RRB Pharmacist Recruitment Exam key terms

The study of how the body handles a drug over time, covering absorption into blood, distribution to tissues, metabolism mainly in the liver, and excretion mainly by the kidney. It links dose given to concentration achieved.

The fraction of an administered dose that reaches systemic circulation unchanged. Intravenous dosing is taken as 100 percent by definition; oral values are lower because of incomplete absorption and first-pass liver metabolism.

Breakdown of an orally swallowed drug in gut wall and liver before it enters general circulation, reducing the amount that survives. It explains why some drugs need much larger oral than intravenous doses, or are given by another route.

The time needed for the plasma concentration of a drug to fall by half during elimination. It guides dosing interval, predicts how long effects last, and shows roughly how many doses are needed to reach steady state.

The condition in which drug entering the body per dose equals drug being eliminated, so plasma levels fluctuate around a stable average. It is usually approached after about four to five elimination half-lives of regular dosing.

A ratio comparing the dose producing toxicity with the dose producing the desired effect. A narrow index, as with digoxin or lithium, means small changes in blood level can cause harm, so monitoring and careful dosing are needed.

An agonist binds a receptor and activates it to produce a response. An antagonist binds without activating and blocks the agonist, reducing or preventing effect. The pair explains much of how drugs act at receptors.

Potency describes how little drug is needed for a given effect, shown by a lower effective dose. Efficacy describes the largest effect a drug can produce. A drug can be very potent yet have low maximum efficacy.

A harmful or unintended response to a medicine used at normal doses. Reactions may be predictable and dose-related, or unpredictable and immune-mediated. Serious ones must be reported to the national pharmacovigilance programme.

The science of detecting, assessing, understanding and preventing adverse effects or any other drug-related problem after medicines are marketed. In India it runs through the Pharmacovigilance Programme of India and its adverse drug reaction monitoring centres.

An inactive chemical form of a drug that the body converts into the active agent, usually by liver enzymes. The design improves absorption, stability or targeting; a well-known example is enalapril becoming enalaprilat.

A protein molecule, often on a cell surface or inside the cell, that binds a drug or natural messenger specifically and triggers a biological response. Receptor type determines which drugs work and which side effects appear.

The demonstration that two products of the same drug reach the bloodstream at comparable rate and extent, usually judged by peak concentration and total exposure within accepted limits. It is the basis for approving generic copies.

A polymer film on a tablet or capsule that resists stomach acid and dissolves in the more alkaline intestine. It protects acid-labile drugs and irritant drugs, and prevents premature release that could harm gastric mucosa.

A dosage design that liberates drug gradually over hours rather than at once, keeping blood levels steadier and reducing dose frequency. Such products must not be crushed or chewed unless the label permits it.

Any inactive ingredient added to a formulation, such as diluent, binder, disintegrant, lubricant, preservative, colour or flavour. Excipients aid manufacture, stability and patient acceptability, and some can cause allergy or intolerance.

Water for injection prepared by distillation or reverse osmosis, sterilised and free of fever-producing bacterial fragments. It is the vehicle for parenteral products; ordinary purified water is not acceptable for injections.

Equipment that sterilises by saturated steam under pressure, commonly at 121 degrees Celsius for 15 to 20 minutes. Trapped air must be removed so steam contacts every surface; it suits heat-stable and moisture-tolerant items.

A chemical agent applied to inanimate surfaces to destroy or inhibit disease-causing organisms. It is generally too irritant for living tissue, unlike an antiseptic, and its activity depends on concentration, contact time and organic matter.

Any route of administration that bypasses the digestive tract, such as intravenous, intramuscular, subcutaneous or intradermal injection. Parenteral products must be sterile and free from particles and pyrogens.

An official book of drug standards, including identity, purity, strength and test methods. The Indian Pharmacopoeia is recognised under the Drugs and Cosmetics Act, and a drug must comply with its monograph when one exists.

A category under the Drugs and Cosmetics Rules listing prescription-only medicines that must be sold on the written prescription of a registered medical practitioner. The container carries the warning symbol and label text required by the schedule.

A tightly controlled class of medicines, such as certain narcotics and psychotropics, requiring special licences, prescriptions retained by the pharmacy and records kept for inspection. Rules are stricter than for Schedule H products.

The process of removing a batch or product from the market or from distribution when it is defective or unsafe. Recall classes reflect the severity of harm, and pharmacies must cooperate fully and document returned stock.

A written, dated and signed instruction from a registered medical practitioner authorising supply of specified medicines to a named patient. Pharmacists must verify legality, legibility and dose, and clarify doubtful items rather than guess.

Prescribing and dispensing medicines that are appropriate to the patient's clinical need, at correct dose, for adequate duration and at acceptable cost. Irrational use includes unnecessary antibiotics, polypharmacy and excessive injections.

A national list of medicines chosen for safety, efficacy, cost and public health need, used to guide procurement and supply in government health facilities. India publishes a National List of Essential Medicines that is periodically revised.

The study of crude drugs and medicinal substances obtained from plants, animals, microbes and minerals, covering their source, cultivation, collection, identification, chemistry and standardisation. It underpins quality control of herbal medicines.

A naturally occurring nitrogen-containing basic compound found mainly in plants, often strongly active on the body. Examples include morphine, quinine, atropine and caffeine; most are extracted and assayed as their salts.

The set of tests and specifications used to confirm that a herbal or natural product has consistent identity, purity and active content, such as marker assays, ash value and moisture. It protects against adulteration and batch-to-batch variation.

The existence of molecules with the same atoms bonded in the same order but arranged differently in space, giving enantiomers and diastereomers with distinct physical and biological properties. Many drugs act differently as one isomer.

pH expresses acidity as the negative logarithm of hydrogen ion concentration. A buffer resists pH change when acid or alkali is added. Both govern drug solubility, stability, absorption and the performance of injections and eye drops.

The body's tendency to keep internal conditions such as temperature, pH, blood glucose and water balance within narrow limits using feedback control. Disease often reflects disturbed homeostasis, and drugs frequently act by restoring it.

The functional unit of the kidney, comprising a glomerulus and tubule, where blood is filtered and useful substances are reabsorbed. It determines renal drug clearance, so kidney impairment often requires dose reduction.

A protective local response to injury or infection marked by redness, heat, swelling, pain and loss of function. It involves vasodilatation, increased capillary permeability and migration of white cells, and is a target of many drugs.

A protein catalyst that speeds a specific biochemical reaction by lowering its activation energy. Enzymes control metabolism, are measured in blood to detect organ damage, and are inhibited or induced by many drugs.

Laboratory work that exposes an isolated organism to discs or strips carrying antibiotics to determine which drugs inhibit it. Results, reported as sensitive, intermediate or resistant, guide safe and effective therapy and limit resistance.

Recent national and international developments, including government schemes, appointments, sports and science events, that are tested in the general awareness section. Candidates should revise a few months of news before the examination.

The basic freedoms guaranteed to citizens by Part III of the Indian Constitution, including equality, speech, life and liberty, and constitutional remedies. They are enforceable in courts and can be restricted only as the Constitution allows.