PH8.1-11 | Antimicrobial and Chemotherapy Pharmacology — Glossary

A synthetic guanosine nucleoside analogue antiviral selectively activated by herpesviral thymidine kinase → inhibits viral DNA polymerase and terminates viral DNA chain; active vs HSV-1, HSV-2, and VZV; not active vs CMV (which lacks TK).

A broad-spectrum benzimidazole anthelmintic that binds helminth β-tubulin → inhibits microtubule polymerisation → impairs glucose uptake and worm metabolism; first-line for most intestinal roundworms; also active against tissue helminths (hydatid, neurocysticercosis) at higher doses; teratogenic — avoid in first trimester.

A class of CCNS anticancer drugs that form covalent DNA adducts (alkyl groups at N7 of guanine) → inter- and intra-strand crosslinks → DNA replication failure → apoptosis; examples: cyclophosphamide, cisplatin, melphalan.

A broad-spectrum polyene macrolide antifungal that binds ergosterol in fungal membranes, forming transmembrane pores causing ion leak and fungal cell death; the gold standard for severe fungal infections; dose-limited by nephrotoxicity (reduced by liposomal formulation).

A coordinated institutional programme to optimise antimicrobial use through formulary restriction, prospective audit-and-feedback, IV-to-oral switch, PK/PD-guided dosing, and education.

The WHO-recommended first-line treatment for uncomplicated P. falciparum malaria; combines an artemisinin derivative (artemether, artesunate, dihydroartemisinin) with a longer-acting partner drug; the artemisinin component acts rapidly via free-radical generation from endoperoxide bridge activation by haem iron.

Presence of bacteria in urine (≥10⁵ CFU/mL on clean-catch specimen) without symptoms of UTI; treatment is beneficial only in pregnancy and before urological procedures, not in other populations.

Area under the concentration-time curve divided by the MIC; key PK/PD index for concentration-dependent killers (aminoglycosides, fluoroquinolones) that predicts clinical and microbiological efficacy.

A class of antifungals that inhibit CYP51 (14α-demethylase), blocking the conversion of lanosterol to ergosterol; primarily fungistatic; includes triazoles (fluconazole, voriconazole, itraconazole, posaconazole) for systemic use and imidazoles for topical use.

Describes an antimicrobial that directly kills bacteria; preferred for infections where host immune clearance is unreliable (endocarditis, meningitis, immunocompromised patients).

Describes an antimicrobial that inhibits bacterial growth and replication without directly killing the organism; clearance depends on host immune function.

A diarylquinoline anti-TB drug that inhibits mycobacterial ATP synthase (F1Fo subunit); bactericidal; used in MDR-TB regimens; prolonged half-life (~5.5 months); QT prolongation risk.

The broadest-spectrum β-lactam class (imipenem, meropenem, ertapenem) with a modified ring structure that resists most β-lactamases; reserved as last-resort agents for ESBL and AmpC-producing organisms.

A combination of ceftazidime (anti-Pseudomonas cephalosporin) with avibactam (non-β-lactam β-lactamase inhibitor); active against KPC- and OXA-48-producing CRE; does not inhibit NDM metallo-β-lactamase.

Anticancer drugs active in any phase of the cell cycle, including G0 (quiescent cells); examples: alkylating agents (cyclophosphamide, cisplatin), anthracyclines (doxorubicin). Useful against tumours with large quiescent fractions.

Anticancer drugs that kill cells primarily during a specific phase of the cell cycle; examples: antimetabolites (S-phase), vinca alkaloids and taxanes (M-phase), bleomycin/etoposide (G2/M). Less effective against slow-growing tumours with large G0 fractions.

A riminophenazine anti-leprosy dye that binds mycobacterial DNA; bacteriostatic against M. leprae and has anti-inflammatory (anti-ENL) properties; causes orange-brown skin pigmentation (reversible) and GI adverse effects.

A last-resort polypeptide antibiotic that disrupts gram-negative bacterial outer membranes by displacing divalent cations from LPS; reserved for XDR gram-negative organisms; significant nephrotoxicity.

Diaminodiphenylsulfone — a bacteriostatic anti-leprosy agent that inhibits dihydropteroate synthase (folate synthesis); can cause haemolytic anaemia (severe in G6PD deficiency) and methaemoglobinaemia.

A cyclic lipopeptide antibiotic active only against gram-positive organisms via calcium-dependent membrane depolarisation; inactivated by pulmonary surfactant — not to be used for pneumonia; first-line for MRSA bacteraemia and VRE.

A metric of antibiotic consumption measured as the total number of days any patient received a specific antibiotic, per 1,000 patient-days; the standard measure used by stewardship programmes.

The practice of switching from broad-spectrum empiric antibiotic therapy to a narrower, targeted regimen once the causative pathogen and its susceptibilities are identified from culture results.

An EDTA analogue iron chelator that reduces intramyocardial free iron available for anthracycline-mediated free radical generation; cardioprotective agent used to prevent cumulative doxorubicin cardiomyopathy when approaching the cumulative dose threshold.

A microfilaricidal drug that enhances immune recognition and killing of filarial microfilariae; used for lymphatic filariasis treatment and mass drug administration; contraindicated in onchocerciasis (causes severe ocular Mazzotti reaction) and Loa loa co-infection (encephalopathy risk).

A class of HCV-specific drugs that target viral NS3/4A protease, NS5A, or NS5B polymerase; pan-genotypic combinations achieve >95% sustained virological response (cure) in 8–12 weeks of treatment with minimal adverse effects.

A second-generation INSTI with a high genetic barrier to resistance; preferred component of first-line ART globally and in India (TLD regimen); once-daily dosing; minimal CYP drug interactions; requires double-dosing (50mg BD) when co-administered with rifampicin.

Directly Observed Treatment Short-course — the WHO strategy for TB control in which every dose of anti-TB medication is swallowed in the presence of a trained observer; the cornerstone of the RNTCP in India.

A class of antifungals (caspofungin, micafungin, anidulafungin) that inhibit β-(1,3)-D-glucan synthase, disrupting fungal cell wall synthesis; fungicidal against Candida; inactive against Cryptococcus; IV administration; minimal drug interactions and toxicity.

A membrane-bound transporter in bacteria that actively exports antibiotic molecules out of the cell; upregulation confers multidrug resistance in organisms such as Pseudomonas aeruginosa.

The principal sterol in fungal cell membranes (analogous to cholesterol in human cells); its structural difference from cholesterol is the primary basis for selective toxicity of polyene and azole antifungals.

Extended-spectrum β-lactamase — an enzyme produced by certain gram-negative bacteria (E. coli, Klebsiella) that hydrolyses third-generation cephalosporins and penicillins; typically encoded on transferable plasmids.

A group of high-priority multidrug-resistant organisms responsible for the majority of hospital-acquired infections: Enterococcus faecium, Staphylococcus aureus (MRSA), Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.

An anti-TB bacteriostatic agent that inhibits arabinosyl transferase (embB), blocking arabinogalactan cell-wall synthesis; primary role is resistance prevention; causes dose-dependent optic neuritis (monitor visual acuity and colour vision monthly; stop immediately if visual changes occur).

The prescribing of antibiotics for the sex partner(s) of a patient diagnosed with an STD without individual clinical assessment of the partner; evidence-based for chlamydia and gonorrhoea prevention.

An antifungal prodrug converted by fungal cytosine deaminase to 5-fluorouracil (5-FU) → inhibits fungal RNA/DNA synthesis; used only in combination with amphotericin B for cryptococcal meningitis induction; rapid resistance emergence precludes monotherapy.

A synthetic antibacterial class that inhibits bacterial DNA gyrase and topoisomerase IV; bactericidal, concentration-dependent; examples: ciprofloxacin (gram-negative), levofloxacin (respiratory), moxifloxacin (anaerobic spectrum).

A urinary antiseptic that inhibits MurA (first step of peptidoglycan synthesis); active against most ESBL-producing E. coli; available as a 3g single oral dose for uncomplicated UTI; not absorbed systemically.

Transfer of genetic material between bacteria by means other than reproduction, including plasmids, transposons, and integrons; the primary mechanism by which resistance genes spread between species and genera.

A potentially fatal complication of Strongyloides stercoralis in immunocompromised hosts, in which the autoinfection cycle accelerates dramatically → massive larval burden → intestinal perforation → bacteraemia. Prevented and treated with ivermectin.

A dormant, non-replicating hepatic stage of Plasmodium vivax and P. ovale that persists in liver hepatocytes after the primary infection; can reactivate weeks to years later causing relapse; eliminated only by primaquine.

A selective BCR-ABL tyrosine kinase inhibitor; first targeted anticancer agent; transforms CML (chronic myeloid leukaemia) from a fatal disease to a manageable chronic condition; the IRIS trial demonstrated dramatic superiority to interferon-alpha; also active vs c-KIT (GIST) and PDGFR.

An antiretroviral class that inhibits the strand transfer step of HIV integrase, preventing integration of viral cDNA into the host chromosome; examples: dolutegravir (DTG), bictegravir, raltegravir; preferred first-line class due to high genetic barrier to resistance and tolerability.

An inflammatory syndrome occurring in HIV patients shortly after ART initiation, when the recovering immune system mounts exaggerated responses against pre-existing opportunistic infections (TB, cryptococcal, CMV); treated by continuing ART and adding corticosteroids for severe manifestations.

A prodrug anti-TB agent activated by mycobacterial KatG to inhibit InhA (enoyl-ACP reductase) → blocks mycolic acid synthesis; most potent early bactericidal ATT drug; can cause peripheral neuropathy (prevented by pyridoxine co-administration).

A macrocyclic lactone that activates invertebrate-specific glutamate-gated chloride channels → hyperpolarisation → flaccid paralysis; drug of choice for Strongyloides stercoralis (superior to albendazole); also used for filariasis MDA, scabies, and cutaneous larva migrans; avoid in pregnancy.

A systemic inflammatory reaction (fever, rigors, myalgia, hypotension) occurring within 2–8 hours of the first dose of penicillin for spirochaetal infections (syphilis, Lyme disease); caused by release of Treponema lipoproteins from killed organisms; not an allergy.

A reduced folate (5-formyl-THF) that bypasses dihydrofolate reductase (DHFR) inhibition; used in two distinct contexts: (1) rescue after high-dose methotrexate (protecting normal tissues); (2) modulation of 5-FU (stabilising the ternary TS-FdUMP-leucovorin inhibitory complex to enhance anti-tumour effect).

An oxazolidinone antibiotic that blocks 70S ribosomal initiation complex formation at the 50S subunit; bacteriostatic against Staphylococcus/Enterococcus; used for MRSA and VRE infections; 100% oral bioavailability; risk of myelosuppression and serotonin syndrome.

A lipid-encapsulated formulation of amphotericin B preferentially phagocytosed by macrophages in the reticuloendothelial system; first-line treatment for visceral leishmaniasis (kala-azar) in India; the liposomal delivery targets drug to macrophages where Leishmania resides, reducing systemic nephrotoxicity.

An anti-amoebic drug that acts within the intestinal lumen to kill E. histolytica cysts; examples include diloxanide furoate and paromomycin; not absorbed systemically; used after tissue amoebicide treatment to prevent relapse and transmission.

Multidrug-resistant tuberculosis — M. tuberculosis infection resistant to at least isoniazid AND rifampicin, the two most potent first-line ATT drugs; treated with WHO Group A drugs (bedaquiline, linezolid, levofloxacin/moxifloxacin).

A thiol-containing uroprotective agent that specifically reacts with acrolein (the urotoxic metabolite of cyclophosphamide/ifosfamide) in urine to form a non-toxic compound; prevents haemorrhagic cystitis without impairing antitumour efficacy.

An oral alkylphospholipid drug for visceral leishmaniasis that inhibits leishmanial phosphatidylcholine biosynthesis; the first oral anti-leishmanial agent; teratogenic — contraindicated in pregnancy, with mandatory contraception for 3 months post-treatment.

The lowest concentration of an antibiotic that prevents visible growth of a microorganism after overnight incubation; the reference point for PK/PD dosing indices.

Methicillin-resistant Staphylococcus aureus — carries the mecA gene encoding PBP2a, which has low β-lactam affinity, conferring resistance to all β-lactam antibiotics including carbapenems.

An invasive fungal infection caused by Mucorales (Mucor, Rhizopus, Lichtheimia); characterised by tissue infarction due to angioinvasion; associated with uncontrolled diabetes and corticosteroid use; treated with liposomal amphotericin B + urgent surgical debridement; intrinsically resistant to voriconazole.

The WHO-recommended combination treatment for leprosy using rifampicin, dapsone, and clofazimine (MB) or rifampicin and dapsone (PB); introduced in 1982 to prevent dapsone resistance and achieve rapid cure.

Leprosy with >5 skin lesions or smear-positive (BI ≥1+); reflects lower cell-mediated immunity (lepromatous end of spectrum); treated with 3-drug MDT for 12 months.

Infection of the central nervous system with larvae (cysticerci) of Taenia solium; the most common cause of acquired epilepsy in developing countries; treated with albendazole (or praziquantel) combined with corticosteroids and antiepileptic drugs — corticosteroid cover is mandatory to prevent inflammatory encephalopathy.

An anthelmintic that uncouples oxidative phosphorylation in tapeworm mitochondria; used for intestinal taeniasis (T. saginata, T. solium); very poorly absorbed — cannot reach brain cysts (not for neurocysticercosis).

A urinary antiseptic concentrated in renal tubular secretion; active against common uropathogens; restricted to lower (uncomplicated) UTI — inadequate tissue levels make it ineffective for pyelonephritis; contraindicated in eGFR <30 mL/min.

An antiretroviral drug class that mimics natural nucleosides; phosphorylated intracellularly → competitive inhibitor of viral RT AND obligate DNA chain terminator (lacks 3'-OH group); backbone of all modern ART regimens (examples: tenofovir, lamivudine).

An oral influenza neuraminidase inhibitor that prevents newly assembled influenza virions from detaching from infected cells; active vs influenza A and B; must be started within 48 hours of symptom onset for maximum clinical benefit.

Leprosy with 1–5 skin lesions and/or smear-negative; reflects higher cell-mediated immunity (tuberculoid end of spectrum); treated with 2-drug MDT for 6 months.

A bacterial enzyme (transpeptidase) responsible for cross-linking the peptidoglycan cell wall; the target for β-lactam antibiotics. Resistance via acquisition of PBP2a (low β-lactam affinity) accounts for MRSA resistance to all β-lactams.

A mutant lysosomal transporter in P. falciparum that pumps chloroquine out of the parasite's digestive vacuole, preventing accumulation to levels that inhibit haem polymerisation; the primary mechanism of chloroquine resistance in P. falciparum.

Persistent suppression of bacterial growth after antibiotic concentrations fall below the MIC; most pronounced with aminoglycosides and fluoroquinolones, justifying once-daily dosing.

A broad-spectrum anthelmintic that increases Ca²⁺ permeability of schistosome and tapeworm tegument → spastic paralysis → tegument disruption → immune-mediated death; drug of choice for schistosomiasis, taeniasis, and neurocysticercosis (with corticosteroids); NOT effective vs Fasciola hepatica.

Bacterial infection of the kidney parenchyma, characterised by fever, flank pain, and costovertebral angle tenderness; requires tissue-penetrating antibiotics (fluoroquinolone or beta-lactam) and urine culture.

A depolarising neuromuscular blocking anthelmintic that acts as a cholinomimetic at helminth nicotinic acetylcholine receptors → sustained depolarisation → spastic paralysis → worm expulsion; covers Ascaris, hookworm, Enterobius; safe in pregnancy; NOT effective vs Trichuris.

A prodrug active only in acidic microenvironments (caseous lesions, macrophage phagolysosomes); converted to pyrazinoic acid by mycobacterial pyrazinamidase; used only in the 2-month intensive phase; key drug that shortened TB treatment from 12 to 6 months.

Elimination of both blood-stage parasites (by a schizonticide) AND liver-stage hypnozoites (by primaquine) in P. vivax or P. ovale malaria; required to prevent relapse.

A recombinant urate oxidase that converts uric acid to allantoin (more soluble); used for treatment of established tumour lysis syndrome and high-risk prophylaxis; contraindicated in G6PD deficiency (generates H₂O₂ → oxidative haemolysis).

A non-allergic infusion reaction to vancomycin caused by direct mast-cell histamine release; characterised by flushing and erythema of the face, neck, and upper body; prevented by slowing the infusion rate to ≥60 min.

An RNA-dependent DNA polymerase encoded by HIV and other retroviruses; converts viral genomic RNA into double-stranded DNA; absent in normal human cells; the target of NRTIs and NNRTIs.

An ansamycin antibiotic that inhibits mycobacterial RNA polymerase beta subunit; the most important sterilising agent in ATT; causes orange discolouration of secretions (harmless); potent CYP450 inducer causing multiple drug interactions.

A single-dose anti-leprosy regimen of Rifampicin + Ofloxacin + Minocycline; used for single-lesion paucibacillary leprosy; provides comparable cure rates to 6-month PB MDT in this specific subgroup.

The ability of an antimicrobial agent to harm the pathogen at doses that do not significantly harm the host, exploiting structural or metabolic differences between pathogen and host cells.

A pharmacogenomic phenotype (NAT2 gene polymorphism) characterised by slower hepatic N-acetylation of isoniazid; results in higher plasma INH levels and increased risk of peripheral neuropathy; approximately 50% of the Indian population are slow acetylators.

Treatment of an infection based on clinical syndrome and likely pathogen(s) without waiting for microbiological confirmation; standard approach for STDs when laboratory testing is unavailable or delayed.

Time above MIC — the fraction of the dosing interval during which free drug concentration exceeds the MIC; the key pharmacodynamic parameter for β-lactam dosing (target: ≥40–50% of interval).

An allylamine antifungal that inhibits squalene epoxidase, blocking ergosterol synthesis and causing toxic squalene accumulation; fungicidal against dermatophytes; first-line oral treatment for onychomycosis; hepatotoxic (monitor LFTs).

A glutamic acid derivative with potent anti-inflammatory (TNF-α inhibition) and immunomodulatory properties; first-line for severe ENL in male and post-menopausal female patients; absolutely contraindicated in fertile women due to teratogenicity (phocomelia).

An anti-amoebic drug that kills invasive E. histolytica trophozoites in the colonic wall, liver, and other tissues; metronidazole and tinidazole are the primary tissue amoebicides.

A Type IV (T-cell mediated) immunological reaction in borderline leprosy, characterised by inflammation of pre-existing skin lesions and acute peripheral neuropathy; treated with prednisolone; MDT must be continued.

Erythema nodosum leprosum — a Type III (immune complex) reaction in LL/BL leprosy, characterised by crops of new tender erythematous nodules plus systemic features (fever, iritis, orchitis); treated with thalidomide (males/non-fertile females) or clofazimine; MDT must be continued.

The evidence-based principle that an HIV-positive person with a virologically suppressed (undetectable) viral load on ART cannot sexually transmit HIV; established by the PARTNER and Opposites Attract studies; central to HIV de-stigmatisation and prevention.

Acute cystitis in a non-pregnant, non-catheterised, otherwise healthy adult woman with no structural urinary abnormality; the most common bacterial infection requiring antibiotics in outpatient practice.

A vinca alkaloid that inhibits tubulin polymerisation → prevents mitotic spindle formation → M-phase arrest; unique among cytotoxic drugs in causing minimal myelosuppression (enabling inclusion in intensive combinations); dose-limited by peripheral neuropathy and autonomic neuropathy (constipation, paralytic ileus).

An extended-spectrum triazole antifungal that is first-line for invasive aspergillosis; also active against Candida krusei and C. glabrata; metabolised by CYP2C19 (genetic polymorphism requires TDM); unique adverse effect: visual disturbances (photopsia).

Obligate intracellular endosymbiotic bacteria found within filarial worm tissues; essential for worm fertility and survival; depletion by doxycycline (4–6 weeks) causes adult filarial worm sterilisation and eventual death (macrofilaricidal effect).