Benzylpenicillin (Penicillin G)

DRUG NAME: Benzylpenicillin (Penicillin G)

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Therapeutic Class: Antibiotic

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Subclass: Natural Penicillin (Beta-Lactam — Penicillinase-Susceptible)

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Schedule (India):

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Route(s):

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Biosimilar Status:

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Formulations Available in India:

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• Rheumatic fever/RHD secondary prophylaxis — patients unable to receive 3-weekly or 4-weekly injections, leading to recurrent rheumatic fever episodes and RHD progression
• Syphilis treatment — particularly congenital syphilis prevention (WHO elimination target)
• National programmes — NVHCP (National Programme for Prevention and Control of RHD) and syphilis screening programmes

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PHARMACOKINETICS

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ADULT INDICATIONS + DOSING — FOR CLINICIAN USE ONLY

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1. Always verify the SALT FORM before administration. Crystalline (sodium/potassium) penicillin, procaine penicillin, and benzathine penicillin are NOT interchangeable and have different routes, dosing, and indications. IV administration of procaine or benzathine penicillin is FATAL.
2. Always enquire about penicillin allergy before administration. True penicillin allergy (IgE-mediated anaphylaxis) is a contraindication to ALL penicillin formulations. Cross-reactivity with cephalosporins exists (~1–2% with modern cephalosporins).
3. Dose is expressed in units (IU), NOT milligrams, for all salt forms. The Indian convention of ”lakh units“ is used alongside international ”Mega Units (MU)“ throughout this monograph.
4. Time-dependent killing: Frequent dosing (every 4–6 hours) of crystalline penicillin is essential for efficacy — do NOT extend intervals for convenience unless renal dose adjustment is specifically indicated.

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Primary Indications (Approved / Standard in India)

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1. When to prefer this drug over alternatives: Benzathine penicillin IM is the ONLY recommended drug for RF secondary prophylaxis in India. It is superior to oral penicillin V because: (a) 100% bioavailability (no absorption variability); (b) guaranteed compliance (administered by healthcare worker); © long duration of action (3–4 weeks per injection); (d) oral penicillin V requires daily adherence for years — adherence rates in Indian studies are abysmally low (<30% in many settings). ℹ️ Oral penicillin V (250 mg BD) is an alternative ONLY when benzathine penicillin is unavailable or absolutely refused by the patient. Oral erythromycin (250 mg BD) is a second-line alternative for penicillin-allergic patients.
2. When NOT to use: ⛔ Confirmed IgE-mediated penicillin allergy (history of anaphylaxis, angioedema, urticaria within 1 hour of penicillin). In these patients, use oral erythromycin 250 mg BD (or azithromycin 250 mg daily — used in some Indian centres, though evidence is limited). ⚠️ Do NOT substitute with cephalosporins for RF prophylaxis — cross-reactivity risk (~1–2%) and no established evidence for RF prophylaxis with cephalosporins.
3. NLEM India status: ✅ Benzathine penicillin injection is listed in NLEM India 2022 — Section 6.2 (Antibacterials — Beta-lactam medicines). Both 6 lakh unit and 12 lakh unit vials are listed.
4. Time to response: Not applicable in the traditional sense — this is prophylaxis, not treatment. Effectiveness is measured by prevention of recurrent RF episodes. With regular 3-weekly prophylaxis, the recurrence rate of RF drops from ~20% per year (untreated) to <1% per year.
5. Criteria for treatment failure: Recurrent RF episode despite regular prophylaxis suggests: (a) non-adherence (missed injections); (b) 4-weekly interval may be insufficient — switch to 3-weekly; © inadequate injection technique (drug not deposited deep IM — superficial injection leads to faster absorption and shorter duration); (d) very rarely, penicillin-resistant GAS (not documented as clinically significant for RF prophylaxis to date).
6. Mandatory baseline investigations:
   • MANDATORY: Echocardiography (to document baseline valvular status and severity of RHD — essential for determining duration of prophylaxis and surgical planning).
   • RECOMMENDED: ASO titre, CRP/ESR (if acute RF episode is being evaluated); throat swab culture (to identify Group A Streptococcus carriage).
   • MANDATORY before FIRST injection: Enquire specifically about penicillin allergy. Have adrenaline (epinephrine) injection 1:1000 and anaphylaxis management kit available at the injection site.
7. Specialist initiation: Initial diagnosis and classification of RF/RHD should be by a physician or cardiologist (Jones Criteria for diagnosis; echocardiography for classification). Ongoing monthly injections can be administered at PHC/CHC level by trained staff — this is the model promoted by NVHCP. RF prophylaxis should NOT be limited to tertiary centres.
8. Indian guideline source: ICMR Guidelines on RF/RHD Prevention (2008 — still referenced; updated practice incorporates 3-weekly regimen); API Textbook of Medicine (current edition) — Chapter on Rheumatic Fever and RHD; NVHCP (National Programme for Prevention and Control of RHD) operational guidelines; Indian Heart Journal — position statements on RF prophylaxis.
9. Key disease-specific safety warning: ⚠️ Anaphylaxis risk: Benzathine penicillin injections carry a small but non-zero risk of anaphylaxis (~0.01–0.05% per injection). Given that patients receive injections every 3–4 weeks for years or decades, the cumulative exposure is significant. Every injection centre MUST have: (a) adrenaline (epinephrine) 1:1000 ampoule and syringe ready; (b) trained staff who can recognise and manage anaphylaxis; © at least 30 minutes of post-injection observation before the patient leaves. ⚠️ Hoigné reaction (pseudo-anaphylaxis): A non-allergic reaction specific to procaine-containing and benzathine penicillin injections — presents with acute fear of death, visual/auditory disturbances, agitation, bizarre behaviour, tachycardia, and sometimes seizures. It is NOT IgE-mediated, is NOT fatal (unlike true anaphylaxis), and resolves spontaneously within 15–30 minutes with supportive care (reassurance, benzodiazepine for agitation). It is thought to be caused by microemboli of the depot suspension reaching the CNS. Differentiation from true anaphylaxis is critical — Hoigné reaction does NOT have: urticaria, angioedema, bronchospasm, or hypotension. Do NOT administer adrenaline for Hoigné reaction unless anaphylaxis features are present.
10. Common dose adjustment scenarios:
    • Renal impairment: Not applicable — benzathine penicillin IM achieves very low serum levels that are well below the threshold for penicillin neurotoxicity. No dose adjustment needed for renal impairment in the prophylaxis context.
    • Hepatic impairment: No adjustment needed.
    • Body weight ≥27 kg (children transitioning to adult dose): Use the full 12 lakh unit (1.2 MU) dose. Children <27 kg: use 6 lakh units (600,000 IU). See Paediatric Dosing.
    • Pregnancy: Benzathine penicillin is safe in pregnancy (Category B). RF prophylaxis must NOT be interrupted during pregnancy.

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1. When to prefer over alternatives: Benzathine penicillin is the ONLY recommended first-line treatment for early syphilis (NACO, WHO, CDC guidelines). There is NO equivalent alternative for efficacy and simplicity. For penicillin-allergic non-pregnant patients: doxycycline 100 mg BD × 14 days is the alternative. For penicillin-allergic pregnant women: penicillin desensitisation is recommended (not avoidance) — no alternative to penicillin has proven efficacy for preventing congenital syphilis.
2. When NOT to use: ⛔ Confirmed penicillin allergy (IgE-mediated). ⛔ Do NOT use benzathine penicillin for neurosyphilis or ocular syphilis — inadequate CSF and ocular penetration (see Indication 4 below).
3. NLEM India status: ✅ NLEM-listed (benzathine penicillin injection).
4. Time to response: Chancre healing: 1–3 weeks. Rash resolution: 3–6 weeks. Serological response (RPR/VDRL titre decline): ≥4-fold decline within 6–12 months (considered adequate response). Slower decline does not necessarily indicate treatment failure — it may indicate late treatment or re-infection.
5. Treatment failure criteria: Failure of RPR/VDRL titre to decline ≥4-fold within 6–12 months, OR a ≥4-fold rise in titre after initial decline. Consider: (a) re-infection (most common cause of apparent ”failure“); (b) undiagnosed neurosyphilis (lumbar puncture indicated); © HIV co-infection (may have delayed serological response). Re-treat with benzathine penicillin 2.4 MU IM weekly × 3 doses.
6. Baseline investigations:MANDATORY: Confirm diagnosis (darkfield microscopy if chancre available; RPR/VDRL + confirmatory treponemal test [TPHA/FTA-ABS]). MANDATORY: HIV testing (all syphilis patients must be tested for HIV — NACO guidelines). RECOMMENDED: CSF examination if neurological symptoms, ocular symptoms, treatment failure, or HIV with CD4 <350.
7. Specialist initiation: Not required for early syphilis. Primary care/PHC prescribing is appropriate. NACO/NACP-designated STI clinics handle diagnosis and treatment.
8. Indian source: NACO (National AIDS Control Organisation) STI Treatment Guidelines (current edition); WHO Guidelines on Syphilis Treatment (2016); API Textbook of Medicine.
9. Safety warning: ⚠️ Jarisch-Herxheimer reaction (JHR): Occurs in 10–35% of patients treated for early syphilis (especially secondary syphilis). Onset: 2–8 hours after first penicillin injection. Presents as: acute fever (38–40°C), rigors, headache, myalgia, tachycardia, flushing, worsening of rash, and hypotension (rarely). Caused by release of treponemal endotoxin-like lipoproteins from dying organisms — NOT an allergic reaction. Usually self-limiting (12–24 hours). Management: Paracetamol, hydration, reassurance. Does NOT require discontinuation of penicillin treatment. ⚠️ In pregnant women, JHR can cause uterine contractions and fetal distress — treat syphilis in pregnancy with obstetric monitoring available.
10. Dose adjustment: No renal or hepatic adjustment needed for single-dose benzathine penicillin.

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• Always rule out neurosyphilis (by LP) before treating late syphilis with benzathine penicillin — if neurosyphilis is present, benzathine penicillin is INADEQUATE (see Indication 4).
• Serological follow-up: RPR/VDRL at 6, 12, and 24 months post-treatment. A ≥4-fold decline indicates adequate response (may take longer than for early syphilis).

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1. When to prefer: IV crystalline penicillin is the only recommended treatment for neurosyphilis and ocular syphilis (NACO, WHO, CDC). ⛔ Benzathine penicillin does NOT achieve adequate CSF or ocular levels — it must NEVER be used for neurosyphilis.
2. NLEM status: Crystalline penicillin is NLEM-listed.
3. Time to response: Clinical improvement (resolution of meningitis symptoms, stabilisation of cranial neuropathies) within days to weeks. CSF normalisation (cell count, protein): 6–12 months. Repeat LP at 6 months post-treatment to confirm CSF improvement.
4. Baseline investigations:MANDATORY: Lumbar puncture (CSF cell count, protein, glucose, CSF-VDRL); HIV testing; RPR/VDRL titre. RECOMMENDED: MRI brain if focal neurological deficits.
5. Treatment failure: CSF-VDRL remains positive, or CSF pleocytosis persists at 6 months — consider retreatment with the same IV regimen. If HIV-positive, response may be slower.
6. Indian source: NACO STI Treatment Guidelines; API Textbook of Medicine.
7. Safety warning: ⚠️ JHR can cause acute worsening of neurological symptoms (seizures, cranial nerve palsies, stroke-like episodes) — monitor in hospital. ⚠️ At high IV doses (18–24 MU/day), monitor for penicillin neurotoxicity (see Serious Adverse Effects) — especially in patients with concurrent renal impairment.

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1. When to prefer over alternatives: Benzylpenicillin is the narrowest-spectrum effective agent for meningococcal meningitis and is preferred over ceftriaxone once meningococcal aetiology is confirmed — it minimises disruption of normal flora and collateral resistance pressure. However, ceftriaxone 2 g IV BD (or cefotaxime 2 g IV every 4–6 hours) is the standard empirical therapy for suspected bacterial meningitis in India (covers meningococcal, pneumococcal, and H. influenzae). Switch to benzylpenicillin once culture/sensitivity confirms meningococcus with penicillin MIC ≤0.06 mcg/mL (susceptible).
2. When NOT to use: ⚠️ Empirically — do NOT use benzylpenicillin as empirical meningitis therapy without susceptibility data. In India, pneumococcal meningitis (which may have intermediate or full penicillin resistance) is common, and benzylpenicillin alone would be inadequate. Empirical therapy must be ceftriaxone ± vancomycin (for suspected penicillin-resistant pneumococcus) ± ampicillin (for Listeria in elderly/immunocompromised).
3. NLEM status: ✅ NLEM-listed.
4. Time to response: Clinical improvement (fever defervescence, improving consciousness) expected within 48–72 hours. If no improvement by 48 hours, reassess: repeat LP, broaden coverage, consider alternative diagnoses (TB meningitis is a common differential in India).
5. Baseline investigations:MANDATORY: LP before antibiotics if possible (CSF Gram stain, culture, protein, glucose, cell count); blood cultures × 2 sets; CBC, CRP, electrolytes, renal function. Do NOT delay antibiotics for LP if the patient is critically ill — give antibiotics first, then LP as soon as feasible.
6. Specialist initiation: Initial management should be by a physician, intensivist, or paediatrician experienced in meningitis management. PHC-level initiation of empirical antibiotics (ceftriaxone) before referral is appropriate and recommended.
7. Indian source: ICMR guidelines on bacterial meningitis management; API Textbook of Medicine; NCDC meningococcal disease outbreak response protocol.
8. Safety warning: ⚠️ Monitor serum electrolytes (sodium content of crystalline penicillin — hypernatraemia risk at high doses). ⚠️ Monitor for seizures (both from meningitis and from potential penicillin neurotoxicity at high doses in patients with concurrent renal impairment).
9. Dose adjustment in renal impairment: Reduce dose if eGFR <30 (see RENAL ADJUSTMENT). ⚠️ In meningitis, dose reduction must balance the risk of neurotoxicity (from accumulation) against the risk of therapeutic failure (from subtherapeutic CSF levels). Consult infectious disease specialist.

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1. When to prefer: Benzylpenicillin is the gold standard for penicillin-susceptible streptococcal IE — highest published cure rates (~98% microbiological cure for fully susceptible strains). Preferred over ceftriaxone when patient is hospitalised with reliable IV access. Ceftriaxone 2 g IV OD × 4 weeks is an alternative for outpatient parenteral antibiotic therapy (OPAT) — possible in select stable patients.
2. When NOT to use: ⛔ Penicillin MIC >0.5 mcg/mL — treat as enterococcal endocarditis protocol (ampicillin + gentamicin or ampicillin + ceftriaxone). ⛔ Staphylococcal IE — requires anti-staphylococcal agents (cloxacillin, vancomycin). ⛔ Enterococcus IE — requires ampicillin (not penicillin G) + gentamicin/ceftriaxone synergy.
3. NLEM status: ✅ NLEM-listed.
4. Time to response: Blood cultures should become negative within 48–72 hours of initiating appropriate therapy. Persistent positive cultures after 7 days suggest: perivalvular abscess, wrong antibiotic, wrong diagnosis, or metastatic infection.
5. Baseline investigations:MANDATORY: ≥3 sets blood cultures (before antibiotics); echocardiography (TTE first; TOE if TTE inconclusive or prosthetic valve); CBC, CRP, ESR, renal function, urinalysis (microscopic haematuria). RECOMMENDED: Duke Criteria assessment for definitive diagnosis.
6. Specialist initiation:Mandatory — IE management requires a cardiologist and infectious disease specialist (or experienced physician). Surgery consultation for all patients.
7. Indian source: API Textbook of Medicine — IE chapter; AHA/ESC IE Guidelines (adapted for Indian practice); AIIMS IE protocols.
8. Safety warning: ⚠️ Monitor renal function and gentamicin trough levels (target <1 mcg/mL) to prevent aminoglycoside nephrotoxicity and ototoxicity. ⚠️ Monitor for penicillin neurotoxicity (seizures) at high doses — especially if renal function declines during the prolonged treatment course.
9. Dose adjustment: Reduce crystalline penicillin dose if eGFR <30 mL/min (see RENAL ADJUSTMENT). Adjust gentamicin per renal function and TDM.

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• This is a SURGICAL EMERGENCY. Refer to surgery immediately. Antibiotics support, but do not replace, debridement.
• Clostridium perfringens remains universally susceptible to penicillin. No resistance has been documented.
• Hyperbaric oxygen therapy (HBO) is an adjunct at select Indian tertiary centres — benefit is debated but may be considered if available.
• Indian source: API Textbook of Medicine; surgical textbooks (SRB’s Manual of Surgery, Bailey & Love).

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• ⚠️ Pneumococcal penicillin resistance in India: The rate of penicillin-non-susceptible S. pneumoniae (PNSP) in India is approximately 5–15% (varies by region and study). However, for non-meningeal pneumococcal infections (pneumonia, bacteraemia), the revised CLSI breakpoints (2008) set the susceptible breakpoint at MIC ≤2 mcg/mL (much higher than for meningitis — ≤0.06). Most ”intermediate resistance“ pneumococci by old breakpoints are actually susceptible by current non-meningeal breakpoints. High-dose IV penicillin (2 MU every 4 hours) achieves serum levels well above MIC 2 mcg/mL.
• Empirical therapy for CAP in India (API Textbook, ICMR guidelines) is amoxicillin (oral, for mild CAP) or ceftriaxone + azithromycin (IV, for moderate-severe CAP). Benzylpenicillin is used as definitive therapy once culture confirms susceptible pneumococcus — narrower spectrum, lower resistance pressure.

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Secondary Indications — Adults Only (Off-label)

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PAEDIATRIC DOSING (Specialist Only)

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• ⚠️ SALT FORM VERIFICATION IS CRITICAL IN PAEDIATRICS. The consequences of administering the wrong salt form are amplified in children. Inadvertent IV administration of benzathine or procaine penicillin in a child can be fatal. Always verify the vial label at the bedside.
• Safety monitoring requirements specific to paediatric use:
  • Monitor IV site for extravasation and phlebitis (crystalline penicillin is irritant to veins — particularly in small paediatric veins)
  • Monitor for seizures at high IV doses — children with renal impairment, CNS infections, or dehydration are at higher risk of penicillin neurotoxicity
  • Monitor serum electrolytes at high IV doses — sodium load (from sodium salt) can be significant in small infants
  • ⚠️ Monitor for hyperkalaemia if using the potassium salt (less common in India but may be supplied) — particularly in neonates and infants with immature renal function
  • ⚠️ Anaphylaxis preparedness must be available before any penicillin injection — adrenaline (epinephrine) dose in children: 0.01 mL/kg of 1:1000 (adrenaline 1 mg/mL) IM, maximum 0.3 mL in children <6 years, 0.5 mL in children ≥6 years
  • For benzathine penicillin IM: observe for 30 minutes after injection for anaphylaxis and Hoigné reaction (see adult section — Hoigné reaction can also occur in children, presenting as acute distress, inconsolable crying, and bizarre behaviour)
• Minimum age limits:
  • Crystalline penicillin (IV/IM): Can be used from birth (including preterm neonates) — see Neonatal Dosing below
  • Procaine penicillin (IM): Generally used from birth; some guidelines avoid in preterm neonates due to concerns about procaine toxicity (seizures from procaine component) — crystalline penicillin is preferred in neonates
  • Benzathine penicillin (IM): Used from infancy (>1 month) for RF prophylaxis and congenital syphilis prevention; can be used in neonates (see congenital syphilis dosing below)
• Minimum weight:
  • Benzathine penicillin RF prophylaxis dose transition: <27 kg → 6 lakh units (600,000 IU); ≥27 kg → 12 lakh units (1.2 MU)
  • For all other indications, dosing is weight-based (units/kg)
• Formulation suitability for children:
  • Crystalline penicillin (powder for injection): Suitable — allows accurate weight-based dose calculation after reconstitution. Available in 5 lakh and 10 lakh unit vials (appropriate for paediatric dosing). Requires reconstitution — see Reconstitution section.
  • Procaine penicillin (suspension for IM): Suitable for IM injection in children. ⚠️ Large-volume IM injections are painful — divide dose between two injection sites if volume exceeds 1 mL in infants or 2 mL in older children.
  • Benzathine penicillin (suspension for IM): Suitable for children ≥1 month. ⚠️ The suspension is viscous and requires a 21G or larger needle and slow, deep IM injection into a large muscle mass (anterolateral thigh in infants <2 years; gluteal/ventrogluteal in children ≥2 years). The injection is painful — distraction techniques, EMLA cream (applied 60 minutes prior), and caregiver support are recommended.
  • No oral formulation exists — this is a significant practical limitation. For children who need oral antibiotic step-down, switch to oral amoxicillin (suspension available in India — palatable formulations widely available) or oral phenoxymethylpenicillin (Penicillin V) (less palatable — bitter taste; suspension available but less commonly stocked in India; tablet formulation available for older children).
• Palatability: Not applicable — no oral formulation. However, IM benzathine penicillin injections are notoriously painful (viscous suspension, large volume, deep IM site) — this is a major adherence barrier for RF prophylaxis in children. Strategies to improve adherence: EMLA cream before injection, use of 21G 1.5-inch needle, slow injection (≥2 minutes), warming the vial to room temperature before injection, and psychological support.
• Age-specific pharmacokinetic differences affecting dosing:
  • Neonates (especially preterm): Markedly prolonged half-life (see Population PK in Part 1). Require REDUCED dosing frequency (every 8–12 hours in preterm neonates instead of every 4–6 hours in older children).
  • Infants (1–12 months): Half-life approaches adult values by 3–6 months. Standard weight-based dosing with every-4–6-hour frequency is appropriate.
  • Children (1–12 years): Pharmacokinetics similar to adults on a per-kg basis. Weight-based dosing applies.
  • Adolescents (≥12 years or ≥40 kg): Transition to adult dosing.

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• Half-life of benzylpenicillin in neonates is gestational age-dependent:
  • Preterm <29 weeks gestation (first week of life): t½ ~6–10 hours
  • Preterm 29–36 weeks (first week of life): t½ ~4–6 hours
  • Term ≥37 weeks (first week of life): t½ ~2–3 hours
  • By day 14 of life (term neonate): t½ ~1.5 hours (approaching infant values)
• Immature renal tubular secretion (OAT1/OAT3 transporters) is the primary reason for prolonged half-life
• Dosing intervals must be EXTENDED in preterm neonates to avoid accumulation

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Primary Indications — Paediatric (Approved / Standard in India)

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1. When to prefer: Benzathine penicillin IM is the ONLY recommended prophylaxis in children (same rationale as adults — guaranteed compliance, 100% bioavailability).
2. When NOT to use: True penicillin allergy (IgE-mediated). Alternative: oral erythromycin (20 mg/kg/day in 2 divided doses, max 250 mg BD). Penicillin allergy testing and desensitisation may be considered at tertiary centres.
3. NLEM status: ✅ NLEM-listed.
4. Specialist initiation: Diagnosis of RF (Jones Criteria) should be confirmed by a paediatrician or paediatric cardiologist. Echocardiography is MANDATORY for all children with suspected RF. Ongoing injections can be administered at PHC/CHC level or school health clinics — NVHCP promotes community-level delivery.
5. Indian source: IAP Guidelines on RF/RHD (2008, updated practice); NVHCP; API Textbook.
6. Key safety warning: ⚠️ Injection pain is a major adherence barrier in children. Strategies: EMLA cream 60 minutes before injection, use of a 21G needle (not smaller — smaller gauges increase injection time and may clog with viscous suspension), warm the vial to room temperature, inject slowly over ≥2 minutes, use the Z-track technique to reduce leakage, distraction techniques (play therapist, cartoons, parental comfort). Document injection site and rotate between buttocks. ⚠️ Post-injection observation for 30 minutes is MANDATORY in children.
7. Dose adjustment: No renal or hepatic adjustment needed for benzathine penicillin prophylaxis doses.

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Secondary Indications — Paediatric (Off-label)

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MISSED DOSE / DELAYED DOSE GUIDANCE

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• No withdrawal syndrome — can be stopped and restarted at any time.
• No rebound infection — stopping prophylaxis increases the risk of new RF episodes or new GAS infection, but this is a loss of prophylactic protection, not a rebound phenomenon.
• No re-titration needed — the drug can be resumed at the previous dose after any duration of non-adherence.
• Not a biologic — no immunogenicity concern.

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RECONSTITUTION / ADMINISTRATION QUICK REFERENCE (For Nurses & Clinical Staff)

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Example: A 12 kg child with suspected meningococcal meningitis. Dose prescribed: 50,000 units/kg/dose IV every 4 hours.

• • Required dose per administration = 12 × 50,000 = 600,000 units (6 lakh units)
  • Using a 10 lakh unit (1 MU) vial reconstituted with 4 mL SWFI (= ~200,000 units/mL):
    • Volume to draw = 600,000 / 200,000 = 3 mL
  • Dilute 3 mL in 20–50 mL NS and infuse over 15–30 minutes via Soluset/burette.
  • Administer every 4 hours (6 times/day = total 3,600,000 units/day = 36 lakh units/day).

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• Labelled with the drug name, concentration, date, and time of reconstitution
• Stored in the refrigerator (2–8°C)
• Used within 24 hours (refrigerated) or discarded
• ⚠️ For neonatal use: use a fresh vial for each dose — do NOT use partially used vials (contamination risk in immunocompromised neonates).

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RENAL ADJUSTMENT

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• Continuous IV infusion of crystalline penicillin is the preferred approach in ARC — maintains 100% fT>MIC regardless of clearance rate.
• Alternatively, increase dosing frequency to every 3–4 hours (from every 4 hours) if using intermittent dosing.
• Do NOT simply increase the individual dose size (increases peak but does not extend the time above MIC — pharmacodynamically inefficient for time-dependent antibiotics).
• Formal TDM for penicillin is not routinely available in India but is performed at select centres.

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HEPATIC ADJUSTMENT

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CONTRAINDICATIONS

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1. If history is vague (”my mother says I had a rash to penicillin as a child“): This is very common in Indian OPD. The vast majority of such patients are NOT truly penicillin-allergic. If the indication is critical (RF prophylaxis, syphilis in pregnancy), consider formal penicillin skin testing at a tertiary centre. If skin testing is negative, penicillin can be safely administered.
2. If history is convincing (documented anaphylaxis, angioedema, urticaria within 1 hour): Treat as true penicillin allergy. Avoid ALL penicillins. Use appropriate alternatives (erythromycin for RF prophylaxis; doxycycline for syphilis; ceftriaxone for meningitis/endocarditis — with first dose under observation).
3. If penicillin is ESSENTIAL and no alternative is adequate (e.g., syphilis in a pregnant woman with penicillin allergy): ⚠️ Penicillin desensitisation is indicated. This involves administering incrementally increasing doses of oral or IV penicillin over 3–4 hours in an ICU or monitored setting with full anaphylaxis management capability. Desensitisation protocols are available at AIIMS, CMC Vellore, PGI, and select tertiary centres. The desensitisation provides temporary tolerance — the patient must receive penicillin continuously after desensitisation (if treatment is interrupted, desensitisation is lost and must be repeated).

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CAUTIONS

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PREGNANCY

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LACTATION

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ELDERLY

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MAJOR DRUG INTERACTIONS

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MODERATE DRUG INTERACTIONS

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COMMON ADVERSE EFFECTS

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SERIOUS ADVERSE EFFECTS

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MONITORING REQUIREMENTS

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• Refractory endocarditis with suspected subtherapeutic levels
• ICU patients with augmented renal clearance (ARC) where continuous infusion is being used
• Neonates with renal impairment receiving high-dose penicillin

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• Acute infection courses (5–14 days): Monitoring can be discontinued once the course is completed and clinical recovery is confirmed.
• Prolonged courses (endocarditis — 4–6 weeks): Continue weekly monitoring throughout the course and for 1–2 weeks after completion (delayed adverse effects — interstitial nephritis, haemolytic anaemia).
• RF prophylaxis (years to lifelong): Annual echocardiography and clinical assessment at each injection visit — indefinitely.

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PATIENT COUNSELLING

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• For RF prophylaxis (benzathine penicillin injection): ”This injection protects your heart. You had a disease called rheumatic fever that can damage your heart valves. This injection, given every 3 weeks, prevents the fever from coming back and protects your heart from further damage. It is one of the most important medicines you will ever receive.“
• For syphilis (benzathine penicillin injection): ”This injection treats a sexually transmitted infection called syphilis. It is the best medicine for this infection and works with just one injection in most cases.“
• For serious infection (crystalline penicillin IV): ”This medicine is being given through your vein to fight a serious infection in your body. It needs to be given every few hours, day and night, to keep the medicine levels high enough to kill the germs.“

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• ”This medicine is given as an injection — either into a vein (IV drip) or into the muscle of your buttock or thigh. There is no tablet or syrup form.“
• For RF prophylaxis: ”You need to come to the clinic every 3 weeks (21 days) for your injection. Mark the dates on a calendar or set a phone reminder. Do not skip or delay injections — even one missed injection puts your heart at risk.“

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• RF prophylaxis (benzathine penicillin): ”If you miss your injection date, come as soon as possible — even if it is a few days late. The injection still works. Then resume your regular 3-week schedule. If you have missed many injections (more than 1 month), come to the clinic as soon as possible and tell the doctor. You may need a heart check-up.“
• IV penicillin (hospital): ”The nurses will give your medicine at the correct times. If you notice that an injection has been delayed or missed, tell the nurse or doctor immediately.“

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• Difficulty breathing, feeling like your throat is closing
• Swelling of your face, lips, tongue, or throat
• A widespread itchy rash (hives/raised bumps) all over your body
• Feeling faint, dizzy, or your heart racing very fast
• Feeling a sudden intense fear or panic, seeing or hearing strange things (rare — tell the staff, they will help you)

• Sudden jerking movements of your arms, legs, or face
• A seizure (fit/convulsion)
• Confusion or unusual drowsiness
• Pain, swelling, or redness at the IV drip site"

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• RF prophylaxis: ”This injection is needed for many years — sometimes for life. Do NOT stop without your doctor’s permission, even if you feel perfectly well. Stopping puts your heart at serious risk.“
• Syphilis: ”Most cases need only one injection (or 3 weekly injections for some types). After treatment, you need blood tests at 6 months and 12 months to make sure the infection has been cured.“
• Serious infections (IV): ”The IV medicine is usually given for 1–6 weeks depending on the type of infection. The full course must be completed even if you feel better.“

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• RF prophylaxis: ”Come for your injection every 3 weeks. Have a heart check-up (echo test) once a year.“
• Syphilis: ”Come for a blood test (RPR/VDRL) at 3 months, 6 months, and 12 months after treatment to confirm cure. If you are pregnant, extra tests may be needed.“

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• Mark the injection dates on a calendar visible at home. Set a phone reminder.
• ⚠️ Never skip or delay an injection — each missed injection puts your child’s heart at risk of permanent damage.
• After each injection, stay at the clinic for 30 minutes before going home. Watch for any unusual reaction (difficulty breathing, rash, swelling, extreme distress).
• Apply EMLA cream (numbing cream) to the injection site 60 minutes before coming to the clinic — this significantly reduces pain for the child.
• Reassure the child — the injection hurts briefly but protects the heart for life.
• Keep the injection card safe — bring it to every appointment."

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BRANDS AVAILABLE IN INDIA

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• Maintain awareness of current local supply status
• Register patients with the state drug supply system for priority allocation
• Have a contingency plan (oral penicillin V, erythromycin) ready for periods of unavailability
• Report supply shortages to the state drug controller and CDSCO

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PRICE RANGE (INR)

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CLINICAL PEARLS

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VERSION

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REFERENCES

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1. CDSCO Product Insert — Penidure LA (benzathine benzylpenicillin) injection 6 lakh and 12 lakh units, Wyeth Ltd / Pfizer India (and subsequent licensed manufacturers). Approved indications, contraindications, dosing, and adverse effects. Most recently reviewed insert.
2. CDSCO Product Insert — Crystalline Penicillin G Sodium Injection IP, Hindustan Antibiotics Limited (HAL) and generic manufacturers. Approved indications, dosing, and adverse effects.
3. Indian Pharmacopoeia 2022 (IP 2022), Indian Pharmacopoeia Commission, Ghaziabad. 8th Edition. Monographs on Benzylpenicillin Sodium, Benzathine Benzylpenicillin, and Procaine Benzylpenicillin — specifications and official standards.
4. National List of Essential Medicines (NLEM) India 2022, Ministry of Health & Family Welfare, Government of India. Section 6.2 — Beta-lactam medicines: Benzylpenicillin (injection), Benzathine benzylpenicillin (injection), Procaine benzylpenicillin (injection) are listed.
5. Goodman & Gilman’s The Pharmacological Basis of Therapeutics, 14th Edition (2023). Chapter 58: Penicillins, Cephalosporins, and Other Beta-Lactam Antibiotics. Pharmacology of benzylpenicillin — mechanism of action, spectrum, pharmacokinetics (including time-dependent killing, CSF penetration, renal excretion via OAT transporters), adverse effects, and drug interactions.
6. Harrison’s Principles of Internal Medicine, 21st Edition (2022). Chapters on: Infective Endocarditis; Meningitis and Encephalitis; Syphilis; Rheumatic Fever; Gas Gangrene and Clostridial Infections; Diphtheria; Tetanus; Leptospirosis. Treatment references for benzylpenicillin in each condition.
7. API Textbook of Medicine, 11th Edition (2019), Association of Physicians of India. Chapters on: Rheumatic Fever and RHD (RF prophylaxis — 3-weekly benzathine penicillin recommendation); Syphilis; Bacterial Meningitis; Infective Endocarditis; Tetanus (metronidazole preferred over penicillin); Diphtheria; Leptospirosis.
8. ICMR Guidelines on RF/RHD Prevention (2008). Recommends benzathine penicillin 1.2 MU IM every 3 weeks for secondary prophylaxis. Duration guidelines based on severity of carditis.
9. NVHCP (National Programme for Prevention and Control of RHD) — Operational Guidelines, Ministry of Health & Family Welfare, Government of India. RF/RHD registry, prophylaxis delivery protocols, and contingency guidance during benzathine penicillin supply shortages.
10. NACO (National AIDS Control Organisation) — STI/RTI Treatment Guidelines (Current Edition). Syphilis treatment protocols for all stages; congenital syphilis prevention; GBS prophylaxis guidance (where adopted).
11. WHO Guidelines for the Treatment of Treponema pallidum (Syphilis), 2016. Benzathine penicillin dosing for early syphilis, late syphilis, neurosyphilis, and congenital syphilis.
12. NNF (National Neonatology Forum) Protocol for Management of Neonatal Sepsis. Benzylpenicillin + gentamicin as empirical first-line regimen; gestational age-based dosing.
13. IAP-NNF Evidence-Based Clinical Practice Guidelines on Neonatal Sepsis (2021). Antibiotic dosing in neonates; benzylpenicillin gestational age-adjusted dosing tables.
14. IAP Textbook of Pediatrics, 6th Edition (2021), Indian Academy of Pediatrics. Sections on: neonatal sepsis, meningitis, RF/RHD, GAS pharyngitis, congenital syphilis, diphtheria. Dosing and management recommendations.
15. IAP Guidelines on Acute Pharyngitis and RF Prevention (2017). Benzathine penicillin single dose for GAS pharyngitis as RF prevention strategy.
16. WHO Pocket Book of Hospital Care for Children (Indian Adaptation), MoHFW. Antimicrobial dosing including penicillin formulations for paediatric infections.
17. F-IMNCI (Facility-Based Integrated Management of Neonatal and Childhood Illness), MoHFW. Procaine penicillin / FPP dosing for severe pneumonia in children at PHC/CHC level.
18. FOGSI Guidelines on Intrapartum GBS Prophylaxis — where adopted. Crystalline penicillin IV dosing for intrapartum prophylaxis.
19. NCDC (National Centre for Disease Control) Modules — Diphtheria treatment protocol; Meningococcal disease outbreak response; Anthrax treatment guidelines.
20. AHA/ESC Guidelines on Infective Endocarditis — adapted for Indian practice. Penicillin dosing for streptococcal endocarditis; gentamicin synergy protocols.
21. ICMR Leptospirosis Treatment Guidelines. Crystalline penicillin IV for severe leptospirosis; Kerala State Leptospirosis Protocol.
22. NPPA (National Pharmaceutical Pricing Authority) — Drug Prices Control Order (DPCO) schedule and ceiling price notifications. Benzylpenicillin (all salt forms) is NPPA price-controlled under NLEM scheduling.
23. PMBJP (Pradhan Mantri Bhartiya Janaushadhi Pariyojana) — Product catalogue reviewed. Benzylpenicillin sodium injection is listed.
24. CDSCO website (https://cdsco.gov.in) — Reviewed for banned FDC notifications, NSQ alerts, and product recall notices relevant to penicillin-containing formulations.
25. PvPI (Pharmacovigilance Programme of India) — ADR reporting methodology referenced. IPC National Coordinating Centre, Indian Pharmacopoeia Commission.
26. Cochrane Database of Systematic Reviews — Reviews on: (a) Secondary prophylaxis for RF (benzathine penicillin vs oral penicillin); (b) Treatment of syphilis in pregnancy; © Antibiotic treatment of tetanus (metronidazole vs penicillin). Referenced for evidence grading.
27. Indian Heart Journal — Position statements on RF prophylaxis, supply shortage contingency, and 3-weekly vs 4-weekly benzathine penicillin.
28. Matok I et al. (for syphilis pregnancy safety context) and multiple syphilis treatment cohort studies — Referenced indirectly for syphilis treatment evidence base.

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