Pharmacy definitions

35 pharmacy terms from Achievable exam prep courses, each defined in plain language with links into the course textbook.

• ADHD medicationsADHD medications are drugs used to treat attention-deficit/hyperactivity disorder, led by stimulants such as methylphenidate and amphetamine salts, with non-stimulant options including atomoxetine, guanfacine, and clonidine.
• Agonists and antagonistsAn agonist is a drug that binds to a receptor and activates it, mimicking the body's natural signaling molecule. An antagonist binds the same receptor but produces no response, blocking the natural molecule from acting.
• Anti-neoplastic drugsAnti-neoplastic drugs are medications used to treat cancer by killing malignant cells or stopping them from dividing. They include alkylating agents, antimetabolites, antitumor antibiotics, mitotic inhibitors, hormonal agents, and targeted therapies.
• AntiarrhythmicsAntiarrhythmics are medications that treat abnormal heart rhythms by altering the electrical activity of cardiac cells. The Vaughan-Williams system groups them into four main classes: sodium channel blockers, beta blockers, potassium channel blockers, and calcium channel blockers.
• AntibioticsAntibiotics are medications that kill bacteria or stop their growth, used to treat bacterial infections. Major classes include penicillins, cephalosporins, macrolides, tetracyclines, fluoroquinolones, and sulfonamides, each attacking a different bacterial target.
• AnticoagulantsAnticoagulants are medications that interfere with the clotting cascade to prevent blood clots from forming or growing. Major examples include heparin, warfarin, and direct oral anticoagulants like apixaban and rivaroxaban.
• Antidiabetic drugsAntidiabetic drugs are medications that lower blood glucose in diabetes mellitus. They include insulin and non-insulin agents such as metformin, sulfonylureas, GLP-1 receptor agonists, SGLT2 inhibitors, DPP-4 inhibitors, and thiazolidinediones.
• AntiepilepticsAntiepileptics are medications that prevent or reduce seizures by dampening abnormal electrical activity in the brain. They work mainly by blocking sodium or calcium channels, enhancing GABA inhibition, or reducing glutamate excitation.
• AntifungalsAntifungals are drugs that kill or inhibit fungi, working mainly by disrupting ergosterol in the fungal cell membrane or by blocking synthesis of the fungal cell wall. The major classes are the polyenes, azoles, echinocandins, allylamines, and the nucleoside analog flucytosine.
• AntihypertensivesAntihypertensives are medications that lower blood pressure to reduce the risk of stroke, heart attack, heart failure, and kidney disease. The major classes include diuretics, ACE inhibitors, angiotensin receptor blockers, calcium channel blockers, and beta blockers.
• AntipsychoticsAntipsychotics are medications that reduce psychotic symptoms such as hallucinations and delusions, primarily by blocking dopamine D2 receptors in the brain. They are grouped into first-generation (typical) and second-generation (atypical) agents.
• AntiviralsAntivirals are medications that inhibit the replication of viruses inside host cells. Unlike antibiotics, they generally suppress viral reproduction rather than destroying the virus outright, so they work best when started early in an infection.
• AnxiolyticsAnxiolytics are medications used to reduce anxiety. The class includes benzodiazepines, buspirone, certain antidepressants, and sedating antihistamines, and it overlaps closely with sedatives and hypnotics, which are often the same drugs at higher doses.
• ContraindicationA contraindication is a condition or factor that makes a particular medication, treatment, or procedure inadvisable because it could harm the patient. Contraindications may be absolute (never use) or relative (use with caution).
• DEA drug schedulesThe DEA drug schedules are five categories established by the Controlled Substances Act that rank drugs by abuse potential and accepted medical use. Schedule I has the highest abuse potential with no accepted medical use, and Schedule V has the lowest.
• Dosage formsA dosage form is the physical form in which a medication is manufactured and dispensed — tablet, capsule, solution, suspension, ointment, patch, injection, and so on. The dosage form determines how a drug is administered and how quickly it is absorbed.
• Dose vs. dosageA dose is the specific amount of medication taken at one time, such as 500 mg. Dosage is the complete regimen — the dose plus how often and how long it is taken, such as 500 mg twice daily for 10 days.
• Drug interactionsA drug interaction occurs when one substance changes the effect of another, making it stronger, weaker, or more toxic. Interactions may involve two medications, or a medication and a food, supplement, or disease state.
• Drug stabilityDrug stability is the extent to which a medication retains its identity, strength, quality, and purity through storage and use. It determines expiration dating, beyond-use dating, and the storage conditions printed on every prescription label.
• DUR reject errorA DUR reject error is an insurance claim rejection triggered by a drug utilization review — the payer's automated safety screen flags a potential problem, such as a drug interaction or early refill, that must be reviewed before the claim can process.
• Enteral vs. parenteral routesEnteral routes deliver medication through the gastrointestinal tract — oral, sublingual, buccal, rectal, and feeding tube — while parenteral routes bypass the GI tract entirely, most commonly by injection (intravenous, intramuscular, subcutaneous, intradermal).
• Generic vs. brand-name drugsA brand-name drug is the original product marketed under a manufacturer's trademarked name, while a generic is a later copy containing the same active ingredient in the same strength, dosage form, and route. Generics must prove bioequivalence to the brand before the FDA approves them.
• Highly active antiretroviral therapy (HAART)Highly active antiretroviral therapy is the treatment of HIV with a combination of at least three antiretroviral drugs from two or more classes taken together. Combining agents suppresses viral replication far more durably than any single drug and sharply reduces the emergence of resistance.
• Narrow therapeutic index (NTI) medicationsNarrow therapeutic index medications are drugs whose effective dose is very close to the dose that causes toxicity. Small changes in dose, formulation, or absorption can push a patient from therapeutic benefit into harm, so these drugs require careful monitoring.
• Non-sterile compoundingNon-sterile compounding is the preparation of medications that do not have to be sterile — capsules, creams, ointments, suspensions, and suppositories — by combining or altering ingredients for an individual patient. It is governed by USP General Chapter <795>.
• Opioid allergyAn opioid allergy is an immune-mediated hypersensitivity reaction to opioid medications such as morphine or codeine. True opioid allergies are rare — most reported reactions are pseudoallergies caused by direct histamine release rather than the immune system.
• Pharmaceutical incompatibilitiesPharmaceutical incompatibilities are undesirable interactions that occur when drugs or ingredients are combined, making a preparation unsafe or ineffective. They are classified as physical, chemical, or therapeutic incompatibilities.
• PharmacodynamicsPharmacodynamics is the study of what a drug does to the body — how it binds receptors and produces its therapeutic and adverse effects. It complements pharmacokinetics, which describes what the body does to the drug.
• PharmacokineticsPharmacokinetics is the study of what the body does to a drug — how it is absorbed, distributed, metabolized, and excreted (ADME). It determines how much drug reaches its target and how long it stays in the body.
• Phases of drug approvalThe phases of drug approval are the sequential clinical trials — Phase I through Phase IV — a candidate drug must pass before and after FDA approval. Each phase enrolls more participants and answers a different question, moving from safety to efficacy to long-term surveillance.
• Physical incompatibility (pharmacy)Physical incompatibility occurs when two or more drugs or ingredients mixed together produce a visible physical change — such as precipitation, cloudiness, color change, or separation — without necessarily reacting chemically.
• Routes of administrationRoutes of administration are the pathways by which a drug enters the body, such as oral, sublingual, rectal, intravenous, intramuscular, subcutaneous, topical, transdermal, and inhalation. The route affects how fast and how completely the drug works.
• Sig codesSig codes are the abbreviations prescribers use to write medication directions on prescriptions. "Sig" comes from the Latin signa, meaning "write" or "label" — the sig tells the pharmacy what directions to print for the patient.
• StatinsStatins are cholesterol-lowering drugs that inhibit HMG-CoA reductase, the rate-limiting enzyme of cholesterol synthesis. Drugs in the class end in "-statin," such as atorvastatin and simvastatin — lisinopril, an ACE inhibitor, is not a statin.
• Vaccine types and schedulesVaccine types are the different technologies used to trigger protective immunity — live attenuated, inactivated, subunit, toxoid, conjugate, and mRNA — while schedules define the recommended ages, doses, and intervals for each vaccine.