101 Pharmacology Facts Every Pharmacy Student Should Know!

Whilst it’s impossible to summarize all pharmacology facts, this list goes some way toward that goal. We’ve compiled 101 facts that every pharmacy student should know – pharmacology facts that touch indications, mechanisms of action, side effects, drug interactions and other clinical factors; a great addition to NAPLEX revision, NCLEX revision or your next general or clinical pharmacology exam.

1. Amoxicillin is typically the first-line agent in the treatment of otitis media (inflammation of the middle ear).
2. Lamotrigine, a drug used in the treatment of epilepsy and bipolar disorder, has the propensity to cause skin rash. In some cases, this can lead to the potentially fatal Stevens-Johnson syndrome or toxic epidermal necrolysis. Skin rash, then, needs to be monitored closely in these patients.
3. Olanzapine, an atypical antipsychotic drug used in the treatment of schizophrenia and bipolar disorder, has the potential to cause substantial weight gain. It is also known to disfigure blood sugar and lipid profiles.
4. Dehydration can elevate lithium levels to dangerous levels. Lithium is also associated with kidney injury and thyroid imbalances – closely monitoring is required in such cases.
5. Clavulanic acid is a beta-lactamase inhibitor, meaning it inhibits the enzyme responsible for breaking down antibiotics that contain a beta-lactam ring.
6. The broad-spectrum antibacterial, imipenem, is always co-administered with cilastatin. This is because imipenem, if administered on its own, is rapidly degraded by the renal enzyme dehydropeptidase 1; degradation that cilastatin helps to prevent.
7. Metoclopramide has the potential to cause movement disorders, particularly in patients under the age of 20, at high doses, or for those on prolonged therapy.
8. A eugeroic drug is a medicine that promotes wakefulness, an example of which is modafinil – a drug used in the treatment of narcolepsy, shift work sleep disorder and excessive daytime sleepiness.
9. Second-generation antihistamines – such as fexofenadine, acrivastine, cetirizine and loratadine – cause less sedation than their first-generation equivalents, not least due to less penetration through the blood-brain barrier. These medicines are used in the treatment of allergy and hay fever.
10. Triptans are used in the treatment of migraine and cluster headaches. They work by agonising the serotonin receptors, 5-HT_1B and 5-HT_1D – examples of which include sumatriptan and zolmitriptan.
11. There are two major classes of medicines used to treat Alzheimer’s disease – anticholinesterases and NMDA receptor antagonists. Anticholinesterases include donepezil, rivastigmine and galantamine; and our sole NMDA receptor antagonist is memantine. Memantine is often given alongside an anticholinesterase drug.
12. Cilostazol is used in the treatment of intermittent claudication; a condition characterised by muscle pain on mild walking and/or exercise and subsequently relieved by rest. It works by inhibiting phosphodiesterase 3.
13. ACE inhibitors are known to cause a persistent, dry cough – thought by some to be caused by the accumulation of kinins in the lung. Patients are sometimes then switched to angiotensin receptor blockers (ARBs) – though cough may persist.
14. Tizanidine, an α₂ receptor agonist, is a short-acting muscle relaxant used to treat spasms and cramps caused by a variety of disorders. It has been linked to elevated liver enzymes and/or liver damage. It is contraindicated for use with CYP1A2 inhibitors (fluvoxamine, amiodarone, verapamil, oral contraceptives, cimetidine) and with fluoroquinolones, such as ciprofloxacin.
15. Paracetamol overdose causes depletion of glutathione, the compound responsible for ejecting toxic NAPQI. Acetylcysteine can be administered to replenish glutathione levels.
16. Aspirin increases the risk of bleeding. This risk increases in those who are older, who drink alcohol, and who take other NSAIDs and/or blood thinners. Aspirin should be avoided in younger patients as it can cause the potentially fatal Reye syndrome.
17. Drugs with anticholinergic properties (such as atropine and diphenhydramine) are associated with their own distinct range of potential side effects. These include blurred vision, constipation, dizziness, decreased sweating, dry mouth and difficulty urinating.
18. Orlistat is a drug used in the treatment of obesity. It prevents fats from being absorbed (it is a lipase inhibitor). Orlistat is well-known for its gastrointestinal side effect profile, which includes steatorrhea (oily stools), flatulence, and fecal incontinence – side effects which subside with time.
19. Atomoxetine is used in the treatment of attention-deficit hyperactivity disorder (ADHD). It works by inhibiting norepinephrine and serotonin transporters. Side effects include trouble sleeping, dry mouth, cough, decreased appetite, nausea, dizziness and drowsiness.
20. Bisphosphonates – such as alendronate and risedronate – are drugs used to treat osteoporosis and other bone disorders. They work by encouraging osteoclasts (bone-destroying cells) to undergo apoptosis. Oral bisphosphonates should be taken in the morning, 30 minutes before food or other medicines, and with a full glass of water.
21. Statins (lipid lowering medicines) are associated with an increased risk of myopathies (muscle damage/pain) and, in some cases, can lead to the potentially fatal rhabdomyolysis.
22. Buprenorphine is used to treat different conditions at different doses. At lower doses the medicine can be used for chronic pain, whereas at higher doses the medicine is used to treat opioid addiction. It is a partial opioid receptor agonist.
23. Proton pump inhibitors inhibit the terminal step in stomach acid production, by irreversibly blocking the H⁺/K⁺-ATPase of gastric parietal cells. Examples of PPIs include esomeprazole, lansoprazole and pantoprazole.
24. H₂ receptor antagonists also inhibit acid production, though not at the terminal phase. Famotidine and ranitidine are longer-acting than cimetidine, with fewer adverse effects and fewer drug interactions.
25. Mouth washing after inhaled corticosteroid use is important, because this action helps to prevent local adverse effects such as hoarseness and thrush.
26. Tetracycline antibacterials are associated with tooth discolouration (including in the fetus) and phototoxicity. Tetracycline absorption is impaired by drugs or foods containing magnesium, calcium, iron or aluminium ions.
27. Daptomycin is a lipopeptide antibacterial that only treats Gram-positive infections. It is therefore used to treat skin and skin structure infections. Daptomycin is only administered via the intravenous route. It works by disrupting cell membrane function.
28. Ketorolac is an NSAID used in the treatment of moderate-to-severe pain. Due to its side effect profile, ketorolac is only used short-term for around 5-days or less.
29. Beta blockers are avoided in asthmatic patients as they have the potential to precipitate acute asthmatic attacks.
30. Ziprasidone, an atypical antipsychotic, should be taken with food to enhance bioavailability. Failure to do so results in loss of bioavailability by about half.
31. Protamine sulfate is used as an antidote to heparin overdose/toxicity.
32. A nootropic drug is a medicine that enhances cognitive function – an example of which is methylphenidate (a drug used to treat ADHD and narcolepsy).
33. Ethosuximide is an anticonvulsant drug used to treat absence seizures. It is not used to treat other types of seizure such as tonic-clonic, partial or myoclonic.
34. Not all antihypertensive drugs are safe in pregnancy. Methyldopa, nifedipine and labetalol are, however, three examples of drugs that can be used to treat hypertensive states during pregnancy.
35. Fluoroquinolones, a class of antibacterial drugs, are associated with an increased risk of tendon damage. Examples include ciprofloxacin and moxifloxacin.
36. Aminoglycosides, another class of antibacterial drugs, are associated with ototoxicity and nephrotoxicity. Examples include gentamicin and tobramycin.
37. Iron supplements are known to cause black stools, which are harmless. They may also cause constipation and, in some cases, also cause diarrhea.
38. Salbutamol (albuterol) is a short-acting β₂-agonist; it therefore acts as a bronchodilator. Side effects include fast heart rate (tachycardia), tremors, headache, dizziness and anxiety.
39. Constipation is a common side effect of opioid analgesics – such as codeine, morphine and oxycodone – particularly if the patient is taking the medicine long-term.
40. Phosphate binders are often necessary in patients with chronic kidney disease, whose levels of phosphate can rise inextricably. Examples of phosphate binders include sevelamer, lanthanum and calcium acetate.
41. Long-term use and high dosing of metformin, the first-line drug in the treatment of type 2 diabetes, is linked to vitamin B₁₂ malabsorption and its subsequent deficiency.
42. Opioids – such as fentanyl, morphine, heroin and oxycodone – stimulate the parasympathetic nervous system, causing constricted pinpoint pupils. This is a common identifier of opioid toxicity.
43. Pramipexole is a dopamine agonist used in the treatment of Parkinson’s disease symptoms and restless legs syndrome.
44. Iron supplements interact with many medicines. Oral contraceptives can, for example, increase iron levels whereas other medicines, such as proton pump inhibitors and H₂ receptor antagonists, can decrease iron absorption. Iron supplements decrease the absorption of levothyroxine, quinolones, tetracyclines and ACE inhibitors.
45. Felbamate is used in the treatment of partial seizures and Lennox-Gastaut syndrome. It is seldom used these days, though, as it’s associated with aplastic anemia and liver failure.
46. Calcitonin is used to treat osteoporosis in women who are at least 5 years past menopause.
47. Megestrol is used as an appetite stimulant, thereby helping patients to gain weight. This may be necessary in patients with AIDS or who are receiving cancer chemotherapy (‘cachexia’ – wasting syndrome). Megestrol is also used in the treatment of breast and endometrial cancer.
48. An abortifacient is a medicine that induces abortion. Drugs used in a clinical capacity for this role include misoprostol and mifepristone. Methotrexate is sometimes also used for this purpose.
49. Glycine is one of the main inhibitory neurotransmitters of the central nervous system. Glutamate, on the other hand, is one of the principal excitatory neurotransmitters of the CNS (‘i’ for inhibitory in glycine; ‘t’ for excitatory in the word glutamate).
50. Methotrexate is an antifolate drug used in the treatment of various cancers and autoimmune disorders. As an antifolate drug, it can cause folate deficiency. It also works as an immunosuppressant. Side effects include fatigue, nausea, hair loss, leukopenia, ulcerative stomatitis and hepatotoxicity. It is teratogenic.
51. Antidotes are remedies used to counter the effects of toxicity. For example, flumazenil is used for benzodiazepine toxicity; glucagon for beta blocker poisoning; physostigmine for anticholinergic poisoning; phytomenadione (vitamin K) for warfarin poisoning; and deferoxamine for iron poisoning.
52. Drugs with a narrow therapeutic window need close monitoring, as small adjustments in dose can have serious clinical consequences. Examples of drugs with a narrow therapeutic index include warfarin, lithium and digoxin.
53. Spironolactone is a potassium-sparing diuretic. It takes several days to take effect, because its mechanism of action – that of inhibiting the effects of aldosterone by displacing it at mineralocorticoid receptors at the cortical collecting duct – involves nuclear receptors (gene transcription effects etc.). Side effects include hyperkalemia, impotence, breast enlargement, nausea, rash, menstrual disturbances and urinary frequency.
54. Vancomycin is a glycopeptide antibiotic that disrupts production of the bacterial cell wall. It can cause ‘red man syndrome’, a condition that often results if the medicine is administered too quickly. The syndrome is characterised by an upper body rash and facial flushing.
55. There are short and long-acting insulin analogues. Short-acting analogues include insulin aspart, insulin glulisine and insulin lispro. Long-acting analogues include insulin glargine and insulin detemir. Insulin degludec is an ultra-long-acting insulin analogue.
56. Clofazimine, a drug used in the treatment of leprosy, is known to cause brown-pink discolouration of skin in most patients after a few weeks of use. This discolouration can take weeks or months to subside, even after discontinuation of the medicine.
57. Naproxen, an NSAID used in the treatment of pain and inflammation, is associated with an intermediate risk of stomach ulceration, compared to low-risk ibuprofen and high-risk indomethacin.
58. Hydroxychloroquine – an antimalarial drug also used to treat symptoms of rheumatoid arthritis – is associated with eye toxicity, particularly with chronic use. Patients are therefore frequently monitored for the presence of any ocular damage.
59. Loperamide is a mu-opioid receptor agonist used in the treatment of diarrhea. It is not recommended, however, in patients with high fever and/or blood in their stools. Constipation is a relatively common side effect.
60. Isoniazid is used in the treatment of tuberculosis, often in combination with other drugs. Side effects include peripheral neuropathy, elevated liver enzymes, reduced blood cell counts and pyridoxine deficiency (due to higher excretion of pyridoxine).
61. Permethrin is a medicine available for topical use in the treatment of head lice and scabies. Side effects include mild skin irritation and burning. It works to paralyze the pest’s nervous system.
62. Penicillamine is a chelating agent used in the treatment of Wilson’s disease (excess copper in the bloodstream). Penicillamine is also used to chelate cystine in patients with cystinurea (predisposing the patient to cystine stones). Side effects include bone marrow suppression, taste distortion, anorexia, vomiting and diarrhea.
63. Senna is a drug used in the treatment of constipation. It is recommended to be taken at bedtime because it takes 6-12 hours to take effect.
64. Budesonide is a corticosteroid used in the treatment of asthma, COPD and Crohn’s disease. It is contraindicated for use in status asthmaticus (acute asthmatic attack); it is only used in the chronic, long-term treatment of asthma and COPD.
65. Phenylephrine is an α₁-receptor agonist used as a decongestant. Side effects include elevated blood pressure. Pseudoephedrine is also a decongestant that acts through similar means.
66. Sexual dysfunction is a side effect of many medicines. These include SSRIs and SNRIs, as well as some diuretics (hydrochlorothiazide), some beta blockers (propranolol), and diphenhydramine.
67. Sertraline, an SSRI, is associated with greater incidence of psychiatric side effects and diarrhea when compared to other SSRIs. Like other SSRIs, sertraline is also associated with sexual dysfunction.
68. Antibiotics can cause an imbalance in the colonic microbiota. This can lead to the overgrowth of certain bacteria, such as Clostridium difficile. difficile colitis is most associated with clindamycin, fluoroquinolone and cephalosporin use.
69. Furosemide is a loop diuretic used to treat edema (fluid build-up) in congestive heart failure, liver disease and kidney disease. Side effects with furosemide include increased urination, hyperglycemia, ototoxicity (disputed), hypokalemia, hyperuricemia, and hypotension.
70. Steroid medicines, such as prednisolone and dexamethasone, can cause hyperglycemia, particularly with prolonged use – referred to as steroid-induced diabetes. This is because glucocorticoids stimulate gluconeogenesis and oppose the effects of insulin.
71. Benzodiazepines are often classified in terms of their elimination half-life. Short-acting benzodiazepines include alprazolam, oxazepam, midazolam and triazolam. Intermediate-acting drugs include flunitrazepam, clonazepam, lorazepam and temazepam. Long-acting benzodiazepines include diazepam, clorazepate, chlordiazepoxide and flurazepam.
72. Ritonavir a protease inhibitor used in the treatment of HIV. The drug is not typically used for its inherent antiviral activity, but rather as a ‘booster’ for other protease inhibitors. This means that a lower dose of other protease inhibitors is permitted, meaning less adverse effects for affected patients.
73. Protease inhibitors are also linked to HIV-associated lipodystrophy; a condition that leads to fat loss in the face, buttocks, arms and legs; but a redistribution of fat toward other parts of the body, such as the upper back (so-called ‘buffalo hump’).
74. Rifampicin is an antibacterial drug used in the treatment of tuberculosis, leprosy and Legionnaire’s disease; it is known to cause bodily fluids – such as tears, sweat and urine – an orange-red color. This is a benign, harmless side effect.
75. Interferon beta-1a is used in the treatment of multiple sclerosis. While the drug is not a cure for the disease, it does reduce the number of flare-ups. It works by dampening the immune system, specifically by reducing production of Th17 cells; a type of T-lymphocyte.
76. Gingival enlargement is linked to several drug and drug classes. These include the immunosuppressant drug ciclosporin, calcium channel blockers – such as nifedipine, amlodipine and verapamil – and anticonvulsants such as phenytoin, lamotrigine, ethosuximide and topiramate.
77. Finasteride is a 5α-reductase inhibitor used in the treatment of benign prostatic hyperplasia (BPH) and androgenic alopecia. It can take weeks, if not months, to take effect for BPH. Erectile dysfunction is a potential side effect.
78. Patients taking MAO inhibitors need to avoid tyramine in their diets. Failure to avoid tyramine may result in the potentially fatal hypertensive crisis. Tyramine is found in foods such as alcoholic drinks, aged cheeses and meats, liver, chocolate and most other fermented foods.
79. Nitrofurantoin is an antibacterial drug used in the treatment of bladder infections. It also has the potential to discolour urine brown, though this is harmless. It works by damaging bacteria DNA.
80. 5-HT₃ antagonists (often referred to as ‘setrons’) are used in the treatment and prevention of nausea and vomiting – particularly effective in treating nausea and vomiting caused by chemotherapy. Examples include ondansetron, granisetron and palonosetron.
81. Allopurinol is a xanthine oxidase inhibitor used in the treatment of gout and hyperuricemia. It has the potential, more so than many other drugs, to cause the potentially fatal Stevens-Johnson syndrome and toxic epidermal necrolysis. It can also suppress bone marrow, leading to conditions such as aplastic anemia.
82. Fludrocortisone is a synthetic glucocorticoid with predominant mineralocorticoid activity. This means that the drug works to replace the natural hormone, aldosterone. As such, fludrocortisone is used to treat Addison’s disease (a condition where the adrenal glands insufficiently produce enough steroid hormones).
83. Fusidic acid is used in the treatment of skin infections. As such, the drug only has activity against Gram-positive organisms.
84. Both gabapentin and pregabalin are used to treat nerve pain and seizures; the precise mechanism of which is not yet fully understood. Gabapentin is also used to treat restless legs syndrome and anxiety disorders.
85. Cold sores are caused by the herpes simplex virus. Various treatments exist, one of them being docosonal topical; a drug that shortens healing time and the length of time symptoms remain. However, it works best when applied in the earlier stages of the cold sore infection.
86. Calamine – either a blend of zinc oxide with ferric oxide, or else a zinc carbonate compound – is a drug used in a lotion to treat itch, sunburn, rash, chickenpox and insect bites/stings.
87. Gastroparesis – referring to delayed gastric emptying – often develops in diabetic patients; the condition being caused by damage to the vagus nerve. Anticholinergic medicines – such as diphenhydramine – can exacerbate this problem.
88. Symptoms of iron deficiency include fatigue, dizziness, hair loss, irritability, impaired immune function and restless legs syndrome. Pagophagia, the compulsive desire to consume ice/iced drinks, has also been linked to iron deficiency anemia. Iron supplements have also been shown to reduce this desire.
89. Propofol is a short-acting anaesthetic – used to commence and maintain general anaesthesia, sedation in mechanically ventilated patients, and in procedural sedation. It is administered intravenously and takes 2 minutes to reach maximum effect. It works by potentiating GABA_A activity and by blocking sodium channels.
90. The following drugs are used as intestinal antihelminthics – albendazole, levamisole, mebendazole, niclosamide, praziquantel and pyrantel.
91. Sofosbuvir is used in the treatment of hepatitis C; a drug with a higher cure rate and one associated with less side effects when compared to other hepatitis C drugs, such as peginterferon. It is often combined with other drugs, such as ledipasvir; though combined sofosbuvir medicines should not be administered with amiodarone due to the risk of abnormally slow heartbeats (bradycardia). It works by inhibiting the hepatitis C protein, NS5B.
92. Betamethasone is a steroid medicine used to treat rheumatic disorders, psoriasis, and allergic conditions. It is also used to stimulate fetal lung maturity in preterm labor.
93. Antitussive drugs are medicines used to suppress cough, examples of which include codeine, pholcodine and dextromethorphan.
94. Orexigenic drugs are drugs that stimulate appetite, examples of which include olanzapine, prednisolone, haloperidol and sulphonylureas.
95. Azole antifungal drugs – such as ketoconazole, clotrimazole and fluconazole – work by inhibiting the enzyme, lanosterol-14α-demethylase, the enzyme responsible for converting lanosterol into ergosterol. Ergosterol is needed for the structural integrity of the cell membranes of fungi.
96. Extrapyramidal symptoms include dystonia (spasms/muscle contractions), akathisia (motor restlessness), Parkinsonism (rigidity), tardive dyskinesia (jerky, irregular movements) and tremor. Extrapyramidal symptoms are caused by typical antipsychotic drugs (eg. haloperidol) that antagonise the D2 receptor subtype. Other drugs, such as metoclopramide and antidepressants (long-term), can also cause these symptoms.
97. Domperidone is a selective D2 receptor antagonist. It’s used as an antiemetic and gastroprokinetic agent. Other gastroprokinetic agents include erythromycin and metoclopramide.
98. There are two main types of heparin: unfractionated heparin and low molecular weight heparin (LMWH). Examples of the latter include enoxaparin and dalteparin. They are anticoagulant medicines used to treat and prevent DVT, pulmonary embolism and arterial thromboembolism. Potential side effects include injection site pain, bleeding and thrombocytopenia.
99. Warfarin is an anticoagulant drug that works by inhibiting the vitamin K-dependent synthesis of clotting factors II, VII, IX and X. Risk of clotting increases during initial phase of therapy due to a variety of bodily adjustment effects.
100. There are three main drugs used in the treatment of alcoholism. These include disulfiram, acamprosate, and naltrexone. Disulfiram prevents the removal of the toxic acetaldehyde, meaning the patient experiences severe effects when more alcohol is consumed. Diarrhea is the most common side effect of acamprosate. Naltrexone works by decreasing cravings for alcohol.
101. Bevacizumab is an angiogenesis inhibitor, meaning that it slows the growth of new blood vessels. It blocks angiogenesis by inhibiting vascular endothelial growth factor A (VEGF-A). It is used to treat various types of cancer – such as colon cancer, lung cancer, renal cancers and glioblastoma multiforme.