Pharmacology of Valacyclovir and Crystalloids

Exam 3 Study Guide

• Exam 3 covers material from Weeks 5 through 8
• Thoroughly review Sherpath lessons from Weeks 5-8, EAQs, and PowerPoint slides.
• The exam consists of 45 questions totaling 82 points.
• Some questions may have multiple parts.
• Review all OSMOSIS videos for medications.

Mechanism of Action of Valacyclovir

• Valacyclovir is an antiviral prodrug metabolized to acyclovir in the body.
• Acyclovir is a synthetic nucleoside analogue that inhibits viral DNA polymerase, preventing herpes simplex virus replication.
• Acyclovir mimics a natural building block of viral DNA, integrating into the growing viral DNA chain, causing premature termination and halting viral replication.
• Valacyclovir offers higher oral bioavailability than acyclovir, allowing for less frequent dosing.
• The active metabolite acyclovir is responsible for the antiviral activity against HSV and VZV.

Side Effects of Valacyclovir

• Potential side effects include headache and nausea.
• More serious side effects include nephrotoxicity, thrombotic thrombocytopenic purpura, and hemolytic uremic syndrome.
• Valacyclovir should be used cautiously with electrolyte imbalance or dehydration.
• Combined use with zidovudine increases zidovudine levels and neurologic side effects.
• Combined use with aminoglycosides increases nephrotoxicity risk.
• Valacyclovir can cause neurological side effects, including agitation, tremors, confusion, and myoclonus.
• Hallucinations and encephalopathy/seizures are also possible.

Safe IV Insertion Sites

• The most common and safe sites for IV insertion are the veins on the inner aspect of the forearm.
• The antecubital fossa (front of the elbow), back of the hand, and foot veins in children are also safe.
• Avoid using hand veins in older adults or ambulatory patients due to increased risk of complications.
• Avoid areas with signs of infection, infiltration, thrombosis, vascular grafts/fistulas, or on the same side as a mastectomy.
• Avoid visible veins on the chest, breast, abdomen, or trunk.
• Proper site selection, vein assessment, and technique are crucial for successful IV insertion and preventing complications.
• Vascular visualization technology can aid in locating suitable veins for patients with difficult IV access.

Safe IV Insertion Considerations

• Avoid the fragile dorsal veins of the older adult client. These veins have a greater risk for tissue damage and developing an infiltration or thrombophlebitis.
• Avoid areas of joint flexion (e.g., wrist, antecubital fossa).
• Avoid areas with pain on palpation.
• Avoid sites distal to previous venipuncture site, sites with sclerosed or hardened veins, previous infiltrations or extravasations, areas of venous valves, or phlebitic vessels.
• Avoid compromised skin and distal sites to these areas (e.g., areas with open wounds, extremities with infection).
• Avoid locations that interfere with planned procedures.
• Avoid veins compromised by breast surgery, axillary node dissection, lymphedema or after radiation, arteriovenous (AV) fistulas/grafts, or affected extremity from cerebrovascular accident (CVA).
• Choose site that will not interfere with patient's activities of daily living (ADLs), use of assist devices, or planned procedures.

Clinical Findings of Cellulitis

• Localized area of erythema (redness) and edema (swelling).
• Warmth and tenderness over the affected area.
• Spreading redness with indistinct borders.
• Possible drainage or oozing if skin is broken.
• Fever and chills may be present if systemic infection.
• Lymphangitis (red streaks tracking along lymph vessels) and lymphadenopathy (swollen lymph nodes).

Treatment for Cellulitis

• Discontinue the infusion and remove the catheter.
• Elevate the extremity.
• Apply warm compresses 3-4 times/day.
• Obtain a specimen for culture at the site and prepare the catheter for culture if drainage is present.
• Administer antibiotics, analgesics, and antipyretics.
• Rotate sites at least every 72 hours.
• Avoid inserting an IV into the lower extremities.
• Use hand hygiene and surgical aseptic technique.

IV Complications

• Infiltration, Phlebitis, Cellulitis, Extravasation, Overload, Air Embolus, Inflammation of loose connective tissue around insertion site.
• Caused by poor aseptic insertion technique.
• Treated with antibiotics.
• Red swollen area spreads from insertion site outwardly in a diffuse circular pattern.

Reasons for IV Med Administration

• Maintain or restore fluid volume and electrolyte balance.
• Nourish a patient with calories.
• Provide needed medication (routine or emergent) to a patient.
• Administer blood products.
• Provide avenue for diagnostic lab testing.

Antidotes for Drugs Reviewed in Class

• Naloxone - Reverses effects of opioid overdose by blocking opioid receptors.
• Flumazenil - Reverses effects of benzodiazepine overdose by blocking benzodiazepine receptors.
• N-acetylcysteine - Antidote for acetaminophen overdose, prevents formation of toxic metabolites.
• Fomepizole - Antidote for toxic alcohol poisoning like methanol and ethylene glycol.
• Digoxin immune Fab - Binds and neutralizes digoxin in digoxin toxicity.
• Deferoxamine - Chelating agent used for iron poisoning and iron overload.
• Hydroxocobalamin - Binds cyanide and used as an antidote for cyanide poisoning.
• Protamine sulfate - Reverses effects of heparin by binding to it.

Hypotonic IV Fluids

• Hypotonic IV fluids have a lower osmolarity than normal body fluids.
• When infused, fluid shifts from the vascular space into cells.
• This results in cellular swelling and a decrease in plasma volume.
• Such fluids are used carefully in clinical settings.
• Proper monitoring of fluid balance is crucial.

Potassium Replacement

• Verify provider order for dose, concentration, and rate (double check calculations).
• Assess patient's kidney function and urine output.
• Never give potassium as an IV push or bolus due to risk of cardiac dysrhythmias.
• Administer potassium via infusion pump or buretrol for controlled rate (do not exceed 10 mEq/hr for non-monitored patients or 20 mEq/hr for monitored patients).
• Monitor patient on cardiac monitor throughout infusion, and watch for ECG changes.
• Assess patient for signs of hyperkalemia like muscle weakness, paresthesias, or arrhythmias.
• Provide thorough patient education regarding potassium's role, dietary sources, and importance of compliance.
• Document potassium level, dose given, route, rate, patient response, and any adverse effects.
• Ensure careful dosing, administration technique, and monitoring are crucial.

Crystalloid Solutions Adverse Effects

• Edema (fluid buildup) anywhere in the body, including peripheral edema and pulmonary edema.
• Dilution of plasma proteins reduces colloid oncotic pressure, leading to fluid within blood vessels.
• Fluid overload if large volumes are infused over a prolonged period.
• Short-lived effects requiring repeated administration of large volumes.
• Careful monitoring of fluid status is crucial for mitigating potential adverse effects of crystalloid solutions.

Patient Cues to Decrease IV Therapy

• Improvement in the condition requiring IV fluids or medications, such as stabilized vitals or resolution of dehydration.
• Development of complications from IV therapy (phlebitis, infiltration, or fluid overload).
• Ability to tolerate oral intake, transitioning to oral medications.
• Discharge orders or transfer to a lower level of care where IV access is no longer required.
• Patient request or refusal to continue IV therapy after education on risks/benefits.
• Continuous assessment of the patient's response and ongoing need for IV therapy.

Treatment for Genital Herpes

• Antiviral medications (acyclovir, valacyclovir, and famciclovir) are recommended.
• These medications can be taken episodically at the first sign of an outbreak to reduce severity and duration; or for suppressive daily therapy to prevent outbreaks.
• Intravenous acyclovir may be used for severe cases.

Acyclovir

• Acyclovir is a synthetic purine nucleoside analog and is the drug of choice for herpesvirus infections including herpes simplex virus 1 & 2 and varicella zoster.
• Acyclovir inhibits viral DNA synthesis
• Bioavailability of acyclovir from the gastrointestinal tract is low.
• Bioavailability decreases as doses are increased.
• IV is the preferred route when high doses are required.

Cephalosporins: Mechanism of Action and Side Effects

• Cephalosporins are bactericidal antibiotics that inhibit bacterial cell wall synthesis by binding to penicillin-binding proteins.
• This disrupts peptidoglycan cross-linking in the cell wall, weakening structural integrity and leading to cell lysis and death.
• Common side effects include gastrointestinal disturbances (nausea, vomiting, diarrhea), hypersensitivity reactions (rash, fever, anaphylaxis), nephrotoxicity, and neurotoxicity with some cephalosporins.
• Superinfections (oral/vaginal candidiasis) from disrupted normal flora and bone marrow suppression/bleeding are possible but rare side effects.
• Headaches, dizziness, nausea, vomiting, and diarrhea are additional common side effects.

Cephalosporins: First Generation

• First-generation cephalosporins are commonly used to treat skin and soft-tissue infections caused by Staphylococcus and Streptococcus species.
• Other uses include respiratory tract infections (bronchitis and pneumonia), urinary tract infections, and bone and joint infections.
• They have good activity against gram-positive bacteria but limited coverage of gram-negative organisms.
• Cephalexin, cefazolin, and cephradine are examples of first-generation cephalosporins.

Penicillin Class

• Penicillins are beta-lactam antibiotics that inhibit bacterial cell wall synthesis.
• They bind to the enzyme DD-transpeptidase (penicillin-binding protein) preventing it from working, hindering the construction of robust bacterial cell walls.
• Some bacteria (like Staphylococcus aureus) have developed resistance from an enzyme called beta-lactamase or penicillinase, that breaks down the beta-lactam ring in penicillin.
• Basic penicillins include penicillin V (oral) penicillin G (intramuscular or intravenous).
• Broad-spectrum includes amoxicillin, ampicillin (oral, IM or IV).
• Anti-staphylococcal includes dicloxacillin, nafcillin, and oxacillin (IM or IV).
• Extended-spectrum includes piperacillin, commonly used in combination with beta-lactamase inhibitors (like tazobactam) usually administered intravenously.

Tetracyclines and Glycylcyclines

• Tetracyclines can cause permanent tooth discoloration, enamel hypoplasia, and possibly retard fetal skeletal development if taken during pregnancy.
• Other side effects include photosensitivity, altered intestinal/vaginal flora leading to diarrhea or candidiasis, bulging fontanelles in neonates, blood dyscrasias, and exacerbation of lupus.
• Gastrointestinal upset, rash, and enterocolitis also occur.
• For glycylcyclines like tigecycline, common adverse effects include nausea, vomiting, bradycardia, severe diarrhea, hepatotoxicity, hyperglycemia, QTc prolongation, and potentially life-threatening interstitial lung disease or pneumonitis.

Patient Assessment of Itching

• Location and distribution of the itching
• Duration and pattern (constant or intermittent)
• Severity and intensity of the itch
• Presence of any visible skin lesions or rashes
• Aggravating or relieving factors
• Associated symptoms like redness, swelling, pain, fever
• Recent illness, medications, or exposure to potential irritants
• History of skin conditions, allergies, or systemic diseases.
• Determine if the itch is generalized or localized; ask about scratching behaviors, assess mental status for psychogenic itch.
• Evaluate for potential underlying causes like dry skin, infections, liver or kidney disease, malignancy, or neuropathy.

Cefazolin

• Cefazolin (Ancef) is a first-generation cephalosporin antibiotic.
• Used for surgical prophylaxis and treatment of susceptible staphylococcal and streptococcal infections.
• Provides excellent coverage against gram-positive bacteria but limited activity against gram-negative organisms.
• Common side effects include gastrointestinal upset, hypersensitivity reactions, and superinfection (like candidiasis).
• Nurses should perform a baseline assessment for the patient (weight, vital signs, fever, fluid intake/output, lab results including CBC, renal and hepatic function, and potassium levels).

Macrolide Antibiotics

• Macrolides are a class of antibiotics used to treat infections caused by gram-positive and gram-negative bacteria.
• Macrolide medications include erythromycin, azithromycin, clarithromycin, and fidaxomicin.
• Erythromycin can be orally and intravenously administered, while azithromycin has an ophthalmic formulation.
• Azithromycin and clarithromycin have a longer duration of action, allowing less frequent dosing.
• Fidaxomicin is specifically for treating Clostridioides difficile-associated diarrhea.
• Common adverse effects include gastrointestinal disturbances, skin rash, and, in some cases, ototoxicity and hearing loss.

TMP-SMX

• Trimethoprim-sulfamethoxazole (TMP-SMX) is a broad-spectrum antibacterial agent effective against gram-positive and gram-negative bacteria.
• Often used to treat urinary tract infections, Pneumocystis jirovecii pneumonia in immunocompromised patients, acute exacerbations of chronic bronchitis, travelers' diarrhea, shigellosis, and cholera.
• Common side effects include nausea, vomiting, loss of appetite, rash, and photosensitivity.
• More serious adverse effects include bone marrow suppression, nephrotoxicity, hepatotoxicity, and hypersensitivity reactions like Stevens-Johnson syndrome or toxic epidermal necrolysis.

Ondansetron

• Ondansetron is a selective 5-HT3 receptor antagonist that blocks serotonin at the 5-HT3 receptors in the chemoreceptor trigger zone and gastrointestinal tract.
• It prevents nausea and vomiting caused by chemotherapy, radiation therapy, and surgery, making it effective for cancer treatments and anesthesia.
• Common side effects include headache, dizziness, and constipation; it can prolong the QT interval, potentially leading to dysrhythmias.
• It can cause serotonin syndrome characterized by skin flushing, tachycardia, and agitation. Use with caution in patients with long QT syndrome or those taking medications that prolong the QT interval.

Role of the RN during Perioperative Care

• Preoperative phase: Assess patient's health status and risk factors, provide preoperative teaching, obtain informed consent, ensure proper preoperative preparation (NPO status, skin prep, etc.), advocate for the patient, and coordinate care.

• Intraoperative phase: Act as the circulating nurse (monitoring patient, surgery, environment), manage patient positioning, medications, specimens, and surgical counts; serve as patient advocate for safety and dignity.

• Postoperative phase: Assess and monitor patient's recovery (vital signs, pain, surgical site, etc.), provide postoperative teaching on wound care, medications, and follow-up. Coordinate discharge planning and home care needs, advocate for the patient's ongoing care requirements.

Surgical Care Improvement Project (SCIP)

• A set of core compliance measures to reduce surgical complications, initiated in 2006.
• Focus areas: proper administration of prophylactic antibiotics, timely discontinuation of urinary catheters, and venous thromboembolism (VTE) prophylaxis.

National Patient Safety Goals

• Ensure accurate patient identification using at least two identifiers.
• Effective communication among the surgical team regarding critical elements of care (informed consent, preoperative verification, marking procedure site, safety checklist).
• Administer appropriate prophylactic antibiotics within one hour before incision.
• Implement evidence-based practices to prevent healthcare-associated infections (proper hair removal, hand hygiene, and aseptic techniques).
• Implement evidence-based practices to prevent venous thromboembolism (VTE) such as using appropriate prophylaxis and providing patient education.

Safety Concerns of Epidural Catheters

• Infection risk: Strict asepsis is crucial during insertion and maintenance to prevent contamination.
• Bleeding/hematoma: Coagulation status needs assessment to avoid neurological deficits.
• Catheter migration/shearing: Improper positioning may lead to ineffective analgesia or unintended injection.
• Medication errors: Verify the correct medication, concentration, and dosage.
• Respiratory depression: Opioid medications can cause respiratory depression, requiring close monitoring.
• Neurological injury: Trauma during insertion to the wrong space can damage nerves/spinal cord.

Spinal Headache and Blood Patch

• Spinal headache is a potential complication of epidural/spinal anesthesia, occurring in 70% of patients.
• It is often self-limiting and resolves with bed rest, analgesics, and hydration.
• In severe cases, an epidural blood patch is a safe and effective treatment for post-dural puncture headaches that don't resolve with conservative measures.

Prophylaxis Against Surgery-Related VTE

• Early ambulation, leg exercises, and pharmacological prophylaxis (low-molecular-weight heparin or other anticoagulants) are used.
• Mechanical prophylaxis like intermittent pneumatic compression devices and graduated compression stockings.
• Assessing risk factors to identify patients needing extended prophylaxis post-discharge.

Street Drugs and Anesthesia Effects

• Use of street drugs (cocaine, amphetamines, opioids) can significantly impact anesthesia effects and safety.
• Increase anesthesia requirements, leading to delayed emergence and respiratory depression.
• Marijuana use increases the risk of airway issues during intubation.

Dronabinol

• A synthetic form of tetrahydrocannabinol (THC), the main psychoactive component in marijuana.
• FDA-approved for treating nausea and vomiting associated with cancer chemotherapy.
• Can stimulate appetite and promote weight gain in patients with AIDS or undergoing chemotherapy.

Promethazine

• An antiemetic and sedative medication for nausea, vomiting, and motion sickness.
• Anti-dopaminergic action. Requires careful monitoring and assessment for side effects like dehydration, electrolyte imbalances, orthostatic hypotension, tachycardia, and extrapyramidal symptoms.
• Should not be used in patients with hepatic impairment, bone marrow suppression, conditions affected by anticholinergic effects (like glaucoma).

Ondansetron Mechanism of Action

• A selective 5-HT3 receptor antagonist, blocking serotonin at 5-HT3 receptors in the chemoreceptor trigger zone and gastrointestinal tract.

Role of the RN in 3 Perioperative Phases

• Preoperative: Assess health status, risk factors, provide preoperative teaching, ensure informed consent, coordinate care, document necessary information.
• Intraoperative: Monitor patient, surgery, and environment; manage positioning, meds., specimens, surgical counts; serve as patient advocate for safety and dignity; document all priorities, interventions, and any concerns.
• Postoperative: Assess patient's recovery (vital signs, pain, surgical site); provide wound care, meds. and follow-up; coordinate discharge planning and home care needs; advocate for ongoing care requirements.

This quiz covers the pharmacological aspects of valacyclovir, including its mechanisms of action, side effects, and advantages over other medications. It also explores the properties and usages of crystalloid solutions in therapy. Test your knowledge on these important medications and their clinical considerations.