Co-trimoxazole
CLASS
- 2 antibiotics (sulfamethoxazole and trimethoprim)
MECHANISM OF ACTION
- sulfamethoxazole -> inhibits bacterial synthesis of dihydrofolic acid
- trimethoprim -> blocks production of tetrahydrofolic acid
-> blocks two consecutive steps in the biosythesis of nucleic acids and proteins essential to bacteria.
PHARMACEUTICS
- PO – each tablet = 80mg trimethoprim and 400mg sulfamethoxazole
- IV – 5mL contains 80mg trimethoprim and 400mg sulfamethoxazole (referred to as 480mg, requires appropriate dilution in to a large volume of fluid)
DOSE
- IV: 960-1440mg/day in divided doses, for PCP use 120mg/kg in divided doses Q6hrly for 14 days
- PO: for PCP prophylaxis 960-1920mg on alternate days
INDICATIONS
- PCP (infection and prophylaxis)
- Stenotrophomonas and other multi-drug resistant infections (e.g. MRSA skin infections)
- Nocardia
- Toxoplasmosis
- Gram positive cocci
- Gram negative bacilli (Pseudomonas, xanthomonas)
CONTRAINDICATIONS
- hypersensitivity
- blood dyscrasia
- marked renal or hepatic impairment
- megaloblastic bone marrow
ADVERSE EFFECTS
- photosensitivity
- superinfection (pseudomembranous colitis)
- GI upset
- CNS effects
- interactions: diuretics -> thrombocytopaenia, warfarin -> increase INR
- haematological effects
PHARMACOKINETICS
- Absorption
- Distribution
- Metabolism
- Elimination
References and Links
CCC Pharmacology Series
Respiratory: Bosentan, Delivery of B2 Agonists in Intubated Patients, Nitric Oxide, Oxygen, Prostacyclin, Sildenafil
Cardiovascular: Adenosine, Adrenaline (Epinephrine), Amiodarone, Classification of Vasoactive drugs, Clevidipine, Digoxin, Dobutamine, Dopamine, Levosimendan, Levosimendan vs Dobutamine, Milrinone, Noradrenaline, Phenylephrine, Sodium Nitroprusside (SNiP), Sotalol, Vasopressin
Neurological: Dexmedetomidine, Ketamine, Levetiracetam, Lignocaine, Lithium, Midazolam, Physostigmine, Propofol, Sodium Valproate, Sugammadex, Thiopentone
Endocrine: Desmopressin, Glucagon Therapy, Medications and Thyroid Function
Gastrointestinal: Octreotide, Omeprazole, Ranitidine, Sucralfate, Terlipressin
Genitourinary: Furosemide, Mannitol, Spironolactone
Haematological: Activated Protein C, Alteplase, Aprotinin, Aspirin, Clopidogrel, Dipyridamole, DOACs, Factor VIIa, Heparin, LMW Heparin, Protamine, Prothrombinex, Tenecteplase, Tirofiban, Tranexamic Acid (TXA), Warfarin
Antimicrobial: Antimicrobial Dosing and Kill Characteristics, Benzylpenicillin, Ceftriaxone, Ciprofloxacin, Co-trimoxazole / Bactrim, Fluconazole, Gentamicin, Imipenem, Linezolid, Meropenem, Piperacillin-Tazobactam, Rifampicin, Vancomycin
Analgesic: Alfentanil, Celecoxib, COX II Inhibitors, Ketamine, Lignocaine, Morphine, NSAIDs, Opioids, Paracetamol (Acetaminophen), Paracetamol in Critical Illness, Tramadol
Miscellaneous: Activated Charcoal, Adverse Drug Reactions, Alkali Therapies, Drug Absorption in Critical Illness, Drug Infusion Doses, Epidural Complications, Epidural vs Opioids in Rib Fractures, Magnesium, Methylene Blue, Pharmacology and Critical Illness, PK and Obesity, PK and ECMO, Sodium Bicarbonate Use, Statins in Critical Illness, Therapeutic Drug Monitoring, Weights in Pharmacology
Toxicology: Digibind, Flumazenil, Glucagon Therapy, Intralipid, N-Acetylcysteine, Naloxone, Propofol Infusion Syndrome
Critical Care
Compendium
Chris is an Intensivist and ECMO specialist at The Alfred ICU, where he is Deputy Director (Education). He is a Clinical Adjunct Associate Professor at Monash University, the Lead for the Clinician Educator Incubator programme, and a CICM First Part Examiner.
He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives. He was one of the founders of the FOAM movement (Free Open-Access Medical education) has been recognised for his contributions to education with awards from ANZICS, ANZAHPE, and ACEM.
His one great achievement is being the father of three amazing children.
On Bluesky, he is @precordialthump.bsky.social and on the site that Elon has screwed up, he is @precordialthump.
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