions and permit time to effect treatment. Always investigate complaints of patients when they report unusual feelings when a drug has been given.

Dosage error can affect any patient, but pediatric, geriatric, or patients with impaired body systems are particularly at risk. Pediatric error is usually related to doses greater than their bodies can tolerate. Geriatric and system-impaired patients metabolize medications at a slower rate. Any drug in their systems can be augmented by additional drugs in a subsequent dose. The end result can be unintentional overdosage. Pharmaceuticals most frequently identified as problems are anticoagulants, antibiotics, and steroidal compounds.

Key points in avoiding error include double-checking labels for drug, dose, and method of delivery. The patient should be identified at least twice by name and other identifier approved by facility policy. Allergy and sensitivity alerts should be clear in the record and on the patient’s identification wristband.

The risk of pharmaceutical error is high when patients take prescribed or unprescribed medications at home. A patient may use an inhaler for asthma and forget to report its use before surgery. Dietary supplements, herbs, home remedies, and over-the-counter (OTC) drugs are not considered “medication” to the patients, and they may neglect to report their use.

Some patients may hide the fact that they are using additional materials at home for fear of angering the physician. Patients using recreational drugs may hide the fact for fear of punishment. Most facilities do not routinely test for illegal drugs unless prompted by the situation or by a patient who acts suspicious when queried concerning their use. Not only does the use of drugs (legal and illegal) and supplements alter the course of treatment, but they can potentially interact adversely with many forms of anesthesia and physiologic stabilization drugs during surgery or emergency treatment.

Pregnancy classifications and lactation considerations

The safe administration of any drug to a pregnant woman requires knowledge of how the drug might affect a developing fetus and the mother’s physiology, such as cardiac output and renal arterial blood flow.

All drugs, chemicals, and solutions in surgery have a pregnancy classification, including solutions such as bacteriostatic water, which has a pregnancy classification of “C.” Large amounts of preservative with bacteriostatic properties might accumulate in quantities sufficient to harm a developing fetus or cause the mother’s kidneys to fail. The risks should be identified before any drug is administered to a pregnant or possibly pregnant woman. Pregnancy classifications from the Food and Drug Administration (FDA) are as follows:

A No known risk during first trimester and no evidence in later trimesters

B No risk shown in animals, but no studies on pregnant women

C Possible risk found in studies in animals. No studies on pregnant women

D Positive risk found in human fetus

X Fetal anomalies found. Contraindicated for pregnant or possibly pregnant women

A breastfeeding mother and her infant are at risk if a drug given is transferred by breast milk. Antidepressants, antihypertensives, narcotics, cardiac, salicylates, psychotropics, some anesthetics, and anticholesterol drugs are examples of some drugs passed in breast milk that can have an effect on the infant. A mother can be advised to pump and store milk preoperatively if a potentially harmful drug will be used in her procedure. The physician will advise when it is safe to resume regular breastfeeding. The mother should be instructed what to observe for in her infant after feeding.

Drug development

New drugs take many years to become available for patient use. According to the Office of Research and Development of the Pharmaceutical Manufacturers Association, it takes almost 12 years for a drug to be discovered and placed into use. Safety and efficacy testing on animals and laboratory simulation takes an average of 3½ years to complete. It is estimated that only 1 of every 1000 compounds is actually tested in human trials. Each potential drug is filed with the U.S. Food and Drug Administration (FDA) in an Investigational New Drug (IND) application. A series of clinical trials are performed on humans, who have given informed consent as follows:

• Phase I clinical trial: 20 to 80 healthy individuals for a period of 1 year. The drug is studied for safety in dosage, duration of action, absorption, distribution, metabolism, and excretion.

• Phase II clinical trial: 100 to 300 people with actual disease process for which the drug is proposed treatment for a period of 2 years. The drug is studied for effectiveness and tolerability. Adverse reactions are monitored.

• Phase III clinical trial: 1000 to 3000 patients in multiple health care settings participate. The drug is monitored to validate effectiveness and safety.

• Phase VI postmarket surveillance: After the drug is on the market, the manufacturer monitors the users for therapeutic and nontherapeutic effects and reports to the FDA.

Clinical trial results are reported yearly to the FDA. Only one in five drugs ever completes the three-clinical-trial process. The long period needed for the clinical trials permits the researchers to observe for long-term effects of the compound. Upon completion of the clinical trial phases, the drug manufacturer submits a New Drug Application (NDA). Once approved by the FDA, the new drug is made available for physicians to prescribe. The approval process takes between 6 and 29 months to complete.

Drug names

Drugs have three names. The first name, which is the chemical name, describes the chemical components such as molecular and atomic structure of the drug. It is not commonly used when referencing the drug.

The second name is the official name, referred to as generic, and given to the compound by the initial manufacturer. The generic name is derived from the chemical name and is not capitalized. The drugs are listed in the United States Pharmacopeia (USP) and the National Formulary (NF) according to the generic names.

For the third name, the drug company who is selling the drug will assign a copyrighted trade name, or a brand name, which is proprietary. The trade name is capitalized and designated by a registration mark (®).

Mathematics baselines

Decimals

Numbers to the left of the decimal are whole numbers. Numbers to the right of the decimal are decimal fractions and are read according to their place value:

one ten thousandth

Addition of decimals

1. Write numbers in a column with the decimals vertically aligned.

2. Place the decimal in the answer beneath the decimal in the problem.

Example: Add 1.33, 4.0, 2.146, and 0.03

1.334.02.146+ 0.03 7.506

Subtraction of decimals

1. Write numbers in column with the decimals vertically aligned.

2. Subtract and place the decimal in the answer beneath the decimal in the problem.

Example: Subtract 0.025 from 15.838

15.838− 0.02515.813

Multiplication of decimals

1. Find the product of the numbers.

2. Total the number of decimal places in the multiplicand and in the multiplier.

3. Mark off the total decimal places in the product, and insert a decimal.

Example: Multiply 2.05 by 0.2

2.05 (multiplicand)× 0.2 (multiplier)=0.410 (product with three decimal places marked off )

When the number of decimal places to be marked off goes beyond the numbers in the product, add a zero in each place.

To multiply a decimal by 100, 1000, or 10,000, move the decimal to the right as many places as there are zeros in the multiplier.

Example: Multiply 0.25 by 100. There are two zeros, so move the decimal two places to the right: 025., or 25.

To multiply a decimal by 0.1, 0.01, 0.001, move the decimal to the left as many places as there are decimal places in the multiplier.

Example: Multiply 0.25 by 0.1. There is one decimal place, so move the decimal one place to the left: 0.025.

If the decimal must be moved farther than there are numbers, add a zero for each decimal place.

Division of decimals.

To divide a decimal by a whole number:

1. Write the problem.

2. Place a decimal in the quotient directly above the decimal in the dividend.

3. Solve the quotient.

Example: Divide 0.1 by 50

(divisor)500.0020.100(dividend)

To divide a whole number or decimal by a decimal:

1. Move the decimal in the divisor to the right until the divisor is a whole number.

2. Move the decimal in the dividend to the right as many places as you moved the decimal in the divisor.

3. Place the decimal in the quotient directly above the (moved) decimal in the dividend.

4. Solve the quotient.

Example: Divide 0.225 by 0.5

To divide a decimal by 10, 100, 1000, and so on, move the decimal to the left as many places as there are zeros in the divisor.

Example: Divide 0.25 by 1000. There are three zeros, so move the decimal three places to the left: 0.00025.

To divide a decimal by 0.1, 0.01, 0.001, and so on, move the decimal to the right as many places as there are decimal places in the divisor.

Example: Divide 0.25 by 0.1. There is one decimal place, so move the decimal one place to the right: 02.5, or 2.5.

Percent

The word percent means part of 100. Twenty-five percent (25%) means 25 parts of 100, or 25/100; also written as the decimal 0.25. Percent indicates a fraction in which the denominator is 100.

Fractions

A fraction represents a part of a whole number. If a circle is divided into four equal parts, each part is ¼ of the circle, as seen in Figure 23-1. The numerator is 1 and the denominator is 4. The line between 1 and 4 means divide.

FIG. 23-1 Parts of the whole (fractions).

Common denominator.

Unlike denominators cannot be added or subtracted. Common denominator means the fractions have the same denominator.

Reduce a fraction to lowest terms.

Determine the largest number that divides evenly into both numbers; when the fraction cannot be reduced any further, it is in its lowest terms.

Example: Reduce to lowest terms: 20/80

Both numbers are divisible evenly by 20: 20 × 20 × 1, and 80 × 20 × 4

Therefore the lowest terms of 20/80 are ¼.

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Apr 6, 2017 | Posted by admin in GENERAL SURGERY | Comments Off

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