Unit 8 Study Guide
What are adverse reactions and interactions with muscarinic agonists?
Muscarinic agonists are drugs that activate muscarinic receptors in the parasympathetic nervous system. A frequently prescribed example is bethanechol, which is commonly used to treat urinary retention and gastrointestinal motility issues. Due to its parasympathetic stimulation, bethanechol can cause several significant adverse reactions.
Cardiovascular effects often include hypotension, caused by peripheral vasodilation, and bradycardia, which results from increased vagal nerve activity. On the gastrointestinal front, patients may experience excessive salivation, increased gastric acid secretion, abdominal cramps, nausea, and diarrhea. These symptoms stem from enhanced smooth muscle contraction and gland secretion.
Patients with respiratory conditions, such as asthma or chronic obstructive pulmonary disease (COPD), face increased risks because muscarinic agonists may induce bronchoconstriction and increase bronchial secretions, potentially worsening their symptoms. Consequently, these drugs should be used cautiously or avoided in individuals with cardiovascular diseases, gastrointestinal obstruction, or pulmonary disorders.
If patients continue to be re-infected with UTIs, what medication prophylaxis should be given? Differentiate between reinfection and relapse.
Recurrent urinary tract infections (UTIs) are a common clinical challenge, especially among women. Treatment approaches vary based on whether infections represent reinfection or relapse, each having different causes and management strategies.
Reinfection occurs when a new bacterial infection develops after successfully treating a previous UTI. Common risk factors include sexual activity, spermicide use, or alterations in vaginal flora. For infrequent reinfections (1–2 episodes per year), each episode is treated with a short course of antibiotics. In cases of frequent reinfections, prophylactic antibiotic therapy—such as low-dose nitrofurantoin—may be appropriate.
In contrast, relapse happens when symptoms return shortly after finishing antibiotic therapy, usually due to the persistence of the original infecting organism. This pattern suggests an unresolved underlying issue like urinary tract obstruction, kidney stones, or chronic prostatitis in men. Such cases require further diagnostic evaluation and possibly extended or alternative antimicrobial treatment.
Nitrofurantoin is often the preferred antibiotic for uncomplicated cystitis because of its effectiveness and low likelihood of promoting antibiotic resistance.
| Aspect | Reinfection | Relapse |
|---|---|---|
| Underlying Cause | New bacterial exposure, often linked to behavior or contraceptive use | Persistence of the same bacterial organism |
| Timing of Recurrence | Occurs after full symptom resolution | Occurs soon after therapy completion |
| Treatment Strategy | Treat episodes individually; consider prophylaxis if frequent | Investigate structural/chronic causes; prolonged therapy may be needed |
| Frequency | Typically infrequent (1–2 episodes per year) | Rapid recurrence post-treatment |
Discuss the treatment for a pediatric patient with a UTI.
Management of urinary tract infections in children depends on age and clinical circumstances, focusing on both efficacy and safety. For children aged 6 to 12 years, methenamine hippurate may be used as a prophylactic agent for recurrent UTIs, particularly when no anatomical abnormalities exist. This medication works by releasing formaldehyde in acidic urine, which inhibits bacterial growth.
For neonates and infants younger than six months, initial treatment generally involves intravenous ampicillin combined with gentamicin. This regimen offers broad-spectrum coverage against common neonatal urinary pathogens while maintaining a favorable safety profile. Early diagnosis and prompt treatment in this age group are critical to prevent renal scarring and long-term complications.
Discuss the specific treatment for patients with enterococcal endocarditis.
Enterococcal endocarditis is challenging to treat due to the inherent resistance of Enterococcus species to many antibiotics. Monotherapy is often inadequate, especially in infections involving heart valves.
The recommended treatment consists of combination therapy to achieve synergistic bactericidal effects. Typically, a penicillin-class antibiotic such as ampicillin or penicillin G is combined with an aminoglycoside like gentamicin. This approach enhances bacterial killing and improves patient outcomes. Treatment courses are prolonged, reflecting the infection’s severity and complexity.
How is gonorrhea treated?
Gonorrhea, caused by Neisseria gonorrhoeae, requires effective and prompt treatment due to increasing antimicrobial resistance. Current guidelines emphasize the use of third-generation cephalosporins as the primary treatment to combat resistant strains.
These cephalosporins help prevent serious complications, such as pelvic inflammatory disease, infertility, and disseminated gonococcal infection. Adherence to these treatment guidelines is crucial to minimize further resistance development.
What is epinephrine used for? What is the mechanism of action?
Epinephrine is a nonselective adrenergic agonist that stimulates alpha (α₁, α₂) and beta (β₁, β₂) receptors, but does not act on dopamine receptors. It is commonly used in emergencies such as anaphylaxis, cardiac arrest, and severe asthma attacks.
Its mechanism involves α₁-mediated vasoconstriction, which raises blood pressure and decreases mucosal swelling, while β₂ receptor stimulation causes bronchodilation, improving airway patency. β₁ receptor activation increases heart rate and contractility, boosting cardiac output. These combined effects make epinephrine a vital treatment in life-threatening hypersensitivity reactions.
Which allergy medication is best for children? What are the side effects?
For managing allergies in children, second-generation antihistamines are generally preferred due to fewer sedative effects. These medications are safe when dosed according to the child’s age and weight.
Side effects can include drowsiness, dizziness, impaired coordination, fatigue, gastrointestinal upset, and confusion, similar to those seen in adults. Notably, promethazine is contraindicated in children under two years old because it can cause fatal respiratory depression and should never be prescribed in this age group.
What should the healthcare provider look for when discontinuing gout medications?
When stopping gout medications, careful monitoring for early signs of adverse reactions is essential to avoid serious complications.
Colchicine should be discontinued immediately if severe gastrointestinal symptoms such as diarrhea, vomiting, or abdominal pain occur, as these may indicate toxicity. Allopurinol must be stopped at the first sign of rash, fever, or systemic symptoms, which could signal a potentially life-threatening hypersensitivity reaction. Early recognition and intervention can prevent progression to severe cutaneous or systemic conditions.
References
American Academy of Pediatrics Committee on Infectious Diseases. (2019). Red Book: 2018–2021 report of the Committee on Infectious Diseases. American Academy of Pediatrics.
Brunton, L. L., Hilal-Dandan, R., & Knollmann, B. C. (2018). Goodman & Gilman’s the pharmacological basis of therapeutics (13th ed.). McGraw-Hill Education.
Katzung, B. G., Masters, S. B., & Trevor, A. J. (2022). Basic and clinical pharmacology (15th ed.). McGraw-Hill Education.
Mandell, G. L., Bennett, J. E., & Dolin, R. (2020). Principles and practice of infectious diseases (9th ed.). Elsevier.