Key Takeaways
- Antibiotics are classified by mechanism: cell wall synthesis inhibitors (penicillins, cephalosporins), protein synthesis inhibitors (macrolides, tetracyclines), DNA/RNA inhibitors (fluoroquinolones).
- Penicillin allergy may cross-react with cephalosporins; always check allergy status before dispensing.
- Opioid analgesics (morphine, oxycodone, hydrocodone) are Schedule II controlled substances with addiction potential.
- NSAIDs (ibuprofen, naproxen) can cause GI bleeding and should be used cautiously with anticoagulants.
- Benzodiazepines (-azepam) are Schedule IV controlled substances used for anxiety and seizures; can cause dependence.
Last updated: January 2026
Anti-infective, Analgesic, and CNS Medications
Quick Answer: This section covers three major drug categories: anti-infectives (antibiotics, antivirals, antifungals), analgesics (opioids, NSAIDs, acetaminophen), and CNS medications (antidepressants, anxiolytics, antiseizure drugs). Understanding mechanisms, common drugs, and key safety issues is essential.
Anti-infective Medications
Antibiotic Classes by Mechanism
| Mechanism | Drug Classes | Key Point |
|---|---|---|
| Cell Wall Synthesis Inhibitors | Penicillins, Cephalosporins, Carbapenems, Vancomycin | Bactericidal |
| Protein Synthesis Inhibitors | Macrolides, Aminoglycosides, Tetracyclines | Some bacteriostatic |
| DNA/RNA Synthesis Inhibitors | Fluoroquinolones, Metronidazole, Rifampin | Bactericidal |
| Folate Synthesis Inhibitors | Sulfonamides, Trimethoprim | Often combined (Bactrim) |
Penicillins (Suffix: -cillin)
| Generic Name | Brand Name | Spectrum | Key Points |
|---|---|---|---|
| amoxicillin | Amoxil | Broad | Most common; available as suspension |
| amoxicillin/clavulanate | Augmentin | Broad (beta-lactamase resistant) | Keep suspension refrigerated |
| penicillin VK | Pen-VK | Narrow | Strep throat treatment |
| ampicillin | Various | Broad | Often IV; used for meningitis |
Allergy Alert: Penicillin allergies can be life-threatening. Cross-reactivity with cephalosporins is approximately 1-2%.
Cephalosporins
| Generation | Examples | Brand Names | Coverage |
|---|---|---|---|
| 1st | cephalexin, cefazolin | Keflex, Ancef | Gram-positive focus |
| 2nd | cefuroxime, cefaclor | Ceftin, Ceclor | Improved gram-negative |
| 3rd | ceftriaxone, cefdinir | Rocephin, Omnicef | Broad gram-negative |
| 4th | cefepime | Maxipime | Extended spectrum |
| 5th | ceftaroline | Teflaro | MRSA coverage |
Macrolides (Suffix: -thromycin)
| Generic Name | Brand Name | Key Points |
|---|---|---|
| azithromycin | Zithromax, Z-pack | QT prolongation risk; 5-day course |
| clarithromycin | Biaxin | Drug interactions (CYP3A4) |
| erythromycin | Various | GI side effects; many interactions |
Fluoroquinolones (Suffix: -floxacin)
| Generic Name | Brand Name | Key Points |
|---|---|---|
| ciprofloxacin | Cipro | Avoid with dairy/antacids; photosensitivity |
| levofloxacin | Levaquin | Once daily; respiratory infections |
| moxifloxacin | Avelox | No renal adjustment needed |
Black Box Warning: Tendon rupture, peripheral neuropathy, CNS effects
Tetracyclines
| Generic Name | Brand Name | Key Points |
|---|---|---|
| doxycycline | Vibramycin, Doryx | Take with full glass of water; photosensitivity |
| tetracycline | Sumycin | Avoid dairy; don't give to children <8 years |
| minocycline | Minocin | Vertigo/dizziness common |
Key Interactions: Dairy products, antacids, iron decrease absorption
Antiviral Medications
| Condition | Generic Name | Brand Name | Key Points |
|---|---|---|---|
| Herpes/Shingles | acyclovir | Zovirax | Maintain hydration |
| Herpes/Shingles | valacyclovir | Valtrex | Prodrug of acyclovir; better absorption |
| Influenza | oseltamivir | Tamiflu | Start within 48 hours of symptoms |
| HIV | Many combinations | Biktarvy, Descovy, Truvada | Strict adherence required |
| Hepatitis C | sofosbuvir/velpatasvir | Epclusa | Curative in most cases |
Antifungal Medications
| Generic Name | Brand Name | Use | Key Points |
|---|---|---|---|
| fluconazole | Diflucan | Yeast infections | Many drug interactions |
| itraconazole | Sporanox | Systemic fungal infections | Take with food |
| terbinafine | Lamisil | Nail fungus | Liver monitoring |
| nystatin | Mycostatin | Oral/topical candida | Swish and swallow |
| clotrimazole | Lotrimin | Topical fungal | OTC available |
Analgesic Medications
Opioid Analgesics (Schedule II unless noted)
| Generic Name | Brand Name | Relative Potency | Schedule |
|---|---|---|---|
| morphine | MS Contin, Roxanol | 1 (reference) | C-II |
| oxycodone | OxyContin, Percocet | 1.5x morphine | C-II |
| hydrocodone | Vicodin, Norco | Similar to morphine | C-II |
| hydromorphone | Dilaudid | 4-5x morphine | C-II |
| fentanyl | Duragesic (patch) | 80-100x morphine | C-II |
| codeine | Tylenol #3 | 0.1x morphine | C-II |
| tramadol | Ultram | Weak opioid + SNRI | C-IV |
Common Side Effects: Constipation, nausea, sedation, respiratory depression Antidote: Naloxone (Narcan)
Non-Opioid Analgesics
| Generic Name | Brand Name | Max Daily Dose | Key Points |
|---|---|---|---|
| acetaminophen | Tylenol | 3,000-4,000 mg | Hepatotoxicity risk; in many combinations |
| ibuprofen | Advil, Motrin | 3,200 mg (Rx); 1,200 mg (OTC) | GI bleeding risk; avoid in kidney disease |
| naproxen | Aleve, Naprosyn | 1,500 mg | Longer acting than ibuprofen |
| meloxicam | Mobic | 15 mg | Once daily NSAID |
| celecoxib | Celebrex | 400 mg | COX-2 selective; less GI bleeding |
NSAID Warnings: GI bleeding, cardiovascular risk (except aspirin), renal impairment
Central Nervous System (CNS) Medications
Antidepressants
SSRIs (Selective Serotonin Reuptake Inhibitors - Suffix: -oxetine, -pram)
| Generic Name | Brand Name | Key Points |
|---|---|---|
| fluoxetine | Prozac | Long half-life; many interactions |
| sertraline | Zoloft | Most commonly prescribed |
| paroxetine | Paxil | Withdrawal symptoms; weight gain |
| escitalopram | Lexapro | Well-tolerated; anxiety |
| citalopram | Celexa | QT prolongation at high doses |
Black Box Warning: Increased suicidality in young adults (under 25)
SNRIs (Serotonin-Norepinephrine Reuptake Inhibitors)
| Generic Name | Brand Name | Key Points |
|---|---|---|
| duloxetine | Cymbalta | Also for neuropathy, fibromyalgia |
| venlafaxine | Effexor XR | Blood pressure monitoring; taper slowly |
Other Antidepressants
| Generic Name | Brand Name | Class | Key Points |
|---|---|---|---|
| bupropion | Wellbutrin | NDRI | No sexual side effects; seizure risk |
| trazodone | Desyrel | SARI | Often used for sleep |
| mirtazapine | Remeron | Tetracyclic | Weight gain; sedation |
Anxiolytics (Anti-anxiety)
Benzodiazepines (Suffix: -azepam, -am - Schedule IV)
| Generic Name | Brand Name | Duration | Key Points |
|---|---|---|---|
| alprazolam | Xanax | Short | High abuse potential |
| lorazepam | Ativan | Short-intermediate | Available IV; no active metabolites |
| diazepam | Valium | Long | Muscle relaxant; multiple uses |
| clonazepam | Klonopin | Long | Also for seizures |
Side Effects: Sedation, dependence, respiratory depression Antidote: Flumazenil
Non-Benzodiazepine Anxiolytics
| Generic Name | Brand Name | Key Points |
|---|---|---|
| buspirone | BuSpar | Non-controlled; takes 2-4 weeks to work |
| hydroxyzine | Vistaril, Atarax | Antihistamine; also for itching |
Antiseizure/Anticonvulsant Medications
| Generic Name | Brand Name | Key Points |
|---|---|---|
| phenytoin | Dilantin | NTI drug; gingival hyperplasia |
| valproic acid | Depakote | Teratogenic; monitor liver/platelets |
| carbamazepine | Tegretol | NTI drug; many interactions |
| levetiracetam | Keppra | Few interactions; first-line |
| lamotrigine | Lamictal | Rash risk; titrate slowly |
| gabapentin | Neurontin | Also for neuropathy; not controlled |
| pregabalin | Lyrica | Schedule V; neuropathy |
| topiramate | Topamax | Weight loss; kidney stones |
Exam Tip: Know opioid schedules, antibiotic classes with their suffixes, and which drugs require monitoring (NTI drugs, warfarin, digoxin).
Test Your Knowledge
Which antibiotic class works by inhibiting bacterial cell wall synthesis?
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B
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D
Test Your Knowledge
Which medication is the antidote for opioid overdose?
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B
C
D
Test Your Knowledge
A patient taking doxycycline should be counseled to avoid which of the following?
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B
C
D