Comprehensive Pharmacology: Dosage Calculations, Antibiotics, and Adverse Effects

What is the basic dosage calculation formula?

Desired ÷ Have × Quantity = Amount to give.

What is the formula for IV infusion rate in mL/hr?

Total mL ÷ hours = mL/hr.

What is the formula for IV drops/min?

mL × drop factor ÷ minutes = gtt/min.

What is the most important rule before doing a medication calculation?

Make sure the units match.

How many mg are in 1 gram?

1 g = 1,000 mg.

How many mcg are in 1 mg?

1 mg = 1,000 mcg.

How many mL are in 1 liter?

1 L = 1,000 mL.

How many pounds are in 1 kg?

1 kg = 2.2 lb.

How many mL are in 1 teaspoon?

1 tsp = 5 mL.

How many mL are in 1 tablespoon?

1 tbsp = 15 mL.

What is the major concern with penicillins?

Allergic reactions, including anaphylaxis.

What should the nurse assess before giving a penicillin?

Ask about a history of penicillin allergy.

What are signs of anaphylaxis?

Difficulty breathing, wheezing, facial swelling, hypotension, and tachycardia.

What should the nurse do if a patient develops anaphylaxis?

Stop the medication and treat the emergency according to protocol.

What should patients know about completing antibiotics?

Finish the entire prescribed course even if they feel better.

Why should patients finish their antibiotics?

Stopping early can cause treatment failure and contribute to antibiotic resistance.

What is an important concern with cephalosporins?

Allergic reactions, especially in patients with serious beta-lactam allergies.

What should the nurse ask before administering a cephalosporin?

Ask about allergies to cephalosporins and penicillins.

What are common adverse effects of cephalosporins?

GI upset, diarrhea, nausea, and rash.

What are carbapenems?

Broad-spectrum antibiotics used for serious bacterial infections.

What are examples of carbapenems?

Imipenem and meropenem.

What serious adverse effect can carbapenems cause?

Seizures, especially with certain carbapenems and renal impairment.

What should be monitored with carbapenems?

Renal function, infection response, allergic reactions, and neurologic changes.

What is vancomycin commonly used to treat?

Serious gram-positive infections, including MRSA.

What are two major toxicities of IV vancomycin?

Nephrotoxicity and ototoxicity.

What laboratory value is important with vancomycin?

Serum creatinine and BUN to monitor renal function.

What is Red Man Syndrome?

A reaction caused by rapid IV infusion of vancomycin that can cause flushing, itching, and hypotension.

How can Red Man Syndrome be prevented?

Infuse vancomycin slowly according to facility protocol.

A patient receiving vancomycin develops flushing and hypotension. What should the nurse suspect?

Red Man Syndrome.

What are tetracyclines?

An antibiotic class that includes medications such as doxycycline and tetracycline.

What is a major adverse effect of tetracyclines?

Photosensitivity.

What should patients taking tetracyclines know about sunlight?

Use sunscreen, protective clothing, and avoid excessive sunlight.

Why should tetracyclines generally not be given to young children?

They can cause permanent tooth discoloration and affect bone development.

Why should tetracyclines be separated from antacids and certain minerals?

Calcium, magnesium, aluminum, and iron can decrease absorption.

What foods or supplements can interfere with tetracycline absorption?

Dairy products, calcium, iron, magnesium, and aluminum-containing antacids.

What are examples of macrolides?

Azithromycin, erythromycin, and clarithromycin.

What is a major cardiac concern with macrolides?

QT prolongation, which can cause dysrhythmias.

What should the nurse assess with macrolides?

Cardiac history, QT concerns when appropriate, liver function, and GI effects.

What is a common adverse effect of macrolides?

GI upset, especially nausea and diarrhea.

What are examples of aminoglycosides?

Gentamicin, tobramycin, and amikacin.

What are the two major toxicities of aminoglycosides?

Ototoxicity and nephrotoxicity.

What is the easiest way to remember aminoglycoside toxicity?

Think EARS + KIDNEYS.

What symptoms may indicate ototoxicity?

Tinnitus, hearing loss, vertigo, and balance problems.

What lab is especially important with aminoglycosides?

Serum creatinine and BUN to monitor renal function.

Why must aminoglycosides be monitored carefully?

They have a narrow therapeutic range and can cause serious kidney and hearing damage.

A patient taking gentamicin reports ringing in the ears. What should the nurse suspect?

Ototoxicity.

What are examples of fluoroquinolones?

Ciprofloxacin and levofloxacin.

What major adverse effect is associated with fluoroquinolones?

Tendon injury or tendon rupture.

What tendon is especially associated with fluoroquinolone injury?

The Achilles tendon.

What should a patient taking a fluoroquinolone report immediately?

Tendon pain or swelling.

What other important adverse effects can occur with fluoroquinolones?

QT prolongation, CNS effects, photosensitivity, peripheral neuropathy, and tendon injury.

What products should be separated from fluoroquinolones?

Products containing aluminum, magnesium, calcium, or iron.

Why should antacids be separated from fluoroquinolones?

They can bind the medication and reduce absorption.

What is an example of a sulfonamide antibiotic?

Trimethoprim-sulfamethoxazole, also called TMP-SMX.

What serious skin reaction can occur with sulfonamides?

Stevens-Johnson syndrome.

What should a patient taking a sulfonamide report immediately?

Severe rash, blisters, peeling skin, mouth sores, or fever.

What should patients taking sulfonamides know about sunlight?

Use sun protection because photosensitivity can occur.

What is important hydration teaching with sulfonamides?

Drink adequate fluids unless contraindicated to help reduce kidney complications.

What labs may be monitored with TMP-SMX?

CBC, renal function, and potassium when clinically indicated.

What is nitrofurantoin primarily used to treat?

Urinary tract infections.

How should nitrofurantoin be taken?

Take it with food or milk to improve tolerance and absorption.

What can happen to urine color with nitrofurantoin?

Urine may become dark yellow or brown.

What serious toxicity can occur with long-term nitrofurantoin therapy?

Pulmonary toxicity.

What symptoms may indicate pulmonary toxicity from nitrofurantoin?

Cough, shortness of breath, or chest pain.

What organ function is important when giving nitrofurantoin?

Renal function.

What is isoniazid (INH) used for?

Treatment and prevention of tuberculosis.

What is the biggest toxicity of isoniazid?

Hepatotoxicity.

What symptoms suggest isoniazid liver toxicity?

Fatigue, weakness, loss of appetite, nausea, dark urine, jaundice, and right upper quadrant pain.

What vitamin is often given with isoniazid?

Vitamin B6, also called pyridoxine.

Why is vitamin B6 given with isoniazid?

To prevent peripheral neuropathy.

What symptoms indicate peripheral neuropathy from INH?

Numbness, tingling, burning, or pain in the hands and feet.

What should be monitored with INH?

Liver function, signs of hepatotoxicity, and neurologic symptoms.

What is rifampin used for?

Treatment of tuberculosis, usually as part of combination therapy.

What happens to body fluids with rifampin?

Urine, sweat, tears, and saliva may become orange-red.

Is orange urine necessarily an adverse reaction to rifampin?

No. Orange-red discoloration of body fluids can be an expected medication effect.

What important type of medication interaction occurs with rifampin?

Rifampin is a strong enzyme inducer and can decrease the effectiveness of many medications.

What medication effectiveness can rifampin reduce that is commonly tested?

Hormonal contraceptives.

What organ should be monitored with rifampin?

The liver.

What is the easiest way to remember INH?

INH = liver toxicity + peripheral neuropathy → give B6.

What is the easiest way to remember rifampin?

Rifampin = orange body fluids + major drug interactions + liver monitoring.

What is amphotericin B used to treat?

Serious systemic fungal infections.

What is the biggest toxicity associated with amphotericin B?

Nephrotoxicity.

What electrolyte problems can amphotericin B cause?

Hypokalemia and hypomagnesemia.

What labs should be monitored with amphotericin B?

BUN, creatinine, potassium, and magnesium.

What infusion-related effects can occur with amphotericin B?

Fever, chills, headache, nausea, and hypotension.

A patient receiving amphotericin B has rising creatinine and decreased urine output. What should the nurse suspect?

Nephrotoxicity.

What is a major toxicity of ketoconazole?

Hepatotoxicity.

What should be monitored with ketoconazole?

Liver function.

What symptoms suggest liver injury from ketoconazole?

Dark urine, jaundice, fatigue, nausea, and right upper quadrant pain.

What is metronidazole commonly used to treat?

Certain anaerobic bacterial and protozoal infections.

What common taste disturbance can metronidazole cause?

A metallic taste.

What urine color change can occur with metronidazole?

Dark urine.

What is the biggest patient teaching point with metronidazole?

Avoid alcohol.

Why should alcohol be avoided with metronidazole?

It can cause a disulfiram-like reaction with nausea, vomiting, flushing, headache, and abdominal cramps.

What should a patient taking metronidazole do if they develop numbness or tingling in their feet?

Notify the provider because this can indicate peripheral neuropathy.

A patient taking metronidazole reports a metallic taste. What should the nurse do?

Explain that a metallic taste can occur with metronidazole.

What is acyclovir used to treat?

Herpesvirus infections such as herpes simplex and herpes zoster.

What is an important adverse effect of acyclovir?

Kidney toxicity, especially with IV therapy or inadequate hydration.

What is important patient teaching with acyclovir?

Maintain adequate hydration unless fluid restriction is prescribed.

Does acyclovir cure herpes?

No. It decreases viral replication and symptoms but does not eradicate the virus.