Medicines 9 - Infections Flashcards
What antibiotics can interact with alcohol
completely avoid drinking alcohol when taking:
metronidazole - an antibiotic sometimes used to clear dental, or vaginal, infections, or to clear infected leg ulcers, or pressure sores
tinidazole - an antibiotic sometimes used to treat many of the same infections as metronidazole, as well as to help clear bacteria called Helicobacter pylori (H pylori) from the gut.
co-trimoxazole - drinking alcohol while taking co-trimoxazole can occasionally cause a similar reaction to that of metronidazole or tinidazole, although this is very rare. Drinking alcohol in moderation does not normally cause a problem
linezolid - linezolid can interact with un-distilled (fermented) alcoholic drinks, such as wine, beer, sherry and lager
doxycycline - this is known to interact with alcohol and in people with a history of chronic alcohol consumption the effectiveness of doxyclycline may be reduced. It should not be taken by people with liver problems
erythromycin - there is some evidence or a minor interaction with alcohol that may slightly reduce or delay the effect of erythromycin
What is flucloxacillin used to treat?
FLUCLOXACILLIN - Penicillin-resistant Staphylococcal infections except MRSA
e.g. skin infections: impetigo, cellulitis.
π Why MRSA is mentioned:
Flucloxacillin is specifically used for staph infections, and it works against most strains β except MRSA.
Since MRSA is resistant to all beta-lactams, including flucloxacillin, this exception is crucial to highlight.
What is a key side effects to note with flucloxacillin
CHOLESTATIC JAUNDICE AND HEPATITIS
Up to two months after treatment.
Increasing age and >14 days treatment increases risk.
What are the different spectrums of penicillins?
NARROW-SPECTRUM (beta-lactamase sensitive)
- BENZYLPENICILLIN βPEN Gβ
* PHENOXYMETHYLPENICILLIN βPEN Vβ
BROAD-SPECTRUM (inactivated by beta-lactamases)
* AMPICILLIN
- AMOXICILLIN
PENICILLINASE-RESISTANT
* FLUCLOXACILLIN - Penicillin-resistant Staphylococcal infections except MRSA
What are the different indications for metronidazole?
- Treatment of anaerobic bacteria - e.g. dental infections, antibiotic-associated
- colitis, h.pylori, rosacea, bacterial vaginosis.
- Antibiotic-associated colitis caused by c.difficile β gram positive anaerobe
- Oral infections or aspiration pneumonia = gram negative anaerobes in mouth
- Surgical and gynaecological infections β gram negative anaerobes from colon
- Protozoal infections
What are the key contraindications of metronidazole and SEs?
- Metabolised by CYP450 enzymes
- Severe liver disease β REDUCE total daily dose to 1/3 and give once daily
- Avoid alcohol β disulfiram-like effect = flushing, headache, nausea and vomiting (because metronidazole inhibits the enzyme that breaks down a compound of alcohol) = do not drink during or for 48 hours after treatment.
- topical use: avoid exposure to strong sunlight or UV light
- avoid large doses in pregnancy and breastfeeding
How often is amoxicillin given dosing wise in a H.Pylori infection?
TWICE DAILY instead of common three
1 g twice daily for 7 days for first- and second-line eradication therapy; 10 days for third-line eradication therapy.
What is the usual dosing schedule of clarithromycin
TWICE DAILY!!
Whats the first line treatment for athletes foot?
Terbinafine 1% cream
Clotrimazole 1% cream (2% not licensed)
Miconazole 2% cream
This antibiotic is bactericidal and acts by interfering with bacterial cell wall synthesis. It diffuses well into body tissues and fluids, but penetration into the cerebrospinal fluid is poor except when the meninges are inflamed. It is excreted in the urine in therapeutic concentrations
This describes which antibiotic
NARROW-SPECTRUM (beta-lactamase sensitive) penicillins
- BENZYLPENICILLIN βPEN Gβ
- PHENOXYMETHYLPENICILLIN βPEN Vβ
What is a key caution with mefloquine
Neuropsychiatric reactions
Mefloquine is associated with potentially serious neuropsychiatric reactions. Abnormal dreams, insomnia, anxiety, and depression occur commonly. Psychosis, suicidal ideation, and suicide have also been reported. Psychiatric symptoms such as insomnia, nightmares, acute anxiety, depression, restlessness, or confusion should be regarded as potentially prodromal for a more serious event. Adverse reactions may occur and persist up to several months after discontinuation because mefloquine has a long half-life. For a prescribing checklist, and further information on side-effects, particularly neuropsychiatric side-effects, which may be associated with the use of mefloquine for malaria prophylaxis, see the Guide for Healthcare Professionals provided by the manufacturer.
whats the MHRA alerts regarding chloroquine and hydroxychloroquine?
MHRA/CHM advice: Hydroxychloroquine, chloroquine: increased risk of cardiovascular events when used with macrolide antibiotics; reminder of psychiatric reactions (February 2022)
An observational study has shown that co-administration of azithromycin with hydroxychloroquine in patients with rheumatoid arthritis was associated with an increased risk of cardiovascular events (including angina or chest pain and heart failure) and mortality. Healthcare professionals are reminded to consider the benefits and risks of co-prescribing systemic azithromycin, or other systemic macrolides, with hydroxychloroquine. If such use cannot be avoided, caution is recommended in patients with risk factors for cardiac events and they should be advised to seek urgent medical attention if any signs or symptoms develop.
A European safety review has reported that psychiatric reactions associated with hydroxychloroquine (including rare cases of suicidal behaviour) typically occurred within the first month of treatment; events have been reported in patients with no history of psychiatric disorders. Healthcare professionals are reminded to be vigilant for psychiatric reactions, and counsel patients and carers to seek medical advice if any new or worsening mental health symptoms develop.
what is oseltamivir used to treat?
Reduces replication of influenza A and B viruses by inhibiting viral neuraminidase.
which doac does not have a reversible agent?
EDOXABAN
dabigatran etexilate, apixaban, and rivaroxaban do have one.
Idarucizumab is licensed for the rapid reversal of dabigatran etexilate in life-threatening or uncontrolled bleeding, or for emergency surgery or urgent procedures.
Andexanet alfa is licensed for the reversal of apixaban or rivaroxaban in life-threatening or uncontrolled bleeding.
What are the main indications of Minocycline?
Susceptible infections (e.g. chlamydia, rickettsia and mycoplasma)
Acne
What key counselling points are of note with minocycline?
To reduce the risk of oesophageal irritation and ulceration, the capsules should be swallowed whole with plenty of fluid, while sitting or standing. Unlike other tetraacyclines, absorption of minocycline is not significantly impaired by food or moderate amounts of milk.
What is the treatment and dose of acute lower UTIs in men
Trimethoprim 200 mg twice daily for 7 days.
OR
Nitrofurantoin 100 mg modified-release twice daily (or if unavailable 50 mg four times daily) for 7 days.
What are the side effects of Cephalasporins?
Side effects
* GI upset: nausea, diarrhoea
* Antibiotic associated colitis β kill normal gut flora allowing c.difficile to grow β more common in 2nd and 3rd generations
* Hypersensitivity due to penicillins: rashes
* CNS toxicity: seizures
What counselling is required with cephalasporins?
- Before you take cefalexin, make sure your doctor knows if you have ever had an allergic reaction to an antibiotic.
- Space out your doses evenly over the day and complete the full course.
- The most common side-effect is diarrhoea, which is usually mild and soon passes. If it becomes severe or lasts for more than 24 hours, you should speak with your doctor.
- If you are taking the contraceptive βpillβ at the same time as an antibiotic, the effectiveness of the βpillβ can be reduced if you have a bout of being sick (vomiting) or diarrhoea which lasts for more than 24 hours. If this should happen, ask your doctor or pharmacist for advice about what additional contraceptive precautions to use.
What are the main uses of Amoniglycosides like Gentamycin
- Severe infections especially caused by gram negative aerobes incl. pseudomonas aeruginosa
- Severe sepsis β incl. where source is not identified
- Pyelonephritis and complicated UTI
- Biliary and other intra-abdominal sepsis
- Endocarditis
Given via parenteral injection; not absorbed by gut.
What are the different aminoglycosides and their main uses?
GENTAMICIN (Choice; active against pseudomonas aeruginosa)
TOBRAMYCIN (via inhaler for pseudomonal infection in cystic fibrosis)
STREPTOMYCIN (active against mycobacteria reserved for T B)
NEOMYCIN (Parenterally toxic. Use in bowel sterilization)
AMIKACIN (Gentamicin-resistant Gram-negative bacilli)
What are the main side effects with aminoglycosides?
Dose-related; do not exceed 7 days.
Commonly occur in elderly and in renal failure; renally cleared.
* Nephrotoxicity β Aminoglycosides excreted by kidney. reduced urine output, rising serum creatinine and urea β may be reversible. Assess renal function before treatment and correct any dehydration.
* Ototoxicity β not usually noticed until after resolution of infection β hearing loss, tinnitus, vertigo = may be irreversible -
* Hypokalaemia
OTHER SIDE EFFECTS:
* PERIPHERAL NEUROPATHY
* IMPAIRED NEUROMUSCULAR TRANSMISSION
Contra-indicated in myasthenia gravis.
* ELECTROLYTES:
Hypo K, Ca and Mg.
MHRA/CHM advice (November 2017): potential for histamine-
related adverse drug reactions with some batches.
* Some batches may contain histamine residual from manufacturing process
* Monitor patients for signs of histamine-related reactions.
* Take particular caution in concomitant drugs known to cause histamine release, in children and severe renal impairment.
What do you do regarding peak and trough doses with Gentamycin?
Monitor after 3 or 4 doses and after a dose change
but in renal impairment requires more frequent and earlier monitoring.
WHAT TO DO?
* Post-dose βpeakβ level after 1 hour is too high = Reduce dose
5-10mg/mL (3-5mg/mL for endocarditis)- Gentamicin
* Pre-dose βtroughβ level before next dose is too high = Increase interval
<2mg/mL (<1 mg/mL for endocarditis) - Gentamicin
* In renal impairment = increase interval
* In severe renal impairment (<30mI/min) = reduce dose
WHat are the key counselling points with Metronidazole ?
- Swallow metronidazole tablets with plenty of water. Take them with a meal or a snack.
- Do not drink alcohol while you are on metronidazole, or for 48 hours afterwards.
- Space doses evenly throughout the day, and keep taking the tablets/medicine until the course is finished.
- urine may look a darker (dark or reddish-brown urine) colour than normal β this is nothing to worry about.
What are the key side effects with trimethoprim?
- GI upset: nausea, vomiting, sore mouth
- Skin rash
- Severe hypersensitivity: anaphylaxis, drug fever, erythema multiforme = more common with sulphonamides = limits their use
- Trimethoprim can impair haematopoiesis = haematological disorders: megaloblastic anaemia, leukopenia, thrombocytopenia - BLOOD DYSCRASIAS: with long-term use. Patient counseling: report fever, sore throat, rash, mouth ulcers, purpura, bruising, bleeding.
- Hyperkalaemia
- Increases plasma creatinine concentrations
- Photosensitivity
What is the effect when trimethoprim is given with the following drugs:
* ACE inhibitors, ARBs, spironolactone
* Amiodarone
* Azathioprine
* Ciclosporin, Tacrolimus
* Coumarins
* Digoxin
* Phenytoin
* Methotrexate
* Repaglinide
- ACE inhibitors, ARBs, spironolactone β increased risk of hyperkalaemia
- Amiodarone β increased risk of ventricular arrhythmias when trimethoprim (as co-trimoxazole) given with amiodaroneβmanufacturer of amiodarone advises avoid with co-trimoxazole
- Azathioprine β increased risk of haematological toxicity
- Ciclosporin, Tacrolimus β increased risk of nephrotoxicity when trimethoprim given with ciclosporin, also plasma concentration of ciclosporin reduced by intravenous trimethoprim
- Coumarins β enhances anticoagulant effect by killing normal gut flora that synthesis vitamin K
- Digoxin β increased concentrations of digoxin
- Phenytoin β increases plasma concentration of Phenytoin (also increased antifolate effect)
- Methotrexate β increased risk of severe bone marrow depression (fatalities reported) and other haematological toxicities
- Repaglinide β enhances hypoglycaemic effect β avoid
What are the main indications for chloramphenicol?
- Superficial eye infections: conjunctivitis
- Bacterial infection in otitis externa
- Infections caused by haemophilus influenza and typhoid fever
What are the key side effects and cautions of chloramphenicol?
(think of formulation)
Side effects
* Stinging in the eye
* Blood disorders including aplastic anaemia- with IV
* Depression β with IV
* Neurological abnormalities: optic neuritis
* Grey baby syndrome when used IV in neonates -AVOID
Cautions and contraindications; conditions
* Avoid prolonged use in the ear
* Reduce dose or avoid in hepatic impairment
* Avoid in severe renal impairment
* Avoid repeated courses and prolonged treatment
* Avoid in neonates β GREY BABY SYNDROME
What are some key side effects of rifampicin?
- GI upset: nausea, vomiting, diarrhoea
- May give rise to hepatitis- jaundice
- Skin rashes and haematological abnormalities
- Orange- red discolouration of tears β staining of contact lenses, urine and other bodily fluids
- Eosinophilia, anaemia
- Influenza like symptoms: fever, chills, bone pain
What are some key counselling points with rifampicin?
- Rifampicin may discolour soft contact lenses, urine and other bodily fluids β donβt worry
- Look out for signs of liver disorder: persistent malaise, nausea, vomiting, jaundice
- Take your doses about an hour before a meal, or wait until two hours afterwards.
- Use effective contraception
What type of drug is vancomycin
what are the main indications of Vancomycin
Glycopeptide antibiotic
Gram-positive infection: endocarditis where infection is severe and or penicillins cannot be used due to resistance (MRSA)
Antibiotic-associated colitis caused by c. difficile infection second line to metronidazole
What are the side effects to note with vancomycin?
πΉ Thrombophlebitis β Pain & inflammation at infusion site
β οΈ Red Man Syndrome β Erythema, hypotension, bronchospasm (if infused too fast)
π©Ί Nephrotoxicity β Risk of renal failure & interstitial nephritis
π Ototoxicity β Tinnitus & hearing loss
π©Έ Blood Disorders β Neutropenia, thrombocytopenia (may occur after 1 week)
What are the cautions/contraindications with vancomycin?
β οΈ Vancomycin β Cautions & Contraindications
πΉ Monitor plasma drug levels carefully
πΉ Renal impairment β Requires dose reduction
πΉ Elderly β Dose reduction due to higher risk of hearing impairment
π« Avoid in history of deafness
What key interactions is there with Vancomycin?
β οΈ Vancomycin β Important Drug Interactions
πΉ Aminoglycosides β β Risk of nephrotoxicity & ototoxicity
πΉ Amphotericin β β Risk of nephrotoxicity
πΉ General Anaesthetics β May cause hypersensitivity-like reactions
πΉ Ciclosporin & Tacrolimus β β Risk of nephrotoxicity
πΉ Loop Diuretics β β Risk of ototoxicity
What are the monitoring requirements for Vancomycin?
πΉ Renal Impairment β Regular plasma-vancomycin, renal, & auditory function monitoring
πΉ Plasma Levels β Measure after 3β4 doses (earlier if renal impairment or dose change)
πΉ Trough Levels:
10β15 mg/L (standard infections)
15β20 mg/L (endocarditis, MRSA, complicated S. aureus infections)
πΉ Consider Loading Dose β Follow local guidelines
πΉ Routine Tests for All Patients:
Blood counts, urinalysis, renal function tests
Elderly β Monitor hearing function
What is a key SE to be aware of with clindamycin?
- ANTIBIOTIC- ASSOCIATED COLITIS
Most frequently with Clindamycin β can be fatal
Most common in middle-aged, elderly women, especially after operations
Patient Counseling: if diarrhoea develops: STOP! and see GP.
What antibacterial therapy can be used in COPD Prophylaxis
Treatment with azithromycin 500 mg three times per week, should be considered for a minimum of 6β12 months to assess evidence of efficacy in reducing exacerbations. (NICE)
What are the main uses of ketoconazole and nystatin?
πΉ Local fungal infections β Oropharynx, vagina, skin (nystatin, clotrimazole topically; fluconazole orally)
πΉ Systemic fungal infections β Invasive, disseminated infections (fluconazole)
πΉ Nystatin β First-line for oral thrush
β How do ketoconazole and nystatin work?
π¦ Fungal cell membranes contain ergosterol, absent in human cells
πΉ Polyene antifungals (Nystatin) β Bind to ergosterol, forming pores β leaks intracellular ions β fungicidal
πΉ Azoles (Clotrimazole, Fluconazole, Ketoconazole) β Inhibit ergosterol synthesis via CYP450-dependent 14Ξ±-lanosterol demethylation
What are the key side effects of ketoconazole, nystatin, and fluconazole?
𧴠Topical Nystatin & Clotrimazole:
Local irritation, itching
π« Clotrimazole creams may damage condoms
π Fluconazole:
Common: GI upset, headache, rash
Severe: Hepatitis, QT prolongation (arrhythmias), anaphylaxis
π« Ketoconazole:
Oral use not recommended β Severe hepatotoxicity
Topical: Erythema, itching, irritation
What cautions and contraindications should be considered for these antifungals?
𧴠Nystatin & Clotrimazole:
π« Avoid contact with eyes & mucous membranes
π Fluconazole:
β οΈ Liver disease β Risk of hepatotoxicity
β οΈ Renal impairment β Reduce dose
π« Pregnancy β Risk of fetal malformation
β οΈ QT prolongation risk
π« Ketoconazole:
Avoid oral use in pregnancy & breastfeeding
What are the key drug interactions with fluconazole?
πΉ β Plasma Levels of:
Aminophylline, Theophylline
Amitriptyline, Diazepam (β sedation)
Atorvastatin, Simvastatin (β myopathy risk)
Carbamazepine, Phenytoin
Ciclosporin, Tacrolimus (β immunosuppressant levels)
Fentanyl, Quetiapine
πΉ β Effectiveness of:
Clopidogrel (β antiplatelet effect)
Rifampicin (β fluconazole metabolism)
πΉ Avoid with:
Erythromycin (QT prolongation risk)
πΉ β Anticoagulant Effect:
Warfarin (Coumarins)
π What monitoring is required for antifungal use?
πΉ Ketoconazole (Oral Use):
ECG β Before & 1 week after initiation
Adrenal Function β Within 1 week, then every 3β6 months
Liver Function β Before, then weekly for 1 month, monthly for 6 months
πΉ Fluconazole:
Monitor LFTs in high doses or long-term use
π What patient counselling is needed for antifungals?
𧴠Nystatin:
𧴠Clotrimazole:
𧴠Ketoconazole:
π Fluconazole:
𧴠Nystatin:
Use 4Γ daily after food
Hold in mouth before swallowing for better contact with lesions
𧴠Clotrimazole:
If no improvement in 7 days, see a doctor
Limit to 2 courses in 6 months without medical advice
Pessary & intravaginal cream β Insert at bedtime
π« Can damage condoms β Use alternative contraception
𧴠Ketoconazole:
Apply 1β2Γ daily (twice for athleteβs foot)
Continue until infection fully clears
Groin/genital infections may take 6 weeks
π Fluconazole:
Vaginal thrush β Single 150 mg dose
Can be taken with or without food
Longer courses for systemic infections
π What are the main uses of Terbinafine?
β
Tinea infections β Athleteβs foot (Tinea pedis), Ringworm (Tinea corporis), Jock itch (Tinea cruris)
β
Dermatophyte nail infections
β
Cutaneous candidiasis
Dosage:
Oral β Once daily
Topical β 1-2Γ daily
βοΈ What is the mechanism of action of Terbinafine?
πΉ Inhibits squalene epoxidase β blocks ergosterol synthesis, an essential fungal cell membrane component
πΉ Leads to fungal cell death (fungicidal action)
β οΈ What are the side effects of Terbinafine?
GI upset: Abdominal discomfort, anorexia, dyspepsia, diarrhoea
Liver toxicity: Jaundice, cholestasis, hepatitis
Severe skin reactions: Stevens-Johnson Syndrome (SJS), Toxic Epidermal Necrolysis (TEN)
β οΈ What are the cautions & contraindications for Terbinafine?
π« Discontinue if:
Liver toxicity (jaundice, cholestasis, hepatitis)
Severe skin rash (SJS, TEN)
β οΈ Caution in:
Hepatic impairment (oral use) β Reduces elimination
Renal impairment β Half the dose
Avoid in breastfeeding
π What are the important drug interactions of Terbinafine?
πΉ Increases Plasma Levels of:
Tricyclic Antidepressants
Fluconazole
πΉ Reduces Plasma Levels of:
Ciclosporin
Rifampicin (reduces terbinafine levels)
πΉ Other Effects:
Cimetidine β terbinafine levels
Oestrogens, Progestogens β Risk of breakthrough bleeding with hormonal contraception
π What patient counselling is needed for Terbinafine?
β
For Oral Use:
Take once daily and complete the full course
β
For Topical Use:
Apply thinly to affected area 1-2Γ daily for 1 week
Wash & dry affected area before applying cream
Wash clothes & bedding frequently to remove fungus
Avoid sharing towels
Wear loose clothing & cotton socks (if treating feet)
Keep feet cool & dry β choose breathable footwear
Avoid scratching to prevent spread
Wash hands after touching the infected area
β
Additional Advice:
Terbinafine 1% cream can be sold OTC to people >16 years
π What are the main uses of Mebendazole?
β
Threadworm infections
β
Hookworm infections
β
Roundworm infections
βοΈ What is the mechanism of action of Mebendazole?
πΉ Binds to Ξ²-tubulin in the worm cells
πΉ Prevents polymerization of tubulin
πΉ Inhibits glucose uptake, organelle production, and ATP production
πΉ Parasite dies due to lack of energy
β οΈ What are the side effects of Mebendazole?
GI issues: Abdominal pain, diarrhoea, flatulence
Other effects: Dizziness, rash
Severe reactions: Stevens-Johnson syndrome, hepatitis
β οΈ What are the cautions and contraindications for Mebendazole?
π« Avoid in:
Pregnancy β give lifestyle measures instead
Children under 2 years
β οΈ High doses:
Close monitoring with regular blood counts
What are the drug interactions with Mebendazole?
πΉ Cimetidine β May inhibit Mebendazole metabolism, increasing plasma concentratio
π What patient counselling is needed for Mebendazole?
β Mebendazole tablets can be sold OTC for the treatment of enterobiasis in adults and children over 2 years.
β Treat everyone in the family on the same day to prevent the spread of infection.
πΉ Wash hands and scrub nails after using the toilet and before eating meals.
πΉ Mebendazole doesnβt kill eggs, so good hygiene is essential to prevent re-infestation.
π What are the main uses of Aciclovir?
β
Herpes simplex infection: Usual treatment for 5 days
β
Varicella zoster virus (shingles): Usual treatment for 7 days
β οΈ What are the side effects of Aciclovir?
Eye use: Local inflammation and irritation
Systemic use:
Abdominal pain, diarrhoea, fatigue
Headache, nausea
Photosensitivity, pruritus, rash
β οΈ What are the cautions and contraindications for Aciclovir?
π« Renal impairment β reduce frequency and dose
β οΈ Caution in elderly with oral use due to risk of neurological reactions
β οΈ Avoid contact with eyes for the cream
β οΈ Parenteral dose should be calculated based on ideal weight for height in obese patients
π What drugs interact with Aciclovir?
πΉ Aminophylline, theophylline β increases plasma concentration
πΉ Ciclosporin, tacrolimus β increased risk of nephrotoxicity
π What patient counselling is needed for Aciclovir?
Drink plenty of water to avoid dehydration
Photosensitivity: Avoid strong sunlight and sunbeds; use a high SPF sunscreen
Avoid sexual contact in genital herpes, as the virus can still be passed on
What are the main bacteria that cause impetigo?
Staphylococcus aureus or Streptococcus pyogenes.
