Pharmacology Reviewer for PLE Philippines 2026

By LisensyaPrep Team | Last Updated: April 2026 | 12-minute read

Pharmacology is the backbone of the Pharmacy Licensure Examination. It connects your chemistry knowledge to actual clinical practice and is the subject where understanding beats memorization every time. If you know why a drug works the way it does, you can answer scenario questions even about drugs you have never specifically studied.

This reviewer covers the essential pharmacology framework and the highest-yield drug categories for the PLE.

Pharmacokinetics: What the Body Does to the Drug

Pharmacokinetics describes how the body handles a drug from the moment it enters until it is eliminated. The four processes are absorption, distribution, metabolism, and excretion. This is the ADME framework and it underlies almost every pharmacokinetics question in the PLE.

Key Pharmacokinetics Concepts

Bioavailability is the fraction of an administered drug that reaches systemic circulation unchanged. Intravenous administration has 100% bioavailability. Oral bioavailability is reduced by first-pass metabolism.

First-pass effect occurs when a drug absorbed from the gastrointestinal tract is metabolized by the liver before reaching systemic circulation. Drugs with high first-pass effects (morphine, lidocaine, propranolol) have much lower oral bioavailability than IV bioavailability.

Half-life (t½) is the time required for the plasma concentration of a drug to decrease by 50%. It determines dosing intervals. After 4 to 5 half-lives, a drug is considered essentially eliminated from the body.

Steady state is reached after approximately 4 to 5 half-lives of repeated dosing. At steady state, the rate of drug input equals the rate of drug elimination.

Volume of distribution (Vd) describes how widely a drug distributes throughout body compartments. A large Vd means the drug distributes extensively into tissues rather than staying in the blood.

Pharmacodynamics: What the Drug Does to the Body

Pharmacodynamics covers the mechanisms by which drugs produce their effects.

Agonist: A drug that binds to a receptor and activates it, producing a biological response.

Antagonist: A drug that binds to a receptor but does not activate it, blocking the response to agonists. Competitive antagonists can be overcome by increasing agonist concentration. Non-competitive antagonists cannot.

Partial agonist: A drug that binds to a receptor and activates it but produces a submaximal response even at full receptor occupancy.

Therapeutic index (TI): The ratio of the toxic dose to the effective dose. A narrow therapeutic index means the difference between the effective dose and the toxic dose is small, requiring careful monitoring. Examples of narrow TI drugs: digoxin, warfarin, lithium, phenytoin, theophylline.

Autonomic Nervous System Drugs

The autonomic nervous system drugs are among the most heavily tested drug categories in PLE pharmacology. Know both the mechanism and the clinical effects.

Cardiovascular Drugs

Antihypertensives

ACE Inhibitors (captopril, enalapril, lisinopril): End in "-pril." Block conversion of angiotensin I to angiotensin II. Key side effect: dry cough (due to bradykinin accumulation). Contraindicated in pregnancy (causes fetal renal damage).

Angiotensin Receptor Blockers (ARBs) (losartan, valsartan): End in "-sartan." Block angiotensin II receptors. Same cardiovascular benefits as ACE inhibitors without the cough. Also contraindicated in pregnancy.

Calcium Channel Blockers: Dihydropyridines (amlodipine, nifedipine) act mainly on vascular smooth muscle causing vasodilation. Non-dihydropyridines (verapamil, diltiazem) also slow heart rate.

Thiazide Diuretics (hydrochlorothiazide): First-line treatment for hypertension. Watch for hypokalemia, hyperuricemia, and hyperglycemia as side effects.

Anticoagulants

Warfarin: Vitamin K antagonist. Narrow therapeutic index. Monitored by INR. Antidote: Vitamin K for minor bleeding, fresh frozen plasma (FFP) for severe bleeding.

Heparin: Activates antithrombin III. Monitored by aPTT. Antidote: protamine sulfate.

Low molecular weight heparins (LMWH) (enoxaparin): More predictable than unfractionated heparin. Given subcutaneously. No routine monitoring needed.

Antidyslipidemics

Statins (atorvastatin, simvastatin): End in "-statin." Inhibit HMG-CoA reductase, reducing cholesterol synthesis. Most effective LDL-lowering agents. Key side effects: myopathy (muscle pain), rhabdomyolysis (rare but serious).

Anti-infective Drugs

Antibiotics by Class

Penicillins (amoxicillin, ampicillin): Beta-lactam antibiotics. Inhibit cell wall synthesis. Major concern: allergic reactions including anaphylaxis. Cross-reactivity with cephalosporins in about 1 to 10% of penicillin-allergic patients.

Cephalosporins (cephalexin, cefuroxime, cefixime): Also beta-lactams. Grouped by generations with increasing gram-negative coverage in higher generations.

Fluoroquinolones (ciprofloxacin, levofloxacin): End in "-floxacin." Inhibit DNA gyrase. Broad-spectrum. Avoid in children and pregnant women (affect cartilage development). Can prolong QT interval.

Macrolides (azithromycin, clarithromycin): End in "-thromycin." Inhibit protein synthesis. Good for atypical pneumonia pathogens.

Tetracyclines (doxycycline, tetracycline): Inhibit protein synthesis. Avoid in children under 8 and pregnant women (discoloration of developing teeth and bones). Take with full glass of water, do not take with dairy or antacids.

Aminoglycosides (gentamicin, amikacin): Narrow therapeutic index. Monitor for nephrotoxicity and ototoxicity. Given parenterally for serious infections.

Common Drug Interactions to Know

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Pharmacology questions in the PLE combine mechanism knowledge with clinical application. The best preparation is practicing scenario questions that ask you to choose the right drug for a patient or identify the cause of a side effect.

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