A 32-year-old woman presents with progressive ptosis, diplopia, and bulbar weakness. Serology is positive for anti-acetylcholine receptor (AChR) antibodies. She is diagnosed with generalized myasthenia gravis (MG). What is the drug of choice for initial symptomatic management?

Explanation

## Initial Symptomatic Management in Myasthenia Gravis **Key Point:** Pyridostigmine is the first-line symptomatic agent in MG, providing rapid but temporary relief of muscle weakness. ### Mechanism of Action Pyridostigmine is an acetylcholinesterase inhibitor that increases acetylcholine concentration at the neuromuscular junction by preventing enzymatic degradation. This compensates for the reduced number of functional AChR due to antibody-mediated destruction. ### Clinical Use - **Onset:** Rapid (15–30 minutes orally; 2–5 minutes IV) - **Duration:** 3–6 hours (short-acting) - **Dosing:** 30–60 mg orally every 4–6 hours; maximum 1.5 g/day - **Role:** Symptomatic relief only; does NOT alter disease course or prevent progression **Clinical Pearl:** Pyridostigmine is often called a "bridge" therapy because it provides immediate symptom control while waiting for immunosuppressive agents (azathioprine, prednisolone, mycophenolate) to take effect (which may take weeks to months). ### Why Pyridostigmine First? 1. **Rapid onset** — provides immediate functional improvement 2. **Safe profile** — minimal systemic toxicity when dosed appropriately 3. **Reversible** — effects wear off quickly if adverse effects occur 4. **Non-immunosuppressive** — can be used alongside immunotherapy without additive myelosuppression **High-Yield:** The anticholinergic side effects (diarrhea, salivation, bronchospasm) are dose-related and managed by reducing dose or adding atropine; these are NOT reasons to avoid the drug in MG. ### Comparison with Other Options | Agent | Role in MG | Onset | Use | |-------|-----------|-------|-----| | Pyridostigmine | Symptomatic | Minutes–hours | First-line, immediate relief | | Prednisolone | Immunosuppressive | Weeks | Second-line, disease-modifying | | Azathioprine | Immunosuppressive | Weeks–months | Steroid-sparing agent | | Mycophenolate mofetil | Immunosuppressive | Weeks–months | Alternative steroid-sparing agent | **Warning:** Do NOT confuse pyridostigmine (symptomatic) with immunosuppressive agents (disease-modifying). Pyridostigmine alone does not prevent progression or induce remission.