Pharmacology Facts Every Pharmacist Should Know

Pharmacology Facts Every Pharmacist Should Know

Pharmacology is a difficult subject for students but we try to make it easy here. Pharmacists working in pharmacy or pharmacy students need to know these pharmacology facts. These facts that touch indications, mechanisms of action, side effects, drug interactions and other clinical factors and also important for Nepal Pharmacy Council (NPC) Licensure Examination for Diploma Phaarmacy and Bachelor of Pharmacy.

Chlorpromazine is approved for the treatment of intractable hiccups. The dose is 25-50 mg orally/ if hiccups persist it can be given IM or slow IV.
ACE inhibitors and Beta-blockers can cause Nasal congestion and Rhinitis
Amiodarone is a class III anti-arrhythmic agent. Standard therapy with 200-mg amiodarone tablet (which contains 75 mg of iodine) can provide more than 100 times the daily iodine.Thyroid dysfunction occurs in up to 20% of patients receiving long-term amiodarone therapy.
Thiazide diuretics decrease urinary calcium excretion;Hence, they are used for prevention/treatment of renal stones associated with hypercalciuria.
Lignocaine (Lidocaine) for local anaesthesia contains methylparaben as a preservative.Hence This preparation should NOT be given for cardiac indications.Cardiac Lignocaine preparations are different from LA preparations being specially formulated without this preservative.
S-amlodipine is less likely to cause ankle edema as compared to Amlodipine.
NSAIDs should be avoided in pregnant women especially in the first and third trimester.Paracetamol is quite safe in pregnant women and can be given for its analgesic and anti-pyretic activity.
Before the corticosteroid prednisone can become active, it needs to be converted by the liver into prednisolone. Therefore, prednisone is an example of a prodrug.
Lactulose reduces ammonia absorption, making it effective in patients with liver failure in whom ammonia plays a major role in the development of hepatic encephalopathy.
Epinephrine is used alongside local anesthetics such as lidocaine to prolong that local anesthetic effect.
Macrolides are irritant to the GI tract, however, erythromycin causes more GI effects compared to other macrolides.
Nitrofurantoin is commonly used to treat UTIs in early pregnancy. However, it is avoided in late pregnancy due to the risk of hemolytic anemia in the newborn and neonatal jaundice.
Ethosuximide is a drug used only in the treatment of absence seizures. It works in part by blockade of T-type calcium channels.
Oral iron salts reduce the absorption of drugs such as levothyroxine, bisphosphonates, and tetracyclines.
Both dexamethasone or betamethasone can be used to promote fetal lung maturation in cases of premature labor.
Amphotericin B, an antifungal drug, is associated with “shake and bake” — violent chills and fever that occur shortly (1-3hrs) after infusion.Other effects include hypotension, nausea, headache, and tachypnea.
Metformin must be withheld before and for 48-hours after injection of IV contrast media – due to the increased risk of renal impairment, metformin accumulation, and lactic acidosis
Patients with renal failure are at an added risk of aluminum toxicity if administered sucralfate.
Trimethoprim is chemically related to the antimalarial drug, pyrimethamine.Both of these drugs are folate antagonists; with both drugs resembling the pteridine moiety of folate itself.This similarity is sufficient to trick bacterial dihydrofolate reductase.
Topiramate is a fructose derivative that is used in the treatment of epilepsy, particularly Lennox-Gastaut syndrome. It can also be used to prevent migraines.It works in part via AMPA-receptor blockade and by inhibiting the enzyme, carbonic anhydrase.
Dopamine is a neurotransmitter as well as being the precursor for noradrenaline.Dopamine is degraded in a similar way to noradrenaline, giving rise mostly to dihydroxyphenylacetic acid and homovanillic acid – both of which are eliminated in the urine.
Clavulanic acid is a beta-lactamase inhibitor, meaning it inhibits the enzyme responsible for breaking down antibiotics that contain a beta-lactam ring.
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.
Paracetamol overdose causes depletion of glutathione, the compound responsible for ejecting toxic NAPQI. Acetylcysteine can be administered to replenish glutathione levels.
Mouth washing after inhaled corticosteroid use is important, because this action helps to prevent local adverse effects such as hoarseness and thrush.
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.
Fluoroquinolones, a class of antibacterial drugs, are associated with an increased risk of tendon damage. Examples include ciprofloxacin and moxifloxacin.
Aminoglycosides, another class of antibacterial drugs, are associated with ototoxicity and nephrotoxicity. Examples include gentamicin and tobramycin.
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.
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.
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.
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.
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.
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.
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.
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.
Fusidic acid is used in the treatment of skin infections. As such, the drug only has activity against Gram-positive organisms.
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.
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.
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.
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.