Cefepime is a fourth-generation cephalosporin antibiotic with broad-spectrum activity against both gram-positive and gram-negative organisms, including Pseudomonas aeruginosa. It works by inhibiting bacterial cell wall synthesis through binding to penicillin-binding proteins, leading to cell lysis and death.
Clinically, cefepime is commonly used in hospital settings for serious infections such as pneumonia, febrile neutropenia, urinary tract infections, skin infections, and intra-abdominal infections. It’s typically administered intravenously, with doses often ranging from 1 to 2 grams every 8 to 12 hours depending on the indication and renal function.
From a pharmacokinetic standpoint, cefepime is primarily renally eliminated, so dose adjustments are required in patients with impaired kidney function. Failure to reduce the dose appropriately can lead to neurotoxicity — one of the key adverse effects associated with cefepime — manifesting as encephalopathy, confusion, myoclonus, or seizures, particularly in elderly or renally impaired patients.
Common side effects include gastrointestinal upset and rash. Cefepime has relatively limited drug interactions, though concurrent nephrotoxic agents can increase the risk of renal injury.
Midodrine is an oral alpha-1 agonist most commonly used for the treatment of symptomatic orthostatic hypotension. Its mechanism of action is through peripheral vasoconstriction, which helps increase blood pressure. Because of its short duration of action, it is typically dosed three times daily, with the last dose recommended in the late afternoon to reduce the risk of hypertension at night.
Clinically, midodrine is often considered when non-pharmacologic strategies for orthostatic hypotension (such as increased salt/fluid intake, compression stockings, or physical counter-maneuvers) are not enough. Pharmacists should also be aware of prescribing cascades—such as urinary retention leading to tamsulosin initiation—that can arise when midodrine is used.
Midodrine is generally not metabolized through cytochrome P450 pathways, so significant drug–drug interactions are less common. However, caution should be exercised with other agents that can raise blood pressure (like decongestants) or slow the heart rate (such as beta-blockers). Monitoring parameters include blood pressure, pulse, symptoms of urinary retention, and the patient’s overall response to therapy.
Senna is a stimulant laxative. Its pharmacological activity comes from natural compounds called sennosides. Metabolites act locally in the colon to stimulate peristalsis, thereby accelerating bowel movements. While osmotic laxatives are generally considered first-line laxative agents, this makes senna a useful alternative for the short-term treatment of constipation.
The pharmacokinetics of senna are unique in that its onset of action typically takes 6 to 12 hours after oral administration, reflecting the time required for colonic bacteria to metabolize sennosides into active compounds. This delayed onset makes senna better suited for bedtime dosing when overnight relief is desired.
Although senna is effective, its use carries potential adverse effects. Common side effects include abdominal cramping, diarrhea, and, rarely, electrolyte disturbances such as hypokalemia. Chronic or excessive use can lead to dependency and possibly melanosis coli, a benign but visible pigmentation of the colon lining.
Drug interactions may occur, particularly with medications affected by potassium levels, such as digoxin or diuretics. For these reasons, senna is generally recommended for short-term use, with emphasis on evaluating underlying causes of constipation before long-term therapy is considered.
On this podcast, I cover ciprofloxacin pharmacology. Ciprofloxacin is one of the most widely recognized fluoroquinolone antibiotics and has been on the market for decades. Because of its broad utility, it often comes up in practice, but it also carries significant adverse effect concerns and boxed warnings that pharmacists and prescribers need to keep in mind.
From a pharmacology standpoint, ciprofloxacin works by inhibiting bacterial DNA gyrase and topoisomerase IV, enzymes that are essential for bacterial DNA replication, transcription, and repair. This action gives ciprofloxacin bactericidal activity against a variety of gram-negative organisms, including E. coli, Klebsiella, Enterobacter, and Pseudomonas aeruginosa. It also has some gram-positive activity, though it is generally not the best choice for strep infections.
Ciprofloxacin comes in multiple dosage forms, including oral tablets, oral suspension, and intravenous formulations, which makes it flexible across care settings. I discuss the conversion of IV and PO formulations.
Pharmacokinetics are important to consider. Ciprofloxacin is primarily renally eliminated, so dose adjustments are necessary in patients with impaired kidney function. Distribution into tissues is generally good, but it has limited activity in the lungs against Streptococcus pneumoniae, which is why it is not a first-line option for community-acquired pneumonia.
Adverse effects are a major concern. The fluoroquinolone class carries multiple boxed warnings. Ciprofloxacin has been associated with tendon rupture, peripheral neuropathy, CNS effects such as agitation or seizures, and exacerbation of myasthenia gravis. More recent warnings include the risk for aortic aneurysm and hypoglycemia or hyperglycemia, particularly in older adults or those with comorbidities. On top of these boxed warnings, ciprofloxacin can also prolong the QT interval and cause GI upset.
Drug interactions are another big factor in practice. Ciprofloxacin is a CYP1A2 inhibitor, which can raise levels of drugs like theophylline, tizanidine, and clozapine. It also interacts with polyvalent cations such as calcium, magnesium, iron, and aluminum, which can dramatically reduce its absorption—sometimes by more than 50%. This is a common reason for treatment failure if counseling isn’t provided.
From a dosing perspective, ciprofloxacin is usually given 250–750 mg orally twice daily or 400 mg IV every 8–12 hours depending on the indication and severity of infection. Renal dosing adjustments are needed as kidney function declines.
In summary, ciprofloxacin is a powerful antibiotic when used appropriately. It remains an option for urinary tract infections, complicated intra-abdominal infections, and some cases of hospital-acquired pneumonia, but its use must be balanced with the potential for significant adverse effects and interactions. For pharmacists, educating patients on drug interactions, counseling about boxed warnings, and ensuring correct dosing in renal impairment are some of the most valuable interventions when ciprofloxacin shows up on a medication list.
Vilazodone (brand name Viibryd) is an antidepressant with a unique pharmacologic profile compared to most other agents in the SSRI class. While not a first-line choice for every patient, understanding its mechanism, adverse effects, and interaction profile is essential for optimizing therapy and preventing downstream prescribing problems.
Mechanism of Action Vilazodone is classified as a selective serotonin reuptake inhibitor (SSRI) and a partial agonist at the 5-HT1A receptor. The SSRI activity increases synaptic serotonin by blocking the serotonin transporter, while partial agonism at 5-HT1A receptors may contribute to antidepressant effects and potentially reduce certain SSRI-associated adverse effects (though clinical evidence for this benefit is mixed).
Adverse Effects
GI effects – diarrhea, nausea, and vomiting are frequent early in therapy. Taking the medication with food can help minimize these.
Insomnia – often dose-related; morning dosing may help.
Sexual dysfunction – may be slightly lower than with some SSRIs but still present.
Serotonin syndrome – rare but serious, particularly if combined with other serotonergic drugs.
Discontinuation syndrome – abrupt cessation can lead to dizziness, irritability, and flu-like symptoms.
Drug Interactions Vilazodone is primarily metabolized by CYP3A4. This means:
CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin, ritonavir) can increase vilazodone concentrations, potentially worsening side effects—dose reductions may be required.
CYP3A4 inducers (e.g., carbamazepine, rifampin, St. John’s Wort) can lower drug levels, reducing effectiveness.
Other serotonergic agents (e.g., triptans, SNRIs, MAOIs, tramadol, linezolid) increase the risk of serotonin syndrome.
Antiplatelets and anticoagulants – SSRIs can impair platelet aggregation, increasing bleeding risk when combined with aspirin, NSAIDs, or warfarin.
Prescribing Cascade Examples Vilazodone’s adverse effects can easily lead to unnecessary prescriptions if side effects aren’t recognized:
GI upset → Acid suppression therapy – Diarrhea or nausea prompts the addition of proton pump inhibitors or antiemetics, instead of adjusting vilazodone dose or timing.
Insomnia → Hypnotic initiation – Trouble sleeping results in adding zolpidem or trazodone, without reassessing morning dosing or vilazodone’s role.
Sexual dysfunction → PDE5 inhibitor prescription – Erectile dysfunction leads to sildenafil use, when the root cause is vilazodone’s serotonergic activity.
Vilazodone’s combination of SSRI and 5-HT1A partial agonist activity makes it somewhat distinct, but its side effect profile and interactions require the same careful monitoring as other antidepressants. Healthcare professionals can play a key role in catching early signs of adverse effects, preventing prescribing cascades, and ensuring drug–drug interactions are managed appropriately.
Solifenacin is a bladder antimuscarinic medication most commonly used for overactive bladder (OAB) with symptoms of urinary frequency, urgency, and urge incontinence. Like other agents in its class, understanding the pharmacology can help anticipate potential side effects, drug interactions, and downstream prescribing problems.
Mechanism of Action
Solifenacin selectively blocks muscarinic M3 receptors in the bladder detrusor muscle. Inhibiting these receptors reduces involuntary bladder contractions, increases bladder capacity, and delays the urge to void. While M3 selectivity may theoretically reduce side effects compared to nonselective antimuscarinics, in clinical practice, many anticholinergic effects still occur.
Adverse Effects
Because muscarinic receptors are present throughout the body, solifenacin can lead to a range of anticholinergic adverse effects:
Dry mouth – among the most common, can be significant enough to cause dental issues with long-term use.
Constipation – especially problematic in older adults; severe cases may require hospitalization.
Blurred vision – due to impaired accommodation.
Cognitive impairment – increased risk in older adults, particularly with cumulative anticholinergic burden.
Urinary retention – paradoxical worsening in patients with bladder outlet obstruction.
Drug Interactions
CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin, ritonavir) can increase solifenacin plasma concentrations, raising the risk of side effects.
Other anticholinergics (e.g., diphenhydramine, tricyclic antidepressants, other bladder antimuscarinics) can result in additive toxicity and higher anticholinergic burden.
QT-prolonging drugs (e.g., amiodarone, certain fluoroquinolones) may have additive cardiac risk since solifenacin has been associated with QT prolongation in rare cases.
Prescribing Cascade Examples
Constipation → Laxative initiation – A patient starts solifenacin for OAB and develops severe constipation, leading to chronic use of stimulant laxatives like senna or bisacodyl.
Dry mouth → Mouth rinse prescription – Dry mouth is treated with saliva substitutes or prescription rinses, instead of reassessing the anticholinergic therapy.
Cognitive decline → Donepezil initiation – In older adults, cognitive impairment may be mistaken for dementia progression, leading to cholinesterase inhibitor prescribing—directly counteracting the anticholinergic effects of solifenacin.
Solifenacin can be an effective treatment for OAB, but the risk of adverse effects and prescribing cascades—especially in older adults—cannot be ignored. Healthcare professionals should regularly review the indication, monitor for anticholinergic burden, and look for opportunities to deprescribe when appropriate.
In this episode, we break down itraconazole—a potent antifungal with a lot of baggage. If you’re a pharmacist, clinician, or student who needs to understand how this drug works and why it can be tricky to use, this episode is for you.
We start with the basics. Itraconazole blocks 14α-demethylase, an enzyme fungi need to make their cell membranes. That disruption kills or slows the fungus. It works against tough bugs like Aspergillus, Histoplasma, and Blastomyces, plus common skin infections.
Side effects? Nausea, liver enzyme elevations, and more seriously, heart failure. Yes, itraconazole has a black box warning for worsening or causing congestive heart failure. If your patient has heart issues, think twice.
Drug interactions are everywhere. Itraconazole is a strong CYP3A4 inhibitor. It can raise levels of drugs like statins, benzos, calcium channel blockers, and immunosuppressants—sometimes to dangerous levels. Don’t co-prescribe without checking.
In this episode of our pharmacology podcast, we take a deep dive into the pharmacology of levomilnacipran (Fetzima), a unique serotonin-norepinephrine reuptake inhibitor (SNRI) approved for the treatment of major depressive disorder (MDD) in adults. Designed for pharmacy students, clinicians, and anyone interested in psychopharmacology, this episode breaks down what makes levomilnacipran different from other antidepressants and how to use it effectively in clinical practice.
We explore levomilnacipran’s mechanism of action, which features a greater affinity for norepinephrine reuptake inhibition compared to serotonin—an uncommon trait among SNRIs. This pharmacologic profile gives it a distinctive effect on energy, motivation, and physical symptoms of depression. Listeners will also learn about its pharmacokinetics, including once-daily dosing, renal elimination, and metabolism via the CYP3A4 pathway—making drug interactions an important consideration.
The episode also covers levomilnacipran side effects, including common adverse reactions like nausea, dry mouth, constipation, and increased heart rate or blood pressure. We’ll also highlight rare but serious risks like serotonin syndrome and urinary hesitation.
Because levomilnacipran drug interactions can impact safety and efficacy, we review important combinations to avoid, such as CYP3A4 inhibitors (e.g., ketoconazole), serotonergic drugs, and blood pressure-altering agents. For pharmacists and prescribers, this is a key segment to help guide safer medication use and monitoring.
Finally, we wrap up with clinical pearls for starting, titrating, and monitoring levomilnacipran therapy—including renal dose adjustments and differences with duloxetine.
Whether you’re studying for boards or optimizing your patient’s antidepressant regimen, this episode delivers a concise, evidence-based overview of levomilnacipran pharmacology in a digestible, podcast-friendly format.
Asenapine is an atypical antipsychotic that acts as an antagonist at multiple receptors, including dopamine D2 and serotonin 5-HT2A, contributing to its antipsychotic and mood-stabilizing effects.
Adverse effects of asenapine include somnolence, dizziness, and extrapyramidal symptoms.
Because asenapine is significantly metabolized by CYP1A2, inhibitors or inducers of these enzymes can affect its plasma concentrations.
Co-administration with other CNS depressants may increase the risk of sedation and impaired cognitive or motor function.
Asenapine can prolong the QT interval, so caution is advised when used with other medications that affect cardiac conduction.
Ketoconazole is an imidazole antifungal that works by inhibiting fungal cytochrome P450 14α-demethylase, an enzyme essential for ergosterol synthesis, which disrupts fungal cell membrane integrity.
Common adverse effects of ketoconazole include nausea, vomiting, abdominal pain, and elevated liver enzymes, with hepatotoxicity being a notable concern.
Ketoconazole carries a boxed warning for severe hepatotoxicity, including cases of liver failure and death, and should not be used as a first-line treatment for fungal infections when other safer antifungals are available.
Another boxed warning highlights ketoconazole’s potential to prolong the QT interval, increasing the risk for life-threatening ventricular arrhythmias such as torsades de pointes.
Ketoconazole is a strong inhibitor of CYP3A4 and can cause significant drug interactions by increasing serum concentrations of medications metabolized by this pathway, including statins, certain benzodiazepines, and some antiarrhythmic.
