PH9.1-7 | Miscellaneous Therapeutics — Glossary

A low-resource bedside test for venom-induced consumption coagulopathy in snake bite; fresh blood placed in a clean glass tube fails to clot within 20 minutes if VICC is present.

Systemic (oral/IV) carbonic anhydrase inhibitor; used for acute angle-closure glaucoma and when topical therapy is insufficient; ADR: hyperchloraemic metabolic acidosis, renal calculi, paraesthesia, sulfonamide cross-reaction.

A vaccine component that enhances immunogenicity by activating innate immune pattern recognition receptors, providing a 'danger signal'; examples include aluminium salts (alum) and AS04 (alum + MPL).

The irreversible modification of the organophosphate-AChE complex that renders acetylcholinesterase permanently inactive; occurs at variable times (hours to days) depending on the specific organophosphate.

The irreversible covalent modification of the organophosphate-AChE complex that makes the bond permanent; beyond this point pralidoxime is ineffective. (Also relevant in PH9.2; heavy metal 'aging' analogies apply to fixed metal-enzyme complexes.)

Recombinant IL-2 (interleukin-2) that activates T-cells and NK cells; approved for metastatic renal cell carcinoma and melanoma but causes severe capillary leak syndrome.

Intravitreal injections of anti-vascular endothelial growth factor agents (ranibizumab, bevacizumab, aflibercept) that block pathological neovascularisation in wet age-related macular degeneration and diabetic macular oedema.

A chemical agent safe for application to living tissue (skin, wounds, mucous membranes) that reduces the microbial burden to prevent infection.

Polyvalent anti-snake venom containing antibodies against the Big Four Indian snake venoms; given IV in cases of proven envenomation (positive 20WBCT for haemotoxic or neurological signs for neurotoxic).

A clear fluid produced by the ciliary body that fills the anterior and posterior chambers of the eye; its production-drainage balance determines intraocular pressure.

A purine antimetabolite prodrug metabolised to 6-mercaptopurine; inhibits lymphocyte DNA synthesis via 6-TGN incorporation and purine depletion.

The appearance of blue-staining granules (residual ribosomal RNA aggregates) in red blood cells on Giemsa staining; pathognomonic of lead poisoning among other causes; results from lead inhibiting ribonuclease and pyrimidine 5'-nucleotidase.

Live attenuated Mycobacterium bovis instilled into the bladder to activate local macrophage and T-cell anti-tumour immunity; the most effective intravesical therapy for non-muscle-invasive bladder cancer.

An oxidising agent that releases reactive oxygen radicals, killing Propionibacterium acnes; also keratolytic and anti-comedogenic; does not promote antibiotic resistance — should be combined with topical antibiotics.

A cardioselective (β1-selective) beta-blocker eye drop; less IOP-reducing potency than timolol but significantly reduced risk of bronchospasm; appropriate for patients with mild asthma who require beta-blocker therapy for glaucoma.

A selective alpha-2 adrenergic agonist that reduces aqueous production and increases uveoscleral outflow; absolutely contraindicated in infants <2 years (CNS depression via immature BBB).

A class of immunosuppressants (cyclosporine, tacrolimus) that inhibit the phosphatase calcineurin, preventing NFAT-driven IL-2 transcription and T-cell activation.

A synthetic vitamin D3 analogue that binds the vitamin D receptor (VDR) in keratinocytes, inhibiting cell cycle progression and normalising differentiation in psoriasis; does not cause skin atrophy.

A life-threatening adverse effect of high-dose aldesleukin characterised by hypotension, pulmonary oedema, and oliguria due to vascular hyperpermeability.

A molecule with two or more electron-donating groups that coordinates with a metal ion to form a stable ring complex (chelate), increasing metal excretion in urine or bile.

A biguanide antiseptic with broad-spectrum bactericidal activity and residual (substantive) skin-binding property; used for surgical hand prep, preoperative skin antisepsis, wound care, and oral rinse.

The unbroken temperature-controlled supply chain from vaccine manufacturer to patient that preserves vaccine potency; most vaccines require +2°C to +8°C.

A vaccine in which a polysaccharide antigen is covalently linked to a carrier protein, converting a T-independent antigen to a T-dependent one and enabling immunological memory in infants under 2 years.

Oral thiol chelator used for Wilson's disease (copper), lead, and mercury; significant ADR profile including aplastic anaemia, immune complex nephropathy, and myasthenia gravis-like syndrome; requires lifelong use in Wilson's disease.

A hydroxamate chelator highly selective for iron (and aluminium); forms ferrioxamine complex (excreted as 'vin rosé' urine); the specific antidote for acute iron poisoning; not effective for lead or mercury.

British Anti-Lewisite — a dithiol chelating agent given IM for arsenic, mercury, lead, and gold poisoning; absolutely contraindicated in iron and cadmium poisoning (toxic complexes).

A chemical agent applied to inanimate surfaces or instruments that reduces the microbial burden; many are too toxic for tissue use at effective concentrations.

Oral dithiol chelating agent (dimercaptosuccinic acid) used for lead, mercury, and arsenic poisoning; preferred over BAL for paediatric lead (oral, less toxic, outpatient-suitable).

Topical carbonic anhydrase inhibitors that reduce aqueous humour production; local ADR: stinging on instillation (dorzolamide), metallic taste.

Recombinant human G-CSF (granulocyte colony-stimulating factor) that stimulates neutrophil production from bone marrow precursors; used to treat or prevent febrile neutropenia.

A competitive GABA-A benzodiazepine receptor antagonist used to reverse benzodiazepine-induced sedation; contraindicated with TCA co-ingestion (seizure risk) and in benzodiazepine-dependent patients.

A 2% alkaline aldehyde solution (e.g. Cidex) used as a high-level disinfectant/chemical sterilant for heat-sensitive endoscopes and instruments; tissue toxic — never used as an antiseptic.

The proportion of a population that must be immune to an infection to prevent sustained transmission chains and thus protect unvaccinated individuals; determined by the pathogen's R₀.

Elimination of all microorganisms except high-burden bacterial spores; required for semi-critical items (endoscopes, laryngoscopes); achieved with glutaraldehyde 2% for 20–30 minutes.

Inosine monophosphate dehydrogenase — the rate-limiting enzyme in de novo purine synthesis, selectively expressed in activated lymphocytes and targeted by mycophenolate.

A vaccine containing pathogens killed by heat or chemical treatment; cannot cause disease and is safe in immunocompromised patients, but requires multiple doses and boosters.

The fluid pressure within the eye, normally 10–21 mmHg; chronically elevated IOP is the primary risk factor for glaucomatous optic nerve damage.

A complex of iodine with a carrier molecule (e.g. polyvinylpyrrolidone in povidone-iodine/Betadine) that provides sustained slow release of free iodine; better tolerated and longer-acting than elemental iodine.

13-cis-retinoic acid — oral retinoid for severe nodular acne; reduces sebum production by ~90%, normalises follicular keratinisation; Pregnancy Category X (teratogenic at any dose); requires pregnancy prevention programme.

Small molecule drugs (tofacitinib, baricitinib) that block Janus kinase enzymes used by cytokine receptors for intracellular signalling, reducing inflammatory cytokine effects.

A golden-brown ring of copper deposits in Descemet's membrane at the periphery of the cornea, visible on slit-lamp examination; pathognomonic of Wilson's disease when present with neurological features.

A vaccine containing a viable but weakened pathogen that replicates in the host and produces strong, long-lasting immunity; absolutely contraindicated in immunocompromised patients.

An antifolate DMARD used for moderate-severe psoriasis at 7.5–25 mg ONCE WEEKLY (not daily); inhibits DHFR in rapidly proliferating T-cells and keratinocytes; requires folic acid supplementation and monthly monitoring of FBC, LFTs, and creatinine.

A neurological syndrome caused by methylmercury poisoning from contaminated fish; characterised by cerebellar ataxia, sensory neuropathy, constricted visual fields, and deafness; originally described in Minamata Bay, Japan (1950s).

Mammalian target of rapamycin — a kinase that drives T-cell cycle progression downstream of the IL-2 receptor; inhibited by sirolimus and everolimus.

A prodrug of mycophenolic acid that selectively inhibits IMPDH, blocking de novo purine synthesis specifically in lymphocytes.

The antidote for paracetamol poisoning; a glutathione precursor/substitute that replenishes GSH stores and directly neutralises NAPQI; most effective within 8–10 hours of ingestion.

A competitive opioid receptor antagonist (highest affinity for μ-receptors) that rapidly reverses opioid-induced respiratory depression; half-life ~60–90 min, requiring repeat dosing.

N-acetyl-p-benzoquinone imine — the reactive hepatotoxic metabolite of paracetamol produced by CYP2E1; normally detoxified by glutathione, but accumulates in overdose causing centrilobular hepatic necrosis.

The anatomical drainage pathway for eye drops: excess fluid drains from the conjunctival sac through the lacrimal canaliculi, nasolacrimal duct, and nasal cavity, where the highly vascular nasal mucosa absorbs drug directly into the systemic circulation, bypassing hepatic first-pass metabolism.

Nuclear Factor of Activated T-cells — a transcription factor that drives IL-2 gene expression after calcineurin-mediated dephosphorylation; the molecular target of calcineurin inhibitors.

New-onset diabetes mellitus after transplantation — a major metabolic complication of tacrolimus more so than cyclosporine, caused by beta-cell toxicity and insulin resistance.

Infection by organisms that do not normally cause disease in immunocompetent individuals but become dangerous under immunosuppression (e.g. PCP, CMV, invasive fungal infections).

A synthetic pyrethroid insecticide that prolongs voltage-gated sodium channel opening in arthropod neurons, causing paralysis; first-line for scabies (5%) and head lice (1%).

An inorganic sunscreen agent (zinc oxide, titanium dioxide) that reflects and scatters UV radiation; photostable, non-comedogenic, and suitable for sensitive skin, infants, and acne-prone skin.

A direct muscarinic agonist that contracts the ciliary muscle and iris sphincter, opening the trabecular meshwork; used in acute angle-closure and narrow-angle glaucoma; ADR: spasm of accommodation (induced myopia).

An acetylcholinesterase reactivator that cleaves the organophosphate-AChE bond and restores enzyme activity; must be given BEFORE irreversible 'aging' of the OP-AChE complex.

An α-1 adrenergic receptor blocker used specifically for Indian red scorpion (Mesobuthus tamulus) sting, which causes massive catecholamine release and autonomic storm with hypertension and pulmonary oedema.

The immune response to first antigen encounter — characterised by a latency of 1–2 weeks, low-titre IgM followed by IgG, and establishment of memory cells.

A class of anti-glaucoma drugs (latanoprost, bimatoprost, travoprost) that increases uveoscleral (unconventional) aqueous outflow; the most potent single-agent IOP-reducing drugs; once-daily evening dosing; local ADR: iris pigmentation, eyelash hypertrichosis.

A technique where the patient presses a finger over the nasolacrimal punctum (inner corner of the eye) for 2–3 minutes after instilling eye drops, reducing systemic absorption by ~40–50% by blocking nasolacrimal drainage.

Cationic detergent antiseptic/disinfectant (e.g. benzalkonium chloride) that disrupts microbial cell membranes; provides low-level disinfection; inactivated by soap, organic matter, and Pseudomonas aeruginosa.

A class of vitamin A derivatives (natural and synthetic) that bind nuclear retinoic acid receptors (RARs) to regulate gene expression; used topically (tretinoin, adapalene) for acne and systemically (isotretinoin) for severe acne, and (acitretin) for psoriasis.

The rapid (2–3 days), high-magnitude, predominantly IgG response on re-exposure to a previously encountered antigen; the basis for booster vaccine doses.

A framework for selecting the required level of decontamination based on the item's intended use: Critical (sterile tissue) → sterilise; Semi-critical (mucous membrane) → high-level disinfect; Non-critical (intact skin) → low-level disinfect.

A measure of how much UVB radiation is required to produce sunburn with a sunscreen compared to without; SPF does not measure UVA protection — 'broad spectrum' labelling is required for UVA cover.

The complete elimination of all microbial life including bacterial endospores; required for critical items that enter sterile body tissues.

The property of chlorhexidine to bind to keratin in skin and remain active for hours after application, providing prolonged residual antimicrobial protection.

A vaccine containing only purified antigenic components (proteins or polysaccharides) from the pathogen; highly safe; requires adjuvants and booster doses for adequate immunogenicity.

The phenomenon of reduced response to topical corticosteroids after prolonged continuous use, necessitating rotation or drug holidays; a key limitation of topical steroid use in psoriasis.

A non-selective beta-blocker (β1 and β2) used as an eye drop to reduce aqueous humour production; absorbed systemically via the nasolacrimal duct; contraindicated in asthma and COPD.

A characteristic syndrome of signs and symptoms produced by a specific class of toxins, enabling empirical antidote selection before laboratory confirmation.

A vaccine made from bacterial exotoxins that have been chemically inactivated to abolish toxicity while retaining immunogenicity; the immune response targets the toxin (e.g. tetanus, diphtheria).

A heat-sensitive label on the vaccine vial that changes colour irreversibly when the vial has been exposed to excessive heat, indicating potential loss of vaccine potency.

Venom-induced consumption coagulopathy — caused by haemotoxic snake venoms (Russell's viper, saw-scaled viper); characterised by activation and exhaustion of coagulation factors and fibrinogen, leading to systemic bleeding.

Orange-pink colouration of urine during deferoxamine therapy in iron poisoning, caused by the ferrioxamine complex (iron-deferoxamine chelate) being excreted in urine; confirms that iron chelation is occurring.

Vaccine-induced immune thrombocytopenia and thrombosis — a rare but serious adverse event after adenoviral vector COVID-19 vaccines, caused by anti-PF4 antibodies; presents with thrombosis and thrombocytopenia.