Pharmacotherapeutics: infectious diseases, oncology and endocrine disorders

In short

Pharmacotherapeutics is the applied science of choosing, dosing, monitoring and stopping drug therapy for a specific patient and disease, using pathophysiology, pharmacokinetics, evidence and guidelines together. Infectious diseases, cancer and endocrine disorders are the three areas where a clinical pharmacist's input changes outcomes most — antimicrobial stewardship, chemotherapy dose verification and insulin titration are everyday hospital tasks. In India the practice follows NTEP (TB), NACO (HIV), NVBDCP (malaria), ICMR treatment guidelines, NCG (National Cancer Grid) protocols and RSSDI/ADA diabetes standards, inside the legal frame of the Drugs and Cosmetics Act, 1940 with Schedule H/H1/X and the Pharmacy Practice Regulations, 2015. These topics carry heavy marks in Pharm.D Pharmacotherapeutics papers and in GPAT/NIPER-type exams, and dominate interviews for clinical pharmacist, medical information, pharmacovigilance and medical-writing roles.

Explained

Framework common to all three areas

• Therapeutic plan: indication → goal (cure, control, palliation) → drug choice → dose/route/frequency/duration → monitoring parameters (efficacy + toxicity) → endpoint or de-escalation.
• Evidence hierarchy: meta-analysis/RCT > cohort > case-control > case series > expert opinion; Indian guidelines adapt global evidence to local resistance, cost and availability.
• Pharmacokinetic individualisation: adjust for renal function (Cockcroft-Gault/CKD-EPI), hepatic impairment (Child-Pugh), weight, age, pregnancy and drug interactions.
• Therapeutic drug monitoring (TDM) drugs in these areas: vancomycin, aminoglycosides, methotrexate, busulfan; peak/trough timing decides interpretation.
• Legal/practice frame: antimicrobials and anticancer drugs are Schedule H/H1 (H1 needs a separate register kept 3 years); narcotic analgesics in oncology fall under the NDPS Act, 1985 with Recognised Medical Institution rules easing morphine access; adverse events are reported to PvPI (IPC, Ghaziabad) on the suspected-ADR form.

Infectious diseases

• Empirical vs definitive therapy: empirical = broad cover chosen from likely organism, site and local sensitivity pattern, started immediately; definitive = narrowed after culture and sensitivity. De-escalate at 48-72 h.
• Antimicrobial classification by mechanism: cell-wall synthesis (β-lactams, vancomycin, daptomycin acts on membrane), protein synthesis (aminoglycosides, macrolides, tetracyclines, linezolid, clindamycin), nucleic acid (fluoroquinolones — DNA gyrase/topoisomerase IV; rifampicin — RNA polymerase), folate pathway (sulfamethoxazole-trimethoprim), membrane (polymyxins).
• Bactericidal vs bacteriostatic; PK/PD targets: time-dependent killing (β-lactams → maximise T>MIC, hence extended infusion), concentration-dependent (aminoglycosides, fluoroquinolones → Cmax/MIC, AUC/MIC), vancomycin AUC₂₄/MIC target ~400-600.
• Resistance mechanisms: enzymatic destruction (β-lactamases, ESBL, AmpC, carbapenemases NDM-1/OXA-48 — NDM first described from India), altered target (MRSA mecA/PBP2a, altered DNA gyrase), reduced uptake/porin loss, efflux pumps, biofilm. Drivers: over-the-counter sale, incomplete courses, agricultural use.
• Antimicrobial stewardship (AMS): ICMR/NCDC National Action Plan on AMR; hospital antibiotic policy, formulary restriction, pre-authorisation of reserve drugs, prospective audit and feedback, IV-to-oral switch, duration limits, surgical prophylaxis within 60 min of incision and usually stopped within 24 h. WHO AWaRe classification — Access, Watch, Reserve — guides selection.
• Common syndromes (typical Indian practice): community-acquired pneumonia — amoxicillin or amoxicillin-clavulanate ± macrolide, respiratory fluoroquinolone avoided where TB is possible (it masks TB and breeds fluoroquinolone-resistant TB); uncomplicated UTI — nitrofurantoin or fosfomycin; enteric fever — ceftriaxone or azithromycin (fluoroquinolone resistance is now high); cellulitis — cloxacillin/cefazolin, add cover for MRSA if risk; hospital-acquired/VAP — antipseudomonal β-lactam per local policy; febrile neutropenia — piperacillin-tazobactam or cefepime/carbapenem within 1 h.
• Sepsis: blood cultures then antibiotics within 1 h, 30 mL/kg crystalloid for hypoperfusion, vasopressor (noradrenaline first line) to MAP ≥65 mmHg, lactate clearance as a marker, source control.
• Tuberculosis (NTEP): intensive phase 2 months HRZE then continuation 4 months HRE (daily fixed-dose combinations, weight-band boxes); extend in CNS/bone TB (up to 9-12 months) with corticosteroids in TB meningitis/pericarditis. Pyridoxine with isoniazid prevents peripheral neuropathy. Drug-resistant TB uses all-oral regimens built on bedaquiline, linezolid, levofloxacin/moxifloxacin, clofazimine, cycloserine; the shorter BPaLM regimen (bedaquiline, pretomanid, linezolid, moxifloxacin) is being rolled out — composition and duration are updated periodically, so check the current NTEP guideline. Key toxicities: hepatotoxicity (H, R, Z), optic neuritis (ethambutol), hyperuricaemia (Z), QT prolongation (bedaquiline, moxifloxacin), linezolid myelosuppression/neuropathy. Rifampicin induces CYP3A4 — fails oral contraceptives, lowers many antiretrovirals.
• HIV (NACO): ART for all, regardless of CD4. First line commonly tenofovir + lamivudine + dolutegravir (TLD); NACO's national ART rollout is free. Monitor viral load, renal function (tenofovir), weight gain (dolutegravir). Cotrimoxazole prophylaxis and TB preventive therapy where indicated. Adherence >95% needed to prevent resistance.
• Malaria (NVBDCP): *P. falciparum* — artemisinin-based combination therapy (ACT: artesunate-sulfadoxine-pyrimethamine in most of India, artemether-lumefantrine in the North-East) plus single-dose primaquine as gametocytocide; *P. vivax* — chloroquine 3 days plus primaquine 14 days for radical cure, after screening for G6PD deficiency. Severe malaria — IV artesunate, then full oral ACT.
• Other common Indian infections: dengue (supportive, fluids, no NSAIDs/aspirin), leptospirosis (doxycycline/penicillin), scrub typhus (doxycycline/azithromycin), rabies prophylaxis (wound washing, cell-culture vaccine ± rabies immunoglobulin), tetanus, COVID-19 (supportive; steroids only in hypoxia).
• Antifungals/antivirals: fluconazole (candidiasis), amphotericin B — conventional vs liposomal (nephrotoxicity, infusion reactions, K⁺/Mg²⁺ loss), voriconazole (TDM, visual disturbance), echinocandins; oseltamivir for influenza; acyclovir for herpes/varicella.
• Vaccines and immunisation: Universal Immunisation Programme schedule — BCG, OPV, hepatitis B at birth; pentavalent and rotavirus at 6/10/14 weeks, IPV and PCV at 6 and 14 weeks (PCV booster at 9 months); measles-rubella at 9-12 months and 16-24 months.

Oncology

• Principles: cancer cells grow by Gompertzian kinetics; cell-cycle-specific drugs (antimetabolites, taxanes, vinca alkaloids) need prolonged exposure, cell-cycle-non-specific drugs (alkylators, anthracyclines) kill log-linearly with dose. Combination chemotherapy uses drugs with different mechanisms and non-overlapping toxicities at full dose to delay resistance.
• Treatment intents: neoadjuvant (shrink before surgery), adjuvant (eradicate micrometastases), curative/definitive, palliative; concurrent chemoradiation (e.g. cisplatin in head-and-neck and cervical cancer, a large Indian disease burden).
• Drug classes: alkylating agents (cyclophosphamide, ifosfamide, cisplatin/carboplatin as platinum analogues), antimetabolites (methotrexate, 5-FU, capecitabine, cytarabine, gemcitabine), antitumour antibiotics (doxorubicin, bleomycin), mitotic inhibitors (vincristine, paclitaxel, docetaxel), topoisomerase inhibitors (etoposide, irinotecan), hormonal agents (tamoxifen, aromatase inhibitors, bicalutamide, GnRH analogues), targeted small molecules (imatinib, erlotinib, trastuzumab-era HER2 drugs), monoclonal antibodies (rituximab, trastuzumab, bevacizumab), immune checkpoint inhibitors (nivolumab, pembrolizumab) and CAR-T (now available in India).
• Dosing: by body surface area (mg/m²); carboplatin by Calvert formula (AUC-based); fixed dosing for many biologicals; cap BSA at 2.0 m² per institutional policy; dose-band rounding reduces error.
• Key toxicities and their prevention: myelosuppression (nadir day 7-14; G-CSF support), nausea/vomiting (classify regimen emetogenicity → 5-HT₃ antagonist + dexamethasone + NK1 antagonist ± olanzapine for high-risk), mucositis, alopecia, cisplatin nephrotoxicity/ototoxicity (hydration + Mg/K supplementation, avoid other nephrotoxins), doxorubicin cardiotoxicity (cumulative dose limit ~450-550 mg/m², monitor LVEF, dexrazoxane), cyclophosphamide/ifosfamide haemorrhagic cystitis (hydration + mesna), vincristine neuropathy and fatal if given intrathecally (label "for intravenous use only"), bleomycin pulmonary fibrosis, methotrexate mucositis/nephrotoxicity (leucovorin rescue, urine alkalinisation), 5-FU cardiotoxicity/diarrhoea (DPD deficiency), capecitabine hand-foot syndrome, irinotecan cholinergic diarrhoea (atropine) then late diarrhoea (loperamide), immune-related adverse events (thyroiditis, colitis, pneumonitis — treated with steroids).
• Oncological emergencies: febrile neutropenia (ANC <500/mm³ with fever ≥38.3 °C — antibiotics within 1 h), tumour lysis syndrome (hyperkalaemia, hyperphosphataemia, hyperuricaemia, hypocalcaemia — hydration, allopurinol or rasburicase), superior vena cava obstruction, spinal cord compression, hypercalcaemia of malignancy (saline + zoledronic acid), extravasation of vesicants (stop, aspirate, antidote — dimethyl sulfoxide for anthracyclines, hyaluronidase for vinca).
• Supportive care and the pharmacist's role: verification of protocol, cycle number, dose, cumulative anthracycline dose, pre-medication, renal/hepatic dose modification, drug-drug interactions, antiemetic and pain ladder (WHO ladder; morphine under NDPS/RMI rules), handling cytotoxics in a Class II biological safety cabinet with PPE, spill kit and cytotoxic waste in the Bio-Medical Waste Management Rules, 2016 (as amended) yellow category.
• Access and policy in India: NCG uniform protocols, Ayushman Bharat PM-JAY packages, Jan Aushadhi and AMRIT pharmacies, NPPA price ceilings on many anticancer drugs, Section 84 compulsory-licence provisions of the Patents Act, 1970 (used for sorafenib in 2012; Section 92 covers government-notified emergencies).

Endocrine disorders

• Diabetes mellitus — diagnosis: FPG ≥126 mg/dL, 2-h OGTT ≥200 mg/dL, HbA1c ≥6.5%, or random ≥200 mg/dL with symptoms; prediabetes FPG 100-125, HbA1c 5.7-6.4%. India's "thin-fat" phenotype means BMI cut-offs are lower (overweight ≥23, obese ≥25 kg/m²) and abdominal obesity (waist ≥90 cm men, ≥80 cm women) matters more.
• Targets (individualise): HbA1c generally <7%, fasting 80-130 mg/dL, post-prandial <180 mg/dL; relax to 7.5-8% in elderly, frail, long diabetes duration or hypoglycaemia-prone patients.
• Type 2 drug classes: metformin (first line; biguanide, reduces hepatic gluconeogenesis; GI upset, B12 deficiency, withhold if eGFR <30), sulfonylureas (glimepiride — hypoglycaemia, weight gain), DPP-4 inhibitors (sitagliptin, teneligliptin — weight neutral), SGLT2 inhibitors (dapagliflozin, empagliflozin — cardiorenal benefit, genital mycotic infection, euglycaemic ketoacidosis), GLP-1 receptor agonists (liraglutide, semaglutide, dulaglutide — weight loss, nausea), pioglitazone (oedema, fracture, heart failure), acarbose (post-prandial, flatulence), insulin when HbA1c very high or catabolic.
• Comorbidity-driven choice: ASCVD/heart failure/CKD → SGLT2 inhibitor or GLP-1 RA regardless of HbA1c; obesity → GLP-1 RA; cost constraint → metformin + sulfonylurea (still the commonest Indian combination).
• Insulin: rapid-acting (lispro, aspart, glulisine — onset 10-15 min), regular (30 min, give 30 min before meals), NPH intermediate, long-acting analogues (glargine, detemir, degludec), premixed 30/70. Regimens: basal only, basal-bolus, premix twice daily. Typical start 0.1-0.2 U/kg/day basal, titrate by fasting glucose; total daily dose in type 1 roughly 0.5-1.0 U/kg/day split ~50% basal/50% bolus. Rotate injection sites to prevent lipohypertrophy; cold chain 2-8 °C, in-use pen at room temperature ~28 days.
• Hypoglycaemia: <70 mg/dL — "rule of 15": 15 g fast carbohydrate, recheck in 15 min; unconscious — IV 25% dextrose or glucagon. Beta-blockers mask warning symptoms.
• Acute complications: DKA (glucose >250, pH <7.3, HCO₃ <15-18, ketones positive) — IV normal saline, insulin infusion 0.1 U/kg/h, potassium replacement once K⁺ <5.2 with urine output, dextrose added when glucose <200-250, treat the precipitant (infection commonest in India), watch cerebral oedema in children. HHS — higher glucose (>600), osmolality >320 mOsm/kg, minimal ketosis, greater fluid deficit.
• Chronic complications and care bundle: retinopathy (annual fundus), nephropathy (annual urine albumin-creatinine ratio; ACE inhibitor/ARB), neuropathy (foot care, pregabalin/duloxetine/amitriptyline for painful neuropathy), ASCVD (statin, BP <130/80), vaccination, smoking cessation. Diabetes and TB often coexist in India — bidirectional NTEP screening.
• Thyroid: hypothyroidism — levothyroxine ~1.6 µg/kg/day, empty stomach 30-60 min before breakfast, no calcium/iron/antacid within 4 h, recheck TSH after 6-8 weeks; start 12.5-25 µg in elderly/ischaemic heart disease; pregnancy needs a ~30-50% dose rise and trimester-specific TSH targets. Hyperthyroidism — carbimazole/methimazole or propylthiouracil (preferred in first trimester; hepatotoxic), β-blocker for symptoms, radioiodine or surgery; watch agranulocytosis (sore throat, fever → stop and check counts). Thyroid storm — PTU + iodine (given ≥1 h after thionamide) + β-blocker + steroid. India's iodised-salt programme (NIDDCP) addresses iodine-deficiency goitre.
• Adrenal and corticosteroids: relative potency — hydrocortisone 1, prednisolone 4, methylprednisolone 5, dexamethasone ~25-30, with mineralocorticoid activity falling across the series. Addison's disease — hydrocortisone + fludrocortisone, double the dose during illness ("sick-day rules"), parenteral in crisis with saline. Cushing's syndrome is most often iatrogenic; taper steroids after >2-3 weeks of use to avoid adrenal insufficiency. Steroid adverse effects: hyperglycaemia, osteoporosis, infection, peptic ulcer, myopathy, growth retardation, psychosis.
• Other endocrine topics examined: PCOS (lifestyle, metformin, combined oral contraceptive, letrozole for ovulation), osteoporosis (calcium 1,000-1,200 mg + vitamin D, bisphosphonates taken fasting upright with water, denosumab, teriparatide; T-score ≤ −2.5), obesity pharmacotherapy (orlistat, GLP-1 RA), hyperprolactinaemia (cabergoline), acromegaly (octreotide), diabetes insipidus (desmopressin) and SIADH (fluid restriction, tolvaptan).

Key points

• Empirical therapy - immediate broad-spectrum cover based on site, likely organism and local sensitivity, narrowed after culture.
• MIC - lowest concentration inhibiting visible growth; interpreted against CLSI/EUCAST breakpoints, not in isolation.
• Time- vs concentration-dependent killing - β-lactams need T>MIC (frequent/extended dosing); aminoglycosides need high Cmax/MIC (once-daily dosing).
• AWaRe - WHO Access/Watch/Reserve grouping; Access drugs should form the bulk of consumption.
• NTEP regimen - 2 months HRZE + 4 months HRE daily, weight-band FDCs, pyridoxine with isoniazid.
• Ethambutol - optic neuritis; isoniazid - neuropathy and hepatitis; rifampicin - orange urine and CYP3A4 induction.
• TLD - tenofovir + lamivudine + dolutegravir, NACO's usual first-line ART, free in public ART centres.
• ACT + primaquine - falciparum malaria; vivax needs 14-day primaquine after G6PD screening.
• Febrile neutropenia - ANC <500/mm³ plus fever; broad-spectrum antibiotic within one hour is the single most important act.
• BSA dosing - cytotoxics dosed in mg/m² (Mosteller/DuBois); carboplatin by AUC via Calvert.
• Cumulative dose limits - doxorubicin ~450-550 mg/m² (cardiotoxicity), bleomycin ~400 units (pulmonary fibrosis).
• Mesna, leucovorin, dexrazoxane - uroprotection, folate rescue, cardioprotection respectively.
• Tumour lysis syndrome - high K⁺, PO₄³⁻, uric acid with low Ca²⁺; hydration plus allopurinol or rasburicase.
• Vincristine is never intrathecal - intrathecal administration is fatal; a core medication-safety question.
• Metformin - first-line type 2 agent; stop if eGFR <30 and withhold around contrast imaging.
• SGLT2 inhibitors / GLP-1 RA - preferred with ASCVD, heart failure or CKD irrespective of HbA1c.
• Levothyroxine - 1.6 µg/kg/day, fasting, separated from calcium/iron, TSH rechecked after 6-8 weeks.
• Steroid taper - needed after about 2-3 weeks of supraphysiological dosing to avoid adrenal crisis.

Formulas and examples

Example 1 — BSA and chemotherapy dose. A woman with breast cancer is 155 cm, 58 kg, prescribed paclitaxel 175 mg/m².

• BSA = √(155 × 58 / 3600) = √(8990/3600) = √2.4972 = 1.58 m²
• Dose = 175 × 1.58 = 276.5 mg, rounded per policy to 275 mg in 500 mL normal saline over 3 h.
• Pre-medication: dexamethasone, an H1 and an H2 blocker to prevent the Cremophor hypersensitivity reaction.

Example 2 — Calvert carboplatin dose. Male, 60 years, 70 kg, serum creatinine 1.1 mg/dL, target AUC 5.

• CrCl = (140 − 60) × 70 / (72 × 1.1) = 5600/79.2 = 70.7 mL/min
• Dose = 5 × (70.7 + 25) = 5 × 95.7 = 478.5 mg ≈ 480 mg.
• If the same patient were female: CrCl = 70.7 × 0.85 = 60.1 → dose = 5 × 85.1 = 425.5 mg ≈ 425 mg. Renal function, not body size, drives carboplatin dosing.

Example 3 — Insulin initiation and correction dose. Type 1 patient, 60 kg, started on 0.6 U/kg/day basal-bolus.

• TDD = 0.6 × 60 = 36 U/day; basal (glargine) 50% = 18 U at night; bolus 18 U split as 6 U before each of three meals.
• Correction factor = 1800/36 = 50 mg/dL per unit; insulin-to-carb ratio = 500/36 = 13.9 ≈ 14 g per unit.
• Pre-meal glucose 250 mg/dL, target 120: correction = (250 − 120)/50 = 2.6 ≈ 2.5 U extra, plus the meal bolus.

Example 4 — HbA1c interpretation. HbA1c 9.4%.

• eAG = 28.7 × 9.4 − 46.7 = 269.78 − 46.7 = 223.1 mg/dL, so average glucose is far above the <154 mg/dL that corresponds to 7%.
• At this level, dual or triple oral therapy alone rarely suffices: add basal insulin or a GLP-1 RA, review adherence, screen for infection/TB, and recheck HbA1c in 3 months (it reflects ~8-12 weeks of glycaemia, so no sooner).

Example 5 — DKA sodium, osmolality and potassium. Na⁺ 128 mEq/L, glucose 720 mg/dL, BUN 28 mg/dL, K⁺ 5.6 mEq/L.

• Corrected Na⁺ = 128 + 1.6 × [(720 − 100)/100] = 128 + 1.6 × 6.2 = 128 + 9.92 = 137.9 mEq/L — the apparent hyponatraemia is dilutional.
• Osmolality = 2(128) + 720/18 + 28/2.8 = 256 + 40 + 10 = 306 mOsm/kg.
• Insulin infusion 0.1 U/kg/h; hold potassium because K⁺ >5.2, recheck in 2 h — total body potassium is depleted and will fall sharply once insulin starts.

Where it is used

• Hospital clinical pharmacy: ward rounds in ICU, oncology day-care and medicine units — dose verification, TDM, antibiotic de-escalation, insulin titration, discharge counselling (AIIMS, PGIMER, CMC Vellore, Tata Memorial, Apollo, Manipal, Amrita).
• Antimicrobial stewardship and infection-control teams: antibiotic policy drafting, consumption audit (DDD/100 bed-days), culture-report follow-up under the National Action Plan on AMR; NABH accreditation requires a documented antibiotic policy.
• Oncology pharmacy and cytotoxic reconstitution units: protocol-based order verification, aseptic compounding in biosafety cabinets, extravasation and spill management, chemotherapy waste handling.
• National programmes: NTEP (DOT and DR-TB regimens, adverse-event monitoring under aDSM), NACO ART centres, NVBDCP malaria treatment, NPCDCS diabetes clinics.
• Pharmaceutical industry: medical information, medical science liaison, medical writing, pharmacovigilance case processing and PSUR writing, clinical research associate roles in oncology/endocrine trials — common first jobs for Pharm.D graduates.
• Community pharmacy and diabetes education: insulin technique, glucometer use, foot care, Schedule H1 register upkeep, counselling against self-medication with antibiotics.

Interview questions

• Q: How do you choose an empirical antibiotic? A: From the likely site and pathogen, severity, patient factors (renal function, allergy, pregnancy, prior antibiotics) and the hospital's own sensitivity data — then narrow on culture within 48-72 hours.
• Q: Why is vancomycin monitored by AUC rather than trough alone? A: Efficacy correlates with AUC₂₄/MIC around 400-600, and trough-only targets of 15-20 mg/L drove unnecessary nephrotoxicity.
• Q: Why is pyridoxine given with isoniazid? A: Isoniazid increases pyridoxine excretion and inhibits its activation, causing peripheral neuropathy, which prophylactic pyridoxine prevents.
• Q: A patient on rifampicin becomes pregnant on oral contraceptives — explain. A: Rifampicin is a potent CYP3A4 and P-glycoprotein inducer and accelerates contraceptive steroid metabolism, so a non-hormonal or alternative method must be advised.
• Q: Why avoid fluoroquinolones for routine respiratory infection in India? A: They partially treat and mask undiagnosed tuberculosis and promote fluoroquinolone resistance in *M. tuberculosis*, compromising second-line TB therapy.
• Q: Why is a *vivax* patient screened for G6PD deficiency? A: Primaquine, needed for radical cure of liver hypnozoites, causes acute haemolysis in G6PD-deficient individuals.
• Q: How is carboplatin dosed and why is it different? A: By the Calvert formula using target AUC and GFR, because carboplatin clearance is almost entirely renal, making renal function a better predictor than body surface area.
• Q: What checks do you make before releasing a chemotherapy order? A: Confirmed diagnosis and protocol, cycle number and interval, recalculated BSA and dose, ANC/platelets and renal/hepatic function, cumulative anthracycline dose, pre-medication, diluent and infusion time, and vesicant route.
• Q: Why must vincristine never be given intrathecally? A: It causes fatal ascending encephalomyelopathy; it is labelled "for intravenous use only" and is kept and dispensed separately from intrathecal drugs.
• Q: In DKA, when do you add dextrose to the fluids? A: When glucose falls below about 200-250 mg/dL, so the insulin infusion can continue to clear ketones without causing hypoglycaemia.
• Q: Which antidiabetic would you prefer for a type 2 patient with heart failure? A: An SGLT2 inhibitor, which reduces heart-failure hospitalisation and slows CKD progression; pioglitazone and saxagliptin are best avoided.
• Q: Why is levothyroxine taken on an empty stomach, away from calcium? A: Food, calcium, iron, soy and proton-pump inhibitors reduce its absorption, so separation by 30-60 minutes from food and about 4 hours from calcium or iron keeps the dose effective.
• Q: A patient on long-term prednisolone has surgery — what is your advice? A: Do not stop abruptly; the adrenal axis is suppressed, so continue and give stress-dose parenteral hydrocortisone perioperatively to prevent adrenal crisis.

Common mistakes

• Treating culture growth as infection — colonisation and contamination (especially a single coagulase-negative *Staphylococcus* blood culture) are over-treated.
• Giving a broad-spectrum antibiotic for a full course without reviewing at 48-72 h, or not switching IV to oral when the patient is eating and afebrile.
• Confusing MIC with dose, or assuming a lower MIC drug is "stronger" across different species and breakpoints.
• Calculating BSA or Calvert dose with mixed units (height in metres, creatinine in µmol/L) — recompute, and note that carboplatin uses GFR, not CrCl-adjusted body weight.
• Forgetting cumulative-dose ceilings and nadir timing, so chemotherapy is given on a low ANC or beyond the anthracycline limit.
• Starting potassium in DKA before confirming K⁺ <5.2 mEq/L and urine output, or stopping the insulin infusion as soon as glucose normalises while ketosis persists.
• Mixing up corticosteroid potencies (dexamethasone is ~25-30 times hydrocortisone) and stopping long-term steroids abruptly.
• Quoting old programme names and regimens (RNTCP for NTEP, three-drug ART or injection-based MDR-TB regimens) — these guidelines are revised often and must be checked against the current national document.

Related topics

Pharmacotherapeutics: cardiovascular, respiratory and renal disorders · Pharmacotherapeutics: neurological, psychiatric and gastrointestinal disorders · Clinical pharmacokinetics and therapeutic drug monitoring · Pharmacovigilance and adverse drug reaction reporting · Clinical pharmacy practice: ward rounds, medication reconciliation and patient counselling · Medicinal chemistry and pharmacology of antimicrobials and anticancer agents.