Most students study pharmacology as a list of drug names. The students who write the best essays study it as a small set of causal threads that reappear in every lecture. Here are the four threads that make the L1–L6 material hang together.
To calm a cell down you either step on the brakes (make the inside more negative) or cut the gas pedal (stop positive charge from entering). Every drug that 'slows' the nervous system is doing one of those two things.
要讓細胞冷靜下來，只有兩招：踩剎車（讓細胞內部變得更負，超極化）或切斷油門（阻止正電荷進入）。所有讓神經系統『慢下來』的藥，本質上都屬於這兩類之一。
| Lecture | English | 中文邏輯 |
|---|---|---|
| L2 Pharmacodynamics | Agonist = pushes a receptor toward firing; antagonist = blocks it. Competitive vs non-competitive = different ways to cut the gas or jam the brake. | 促效劑把受體推向放電，拮抗劑擋住它。競爭性與非競爭性拮抗 = 切油門或卡住剎車的兩種方式。 |
| L3 Autonomic Nervous System | Sympathetic = gas pedal (β-receptors speed the heart, dilate bronchi). Parasympathetic = brake (muscarinic receptors slow the heart, contract the gut). | 交感神經 = 油門（β 受體加快心跳、擴張支氣管）。副交感神經 = 剎車（毒蕈鹼受體減慢心跳、收縮腸道）。 |
| L6 CNS | Barbiturates / benzodiazepines amplify GABA -> Cl⁻ inflow = hard brake. Anticonvulsants that block Na⁺/Ca²⁺ channels or AMPA = cut the gas. | 巴比妥／苯二氮䓬增強 GABA -> 氯離子湧入 = 死踩剎車。阻斷 Na⁺/Ca²⁺ 通道或 AMPA 的抗癲藥 = 切斷油門。 |
Many diseases are not 'too much of one thing' but 'too much of A relative to B'. You can fix the seesaw from either side: push the low end up or pull the high end down.
很多疾病不是『某種東西太多』，而是『A 相對於 B 失衡』。修天平可以從兩端下手：把低的那端拉起來，或把高的那端壓下去。
| Lecture | English | 中文邏輯 |
|---|---|---|
| L3 ANS | Sympathomimetics raise NE/ACh tone; sympatholytics lower it. The clinical choice depends on which side of the autonomic seesaw is misbehaving. | 擬交感藥提升 NE/ACh 張力；抗交感藥降低它。選藥取決於自律神經天平的哪一端出問題。 |
| L4 Cardiovascular | BP = CO × TPR. You can lower BP by reducing cardiac output (β-blockers) or by dilating vessels (vasodilators, CCBs). Same target, two sides of the equation. | 血壓 = 心輸出量 × 周邊阻力。降血壓可以減少心輸出（β 阻斷劑）或擴張血管（血管擴張劑、鈣離子通道阻斷劑）。同一目標，方程式的兩端。 |
| L6 CNS | Parkinson's = dopamine low, ACh relatively high. Treat with dopaminergics (levodopa) or anticholinergics (benztropine). Alzheimer's = ACh shortage -> cholinesterase inhibitors. | 帕金森氏症 = 多巴胺低、ACh 相對高。用多巴胺藥（levodopa）或抗膽鹼藥（benztropine）。阿茲海默症 = ACh 不足 -> 膽鹼酯酶抑制劑。 |
The BBB blocks >98% of molecules. Only small, lipid-soluble drugs pass by passive diffusion. This single physical rule shapes dosing routes, prodrugs, and the whole field of CNS drug design.
血腦屏障擋住超過 98% 的分子。只有小分子、脂溶性藥物能靠被動擴散通過。這一條物理規則決定了給藥途徑、前驅藥設計，以及整個中樞藥物開發領域。
| Lecture | English | 中文邏輯 |
|---|---|---|
| L1 ADME | BBB, first-pass metabolism, ion trapping, and route of administration are all versions of the same question: how much active drug reaches its site of action? | BBB、首渡代謝、離子陷阱、給藥途徑都是同一個問題的不同版本：有多少活性藥物到達作用部位？ |
| L5 Respiratory | Inhalation bypasses systemic distribution and deposits drug directly in the lungs. The device is as important as the molecule. | 吸入繞過全身分布，直接把藥送到肺部。裝置的重要性不亞於分子本身。 |
| L6 CNS | Dopamine cannot cross the BBB; levodopa can. Carbidopa blocks peripheral conversion without entering the brain — the textbook prodrug + protector pair. | 多巴胺過不了 BBB；levodopa 可以。Carbidopa 只在大腦外阻斷周邊轉化，不進腦 —— 這是前驅藥與保護劑的教科書組合。 |
A symptom like pain or bronchospasm can be triggered through different receptor pathways. The drug you choose should match the lock that is actually being turned in that disease.
疼痛或支氣管痙攣等症狀，可以經由不同受體路徑觸發。選藥要對上那個病真正被轉動的鎖。
| Lecture | English | 中文邏輯 |
|---|---|---|
| L3 ANS | α1/α2/β1/β2/β3 and M/N receptors are different locks in different organs. Subtype selectivity explains why salbutamol relaxes bronchi but not blood vessels. | α1/α2/β1/β2/β3 與 M/N 受體是不同器官的不同鎖。亞型選擇性解釋了為什麼 salbutamol 能放鬆支氣管卻不影響血管。 |
| L5 Respiratory | Asthma vs COPD, bronchospasm vs inflammation, histamine vs leukotrienes — each lock gets its own drug class: β2 agonists, muscarinic antagonists, leukotriene modifiers, PDE4 inhibitors. | 哮喘對 COPD、支氣管痙攣對發炎、組織胺對白三烯 —— 每把鎖對應一類藥：β2 促效劑、毒蕈鹼拮抗劑、白三烯調節劑、PDE4 抑制劑。 |
| L6 CNS | Pain: μ-receptor in CNS vs COX in periphery. Vomiting: 5-HT₃, NK1, M, D₂/H₁. Each trigger is a different lock requiring a different key. | 疼痛：中樞 μ 受體對周邊 COX。嘔吐：5-HT₃、NK1、M、D₂/H₁。每個觸發點都是不同的鎖，需要不同的鑰匙。 |
When a question asks 'explain the mechanism' or 'compare drug classes', pick one or two threads and run a named drug through them. For example: salbutamol = Thread 4 (β2 lock in the lung) + Thread 3 (inhaled delivery avoids systemic side effects). Phenobarbital = Thread 1 (amplifies GABA brake) + Thread 3 (crosses the BBB). This is more memorable than a list of isolated facts and gives your answer a clear causal arc.
當題目問『解釋機制』或『比較藥物類別』時，挑一兩條主線，把一個具名藥物放進去跑。例如：salbutamol = 主線四（肺部的 β2 鎖）＋主線三（吸入給藥避開全身副作用）。Phenobarbital = 主線一（放大 GABA 剎車）＋主線三（穿過 BBB）。這比死背零散事實更容易記，也讓答案有清晰的因果弧線。
Drugs are not isolated facts. They are answers to the same few questions: brake or gas? which side of the seesaw? how does it cross the barrier? which lock is it meant to open?