Sorry, I'm late !
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For today I'll post two drugs!
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Diazepam = (Dialar, Diazemuls, Rimapam,
Stesolid, Tensium, Valclair, Valium)
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Description
A benzodiazepine sedative and anxiolytic drug with anticonvulsant
properties.
Indications
Used in dental sedation and preoperative anxiolysis (although it has
now been superseded by midazolam when intravenous techniques
are employed: for oral sedation temazepam is the drug of choice).
Also indicated in the emergency treatment of epilepsy in the dental
surgery.
Presentations
(i) 2 mg, 5 mg, and 10 mg tablets.
(ii) Oral solutions of 2 mg/5 mL and 5 mg/5 mL.
(iii) Solution for injection 5 mg/mL.
(iv) 10 mg suppositories.
(v) Solutions for rectal administration 2 mg/mL and 4 mg/mL
Dose
(i) To treat anxiolysis
2 mg–10 mg three times daily.
(ii) As premedication prior to dental treatment
5–10 mg 1–2 hours prior to the appointment.
(iii) For intravenous dental sedation
incremental doses of 2.5 mg/minute until a satisfactory endpoint
(Verrill’s sign which is drooping of the upper eyelid to
cover half of the pupil). Midazolam has now superseded diazepam
as the intravenous benzodiazepine for dental sedation.
(iv) In the emergency treatment of epilepsy (status epilepticus) in
the dental surgery
5 mg over 1 minute increments intravenously repeated if necessary
up to a dose of 20 mg.
Contraindications
Severe respiratory disease.
Severe liver disease.
Porphyria (although should be used in emergency management of
status epilepticus).
Precautions
History of drug abuse.
Severe liver disease.
Severe muscle weakness (myasthenia gravis).
Pregnancy and breastfeeding.
Unwanted effects
Xerostomia.
Respiratory depression.
Hypotension.
Visual disturbances.
Headache.
Occasionally skin rashes (anaphylaxis is unusual).
Thrombophlebitis after intravenous use.
May produce condition similar to foetal alcohol syndrome including
cleft lip and palate.
Drug dependence.
Sexual fantasy.
Drug interactions
There is synergy with all CNS depressant drugs (including alcohol
and opioid analgesics) leading to an enhanced effect and thus combined
use is best avoided. The antidepressant drugs fluoxetine and
fluvoxamine enhance the effects of diazepam. Severe hypotension and
respiratory depression may occur when diazepam is administered
simultaneously with the antipsychotic drug clozapine and combined
therapy is not recommended.
Cimetidine and omeprazole inhibit the metabolism of diazepam,
thus increasing its sedative effect. In addition the gut motility stimulant
cisapride and the anti-emetic drug metoclopramide enhance the
action of oral diazepam. Similarly, oral contraceptives, the antialcohol
drug disulfiram, the muscle relaxant baclofen, and the cannabinoid
nabilone all increase the effect of diazepam. Beta-adrenergic
drugs reduce metabolism of diazepam but there appears to be little
clinical risk from combined therapy. Similarly, although paracetamol
reduces the excretion of diazepam this is of no clinical importance.
The antibacterials isoniazid and ciprofloxacin inhibit the metabolism
of diazepam whereas rifampicin increases metabolism of the
benzodiazepine. Smoking increases the metabolism of diazepam.
Diazepam affects the metabolism of phenytoin in an inconsistent
manner, in some individuals the anticonvulsant plasma level is
increased in others it is reduced. Carbamazepine possibly reduces the
effects of diazepam, whereas sodium valproate enhances the effect of
the benzodiazepine.
Diazepam can increase the effects of neuromuscular blockers
tubocurarine, vecuronium, and atracurium. It reduces the effects of
levodopa. Diazepam may increase the plasma concentration of the
local anaesthetic bupivacaine. Flumazenil antagonizes the action of
diazepam. Aminophylline also has some antagonistic properties.
Caffeine can counteract some of the hypnotic effects of diazepam.
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Epinephrine = (adrenaline)
Description
A catecholamine sympathomimetic agent.
Indications
Used in dental local anaesthetic solutions to increase their efficacy
and duration and to aid in haemostasis.
Presentations
Epinephrine is contained in local anaesthetic solutions in concentrations
of 1 : 80,000 (12.5 g/mL), 1 : 100,000 (10 g/mL) and 1 :
200,000 (5 g/mL).
Dose
The maximum recommended dose over one visit in dental local
anaesthetic solutions is 200 g.
Contraindications
Severe cardiac disease such as uncontrolled arrhythmias and unstable
angina are contraindications to the use of epinephrine. The unusual
catecholamine-secreting tumour of the adrenal gland known as
phaeochromocytoma and thyroid storm (an acute hyperthyroid
episode) are other contraindications to epinephrine in dental local
anaesthesia.
Precautions
Dose reduction is wise when cardiac disease exists (see also drug
interactions below).
Unwanted effects
Excessive dosage or inadvertent intravascular injection will produce
symptoms of fear and anxiety such as tachycardia and tremors.
Systolic blood pressure can rise and diastolic blood pressure may
fall. Epinephrine, even at doses used in dentistry, can produce a
hypokalaemia (reduction in plasma potassium) and this can lead to
cardiac arrhythmias.
Drug interactions
Many drug interactions with epinephrine are theoretical, however
some have been shown to produce effects that are clinically important.
Tricyclic antidepressant drugs increase the pressor effects of
epinephrine twofold; as the pressor effects are negligible at the doses
used in dental local anaesthetics then simple dose reduction is all
that is required.
Adrenergic beta-blocking drugs such as propranolol can lead to
unopposed increases in systolic blood pressure and dose reduction of
epinephrine-containing local anaesthetics is advised. Non-potassium
sparing diuretics exacerbate the hypokalaemia produced by epinephrine
and this is apparent at the doses used in dental local anaesthesia;
thus for patients receiving such diuretic therapy epinephrine dose
reduction is advised. The volatile anaesthetics such as halothane
increase cardiac sensitivity to the effects of epinephrine and a 50%
dose reduction in the amount of catecholamine used is advised. Any
agent with sympathomimetic properties has the potential to increase
the toxicity of epinephrine and among these agents are drugs of
abuse such as cocaine, cannabis, and amphetamines.
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