General Medicine

Notes

Drugs Prescribing and Therapeutics

Oxygen (15 L/min)

Full size D cylinder : 340L ~ 22 mins
Full size CD cylinder : 460L ~ 30 mins
Full size E cylinder : 680 L ~ 45 mins

Drugs for Medical Emergencies

Adrenaline - 0.5 ml 1:1000 IM
Aspirin - 300 mg tab (75 g for prophylaxis)
Glucagon - 1 mg IM
GTN spray - 2 puffs 400 mcg / metered dose sublingually
Midazolam - 10 mg buccal
Oral glucose - 10 - 20 g fast acting glucose
Oxygen - 100% 15 L/min
Salbutamol - 4 puffs 100 mcg / actuation through large-volume spacer

Mild allergy - Cetirizine 10 mg tab / Chlorphenamine 4 mg tab / Loratidine 10 mg tab

Anxiety - Diazepam 5 mg tab 2 hr before procedure

Prescriptions

Cellulitis / spreading infection / systemic involvement

C. Amoxicillin 500 mg TDS 5 days
T. Phenoxymethylpenicillin 500 mg QID 5 days
T. Metronidazole 200 mg TDS 5 days (✖ warfarin, alcohol → disulfiram-like action)

2nd-line antibiotic for dental abscess

C. Clindamycin 150 mg QID 5 days (✖ diarrhoea)
T. Co-amoxiclav 250 / 125 mg TDS 5 days (✖ hepatic dysfunction, jaundice)
T. Clarithromycin 250 mg BD 7 days (✖ hepatic, renal impairment, pregnant, nursing, warfarin, statins)

NUG / NUP / Pericoronitis

C. Amoxicillin 500 mg TDS 3 days
T. Metronidazole 200 mg TDS 3 days

Sinusitis (self-limiting 2 1/2 weeks)

Ephedrine nasal drops 0.5% 10 ml 1 drop TDS max 7 days (✖ HPT, < 12 y/o)
C. Amoxicillin 500 mg TDS 5 days
C. Doxycycline 100 mg 2 cap (1st day), 1 cap OD 7 days (✖ hepatic impairment, pregnant, nursing, < 12 y/o, warfarin)

Pseudomembranous candidosis / erythematous candidosis / denture stomatitis

C. Fluconazole 50 mg OD 7 days (✖ warfarin, statins)
Miconazole oromucosal gel 20 mg / g 80g, pea-sized after food QID 7 days after lesions have healed (✖ warfarin, statins)
Nystatin oral suspension 100,000 units / ml, 30 ml, 1 ml after food QID 7 days - continue for 48 hrs after lesions have healed

Angular cheilitis

Miconazole cream 2% 20 g , apply to angle of mouth BD, continue use for 10 days after lesions have healed
Sodium fusidate ointment 2% 15 g, apply to angle of mouth BD, max 10 days
Miconazole 2% & hydrocortisone 1% cream or ointment, apply to angle of mouth BD, max 7 days (✖ warfarin, statins)

HSV infection

CHX mouthwash 0.2% 300 ml, 10 ml 1 min BD
H2O2 mouthwash 6% 300 ml, 15 ml diluted in half a tumbler warm water 2 mins TDS
T. Aciclovir 200 mg 5 times / day 5 days

VZ infection (within 72 hrs of rash - reduce severity of post-herpetic neuralgia)

T. Aciclovir 800 mg 5 times / day 7 days

Mild to moderate odontogenic pain

T. PCM 1000 mg QID 5 days
T. Ibuprofen 400 mg QID 5 days (✖ pregnant, peptic ulcer, hypersensitivity)
T. Aspirin 600 mg QID 5 days (✖ Xn/MOS, hypersensitivity, nursing, peptic ulcer, < 16 y/o)

Moderate inflammatory / post-op pain

T. Diclofenac sodium 50 mg TDS 5 days (✖ IHD, cerebrovascular disease, peripheral arterial disease, heart failure, hypersensitivity, aspirin, peptic ulcer)

Peptic ulcer (PCM alone not sufficient)

C. Lansoprazole 15 mg OD 5 days
C. Omeprazole 20 mg OD 5 days

Trigeminal neuralgia

T. Carbamazepine 100 mg BD 10 days

TMJ dysfunction (+ ibuprofen)

T. Diazepam 2 mg TDS 5 days

Mucosal Ulceration (e.g. RAS)

① Antimicrobial m/w

CHX
H2O2
T. Doxycycline dispersible 100 mg dissolved in water, 2 mins, QID 3 days (✖ pregnant, nursing, < 12 y/o)

② Local analgesics

0.15% Benzydamine m/w 15 ml every 1 1/2 hr max 7 days
0.15% Benzydamine oromucosal spray 4 sprays every 1 1/2 hr
5% Lidocaine ointment rub sparingly and gently on affected areas
10% Lidocaine spray apply as necessary with cotton bud

③ Topical corticosteroids

Beclometasone diproprionate inhaler 50 mg, 1- 2 puffs BD
T. Hydrocortisone oromucosal 2.5 mg dissolved next to lesion BD

👉 Suspected adverse drug reactions → reported to Medicines & Healthcare Products Regulatory Agency (MHRA)

Therapeutic index = safety of drug

Latency = from administration of drug → onset of action

Idiosyncrasy = abnormal physical reaction → food / drug

Drug best absorbed : ↓ molecular weight, unionized, lipid soluble

Mechanism of Action

Gentamicin : blocks protein synthesis 30s ribosomal subunit
Erythromycin : blocks protein synthesis 50s ribosomal subunit
Rifampicin : blocks mRNA synthesis
Vancomycin : blocks peptidoglycan synthesis
Penicillin : blocks cell wall synthesis
Sulphonamides : interfere with folinic acid production
Metronidazole : inhibits nucleic acid synthesis

Management of Patient on Bisphosphonate

👉 reduce bone resorption : hindering formation, recruitment and function of osteoclasts

👉 e.g. alendronic acid, zoledronic acid, etidronate disodium etc.

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) = necrotic bone in Mx / Mb that has persisted for > 8 weeks and no history of radiation therapy to jaw

• delayed healing following dental extraction / oral surgery
• pain
• soft tissue infection
• swelling
• numbness
• paraesthesia
• exposed bone

👉 extremely rare condition

Guidance

① Avoid extraction / oral surgery if there is an alternative treatment option

② If any extraction / oral surgery is necessary, assess patient risk

low : before / taking bisphosphonate for prevention / management of osteoporosis

high : previous diagnosis of BRONJ, malignant condition, non-malignant systemic condition affecting bone (e.g. Paget's disease), rare medical condition (e.g. osteogenesis imperfecta), concurrent use of systemic corticosteroids / immunosuppressants, coagulopathy, chemotherapy, radiotherapy

Management of Patient on Anticoagulants

Antiplatelets - aspirin, dipyridamole, clopidogrel : interfere with platelet aggregation

Oral anticoagulants - warfarin, acenocoumarol, phenidione : inhibit vitamin K-dependent modification of prothrombin and other coagulation factors

Novel oral anticoagulants - dabigratran : direct inhibitor of coagulation factor thrombin, apixaban, rivaroxaban : inhibit Factor Xa (❌ require monitoring)

Injectable anticoagulants - heparin, dalteparin, enoxaparin, tinzaparin : bind to antithrombin III

Cranial Nerves

1, 2, 8 → sensory (nose, eyes, ears)
5, 7, 9, 10 → mixed

others → motor

Ⅰ Olfactory - cribriform plate

Ⅱ Optic - optic canal

Ⅲ Oculomotor - superior orbital fissure (SOF)

Ⅳ Trochlear - SOF

Ⅴ Trigeminal

• opthalmic - SOF
• maxillary - foramen rotundum
• mandibular - foramen ovale

Ⅵ Abducens - SOF

Ⅶ Facial - enter internal acoustic meatus (IAM), leave stylomastoid foramen (SMF) - salivation SM, SL gland

Ⅷ Vestibulocochlear - IAM

Ⅸ Glossopharyngeal - jugular foramen - salivation P gland, gag reflex

Ⅹ Vagus - jugular foramen - uvula pointing away, hoarseness, gag reflex

Ⅺ Accessory - jugular foramen - SCM, trapezius

Ⅻ Hypoglossal - hypoglossal foramen - pointing towards