Free DHA Pharmacist Exam Exam Flashcards

N-acetylcysteine, which replenishes glutathione so the toxic metabolite NAPQI can be conjugated. It is most effective within 8 hours of ingestion, and treatment is guided by the timed serum level plotted on the Rumack-Matthew nomogram. Give it on suspicion rather than waiting for liver enzymes to rise.

Atropine blocks muscarinic effects (bronchial secretions, bradycardia, the SLUDGE picture) but does nothing at nicotinic receptors, so it does not fix muscle weakness or paralysis. Pralidoxime reactivates acetylcholinesterase itself and must be given early, before the enzyme-organophosphate bond ages and becomes irreversible.

It treats the cardiac toxicity, seen as a widening QRS above about 100 ms and ventricular arrhythmia. TCAs block fast sodium channels; the sodium load plus serum alkalinisation reduces drug binding to the channel. The QRS width, not the ingested dose, drives the decision to treat.

The strained four-membered beta-lactam ring acylates the active site of penicillin-binding proteins, halting peptidoglycan cross-linking. Bacterial beta-lactamases hydrolyse that same ring, which is why the drug is paired with an inhibitor such as clavulanic acid, sulbactam or tazobactam that sacrifices itself to protect it.

They are structural analogues of para-aminobenzoic acid and competitively inhibit dihydropteroate synthase, so bacteria cannot synthesise folate. Human cells take up preformed dietary folate and lack that enzyme entirely, which gives the selectivity. Excess PABA at the infection site antagonises the drug.

A prodrug is inactive until metabolised: enalapril needs hepatic esterases to become enalaprilat, valaciclovir becomes aciclovir, codeine needs CYP2D6 to become morphine, and clopidogrel needs CYP2C19. The practical consequence is that impaired metabolism or an enzyme inhibitor causes therapeutic failure rather than toxicity.

A horizontal LAFW blows filtered air out toward the operator, protecting only the product, so it must never be used for cytotoxics. Hazardous and cytotoxic preparation requires a Class II biological safety cabinet or isolator with vertical airflow and external venting, sited in a negative-pressure room to protect the operator.

First air is the air moving directly from the HEPA filter to the critical site before it touches anything. Nothing, including your hands, may sit between the filter and an open vial neck or needle hub. Work at least six inches inside the hood, and disinfect stoppers with sterile 70% isopropyl alcohol and let them dry.

Cocoa butter is an oleaginous base that melts at body temperature, so it needs cool storage and a displacement value correction when calculating drug quantity. PEG bases do not melt; they dissolve in rectal secretions, tolerate warm climates without refrigeration, but draw water and can be irritating, so moistening before insertion is advised.

Class I is high solubility and high permeability, the ideal case. Class II is low solubility and high permeability, so dissolution is rate-limiting and particle size matters. Class III is high solubility and low permeability, limited by absorption across the gut wall. Class IV is low in both and absorbs poorly and erratically.

Dissolution rate rises with effective surface area, the diffusion coefficient and the concentration gradient between the saturated diffusion layer and the bulk, and falls as the diffusion layer thickens. This is why micronising a poorly soluble drug such as griseofulvin, or stirring the medium, increases the dissolution rate.

The coating resists gastric acid and dissolves only at the higher pH of the small intestine, either protecting an acid-labile drug such as omeprazole or protecting the stomach from an irritant such as aspirin. Crushing destroys that barrier, causing drug degradation, gastric injury, or dose dumping of an entire modified-release load at once.

It induces CYP3A4 and P-glycoprotein, lowering plasma levels of combined oral contraceptives, ciclosporin, tacrolimus, warfarin and HIV protease inhibitors, which has caused unintended pregnancy and transplant rejection. Combined with an SSRI it also adds serotonergic risk. Failure appears after a week or two, not immediately.

Ginkgo biloba, garlic, ginger, ginseng and high-dose fish oil all have antiplatelet activity, and vitamin E adds to it. The risk matters most alongside warfarin, aspirin, clopidogrel or a DOAC, and before surgery. Ask about supplements explicitly, because patients rarely list them as medicines.

It irreversibly inhibits intestinal CYP3A4, so more drug survives the gut wall and systemic exposure rises. Simvastatin, felodipine, ciclosporin and some calcium channel blockers are affected, raising the risk of myopathy or hypotension. The effect lasts a day or more, so separating the doses does not solve it.

1:5000 w/v means 1 g in 5000 mL. Percentage strength is grams per 100 mL, so 100/5000 = 0.02% w/v. In mg/mL, 1000 mg divided by 5000 mL = 0.2 mg/mL. Remember the direction: as the ratio denominator grows, the strength falls.

Take the differences diagonally. 70 minus 40 gives 30 parts of the 20% product; 40 minus 20 gives 20 parts of the 70% product. So mix 20 parts of 70% with 30 parts of 20%, a total of 50 parts. Check it: (20 x 70 + 30 x 20) / 50 = 40%.

BSA in m2 is the square root of (height in cm x weight in kg / 3600). For 160 cm and 70 kg: 11200/3600 = 3.11, and the square root is 1.76 m2. A dose of 100 mg/m2 is therefore 176 mg. Cytotoxic and paediatric doses use BSA rather than weight alone.

First find the concentration: 500 mg / 250 mL = 2 mg/mL. Then divide the desired rate by the concentration: 2 mg/min / 2 mg/mL = 1 mL/min, which is 60 mL/h. Always calculate the concentration first, because the pump is set in mL/h while the order is written in mg/min.

Clopidogrel is a prodrug activated largely by CYP2C19. Loss-of-function alleles produce less active metabolite, weaker platelet inhibition and a higher risk of stent thrombosis. Prasugrel and ticagrelor do not depend on CYP2C19 and are the usual alternatives. Omeprazole inhibits the same enzyme and can mimic the phenotype.

Carriers face a high risk of a systemic hypersensitivity reaction, so the allele must be tested before abacavir is ever started and the drug withheld if the result is positive. Once a reaction has occurred, rechallenge is absolutely contraindicated because it can be fatal.

This allele carries a markedly increased risk of Stevens-Johnson syndrome and toxic epidermal necrolysis with carbamazepine, and is most common in people of Han Chinese and other Southeast Asian ancestry. Screening before initiation is recommended in those groups, and a positive result means choosing a different anticonvulsant.

Before touching a patient, before a clean or aseptic procedure, after body fluid exposure risk, after touching a patient, and after touching patient surroundings. Alcohol-based rub is preferred for routine use, but visibly soiled hands and cases of Clostridioides difficile or norovirus need soap and water, because alcohol does not kill those spores or that virus.

Do not recap needles; if recapping is unavoidable use a one-handed scoop. Dispose at the point of use in a rigid, puncture-resistant, labelled container and seal it at the fill line, roughly three-quarters full, since overfilling causes most injuries. The person who used the sharp is the person who disposes of it.

Patients with significant immunosuppression from disease, chemotherapy, high-dose corticosteroids or biologics, and pregnant women. This covers MMR, varicella, zoster, yellow fever, BCG, oral typhoid and live attenuated influenza. Inactivated vaccines are safe in these groups but may produce a weaker response.

About four to five: roughly 94% after four and 97% after five. The same applies to washout after stopping. Half-life depends on both volume of distribution and clearance (t1/2 = 0.693 x Vd / CL), so a change in either alters how long steady state takes.

Vd is the apparent volume relating the dose to the plasma concentration, not a real space. A large Vd, such as digoxin at roughly 6-7 L/kg, means the drug sits mostly in tissue, so haemodialysis removes little of it and a loading dose is needed to fill the compartment quickly.

First-order clears a constant fraction per unit time, so concentration rises in proportion to dose. Zero-order clears a fixed amount because the enzyme is saturated, so a small dose increase causes a disproportionate jump in level. Phenytoin, ethanol and high-dose salicylates behave this way, which is why phenytoin is titrated in small increments.

Bioavailability is the fraction of a dose reaching the systemic circulation, and is 1 for an intravenous dose by definition. Drugs heavily extracted by gut wall and liver on the first pass, such as glyceryl trinitrate, propranolol, morphine and lidocaine, have low oral bioavailability, which is why they are given sublingually, parenterally, or at much larger oral doses.

Hold it around iodinated contrast imaging and in acute illness with dehydration, hypoxia or sepsis, and avoid it when eGFR falls below 30 mL/min/1.73 m2, because the risk is lactic acidosis. It does not cause hypoglycaemia on its own. HbA1c reflects the previous two to three months of control.

Poor control, not an adequate rescue plan. Daily use, or needing about three or more canisters a year, means the inhaled corticosteroid regimen must be stepped up rather than the reliever repeated. Check technique and add a spacer, and remind the patient to rinse the mouth after every steroid dose to prevent oral candidiasis.

A renin-angiotensin blocker (ACE inhibitor, ARB or ARNI), a beta-blocker, a mineralocorticoid receptor antagonist, and an SGLT2 inhibitor. Start the beta-blocker at a low dose only when the patient is euvolaemic, and monitor potassium and renal function after starting or increasing the MRA.

Warfarin needs INR monitoring, usually to a target of 2-3, or 2.5-3.5 for a mechanical mitral valve, and is reversed with vitamin K plus factor concentrate. DOACs need no routine monitoring but do need dose adjustment for renal function, and they must not be used in mechanical valves or moderate-to-severe mitral stenosis.

Insulin, anticoagulants including heparin, concentrated electrolytes especially potassium chloride, opioids, chemotherapy and neuromuscular blockers. They are not the drugs that cause the most errors, but the ones where an error causes severe harm. Concentrated potassium chloride is removed from ward stock and never given by IV push.

Write "units" instead of U and "international units" instead of IU, spell out daily rather than QD, and write out morphine sulfate rather than MS or MSO4. Never use a trailing zero, since 1.0 mg is read as 10 mg, and always use a leading zero, because .5 mg is read as 5 mg.

Capitalising the differing letters breaks the visual similarity, as in predniSONE and predniSOLONE, hydrOXYzine and hydrALAZINE, or DOPamine and DOBUTamine. Pair it with physical separation on the shelf and an independent second check before any high-alert medicine is dispensed or administered.

Digoxin, lithium, phenytoin, warfarin, vancomycin, aminoglycosides and theophylline all need monitoring. Timing decides whether the number means anything: take a trough immediately before the next dose, and sample digoxin at least six hours after the dose, or the distribution phase gives a falsely high result.

Refer a cough lasting more than about three weeks, or with blood in the sputum, unexplained weight loss, breathlessness, chest pain, fever that will not settle, or a suspected drug cause such as an ACE inhibitor. Cough in an infant, or in a patient whose cough changed character, also needs medical assessment.

Combination cold, flu and pain products contain paracetamol that the patient does not count. The adult maximum is 4 g in 24 hours, up to 1 g per dose at least four hours apart. Always ask what else is being taken, and reduce the maximum in low body weight, chronic alcohol use or liver disease.

Levonorgestrel 1.5 mg is licensed within 72 hours and ulipristal acetate 30 mg within 120 hours; both work better the sooner they are taken. Repeat the dose if vomiting occurs within three hours. Efficacy falls at higher body weight, so a copper IUD is the most effective option where available.

Not more than three days from the date the treating physician issued it, and the pharmacist must not dispense it after that. Refills are prohibited, and the pharmacist in charge signs before dispensing. Prescriptions are retained in the facility for at least five years, and each dispensed quantity is entered in the narcotic register book.

A general practitioner or general dentist may prescribe a controlled drug for up to three days, once only for the same diagnosis and treatment. A specialist may prescribe up to 15 days and a consultant up to 30 days, within their scope of specialty. Prescribing goes through the Unified Controlled Medication Platform, and refills are not issued except on an approved exception list.

A general practitioner or general dentist may prescribe up to 30 days with no refill, a specialist up to 30 days plus one 30-day refill, and a consultant up to 30 days plus two 30-day refills. A refill is dispensed only at the end of the previous 30 days. The prescription itself is valid for three days, and records are kept for at least two years.

Narcotic prescribing, dispensing and use are normally confined to hospital inpatient and emergency settings, and only consultants and specialists prescribing within their specialty may order them. The exception is cancer patients, severe pain and the period after major surgery, where tablets, capsules and patches may be supplied for outpatient use for a maximum of 30 days.

A prescription-only medicine prescription is valid for three months, unlike the three-day window for narcotic, controlled and semi-controlled drugs. Adverse drug reactions and medication errors are reported to the DHA Drug Control Section within 15 days using the official reporting forms.

A dry persistent cough comes from bradykinin accumulation and settles on switching to an ARB, which does not raise bradykinin. Angioedema is different: it is a reason never to rechallenge with an ACE inhibitor, and an ARB is used only with caution. Both classes are contraindicated in pregnancy and in bilateral renal artery stenosis.

Simvastatin is a CYP3A4 substrate, so exposure and myopathy risk rise with inhibitors. The dose is capped at 20 mg daily with amlodipine or amiodarone, and at 10 mg daily with verapamil or diltiazem. Avoid it altogether with strong inhibitors such as clarithromycin or itraconazole; pravastatin and rosuvastatin depend far less on CYP3A4.

ACE inhibitors and ARBs, spironolactone and other potassium-sparing diuretics, trimethoprim, NSAIDs, heparin and potassium supplements. The risk is additive, so the danger is the combination rather than any single agent, and it climbs sharply in renal impairment or dehydration. Check potassium and renal function after starting or increasing any of them.

Amiodarone, sotalol, macrolides, fluoroquinolones, ondansetron, many antipsychotics and citalopram all prolong the QT interval and can precipitate torsades de pointes. The risk multiplies when two are combined, and hypokalaemia, hypomagnesaemia and bradycardia are the correctable contributors to check first.

Beta-lactams kill in a time-dependent way, so efficacy tracks the time the concentration stays above the MIC; that favours more frequent doses or extended infusion. Aminoglycosides and fluoroquinolones are concentration-dependent, tracking peak-to-MIC and AUC-to-MIC ratios, which is the rationale for once-daily aminoglycoside dosing.