Overdose of drugs by Prof Dr Shahzad Manzoor

1. DR.PROF. MUHAMMAD SHEHZAD MANZOOR

3. Antipsychotics

4.  Conventional
antipsychotics
 Chlorpromazin
e
 Haloperidol
 Droperidol
 Atypical
antipsychotics
 Risperidone
 Olanzapine
 Ziprasidone
 Quetiapine
 aripiprazole

5.  mainly act on CNS dopamine receptors
 atypical drugs also interact with
serotonin receptors
 prolongation of QRS or QT intervals
(or both) and can cause ventricular
arrhythmias. Among the atypical
agents, quetiapine is more likely
 to cause coma and hypotension.

6.  Therapeutic doses of conventional
phenothiazines
 induce drowsiness and mild
orthostatic hypotension in as many as
50% of patients.
 Larger doses can cause
 Miosis
 Severe hypotension
 Tachycardia
 Convulsions, and coma

7.  With therapeutic or toxic doses, an
acute extrapyramidal dystonic
reaction may develop in some
patients, with
 Spasmodic contractions of the face
and neck muscles,
 extensor rigidity of the back muscles,
carpopedal spasm,
 Motor restlessness.
 .

8.  Severe rigidity accompanied by
hyperthermia and metabolic
acidosis
 (“neuroleptic malignant
syndrome”)
 may occasionally
 occur and is life-threatening .

9.  Atypical antipsychotics have also
been associated with weight gain
 and diabetes mellitus, including
diabetic ketoacidosis.

10.  Administer activated charcoal for
large or recent ingestions.
 For severe hypotension, treatment
with intravenous fluids and
vasopressor agents may be necessary.
 Treat hyperthermia as outlined.
 Maintain ECG monitoring

11.  Prolongation of the QT interval and
torsades de pointes are usually
treated with intravenous magnesium
or
 overdrive pacing.
 For extrapyramidal signs, give
diphenhydramine,
 0.5–1 mg/kg intravenously, or
benztropine mesylate, 0.01–0.02
mg/kg intramuscularly.

12.  Bromocriptine (2.5–7.5 mg orally
daily) may be effective for mild or
moderate neuroleptic malignant
syndrome.
 Dantrolene (2–5 mg/kg intravenously)
has also been used
 For severe hyperthermia, rapid
neuromuscular paralysis is preferred.

13. ANTIDIBAETIC
DRUGS

14.  Edications used for diabetes mellitus
 Insulin
 Sulfonylureas and other
 Insulin secretagogues
 Alpha-glucosidase inhibitors (acarbose,
miglitol), biguanides (metformin),
 Thiazolidinediones (pioglitazone,
rosiglitazone)
 Sodium glucose transporter (SGLT2)
inhibitors, and peptide analogs (pramlintide,
exenatide) or enhancers (sitagliptin)

15. Insulin and the insulin secretagogue
are the most likely to cause hypoglycemia.
 Metformin cancause lactic acidosis,
especially in patients with impaired
kidney function or after intentional drug
overdose
 Hypoglycemia may occur quickly after
injection of short acting insulins or may
be delayed and prolonged

16.  Give sugar and carbohydrate-
containing food or liquids by mouth,
or intravenous dextrose if the patient
is unable to swallow safely. For severe
hypoglycemia, start with D50W,50 mL
intravenously (25 g dextrose)
 Consider hemodialysis for patients
with metformin overdose
accompanied by severe lactic acidosis

17. DRUGS ACTING
ON CVS

18.  Cardiac glycosides paralyze the Na+-
K+ -ATPase pump and have potent
vagotonic effects. Intracellular effects
include
 Enhancement of calcium-dependent
contractility and
 Shortening of the action potential
duration

19. nausea and vomiting
bradycardia
hyperkalemia
AV block frequently occur

20.  After acute ingestion, administer activated
charcoal.
 Monitor potassium levels and cardiac rhythm
closely.
 Treat bradycardia initially with atropine (0.5–2
mg intravenously) or a transcutaneous external
cardiac pacemaker. Specific Treatment
 For patients with significant intoxication,
administer digoxin-specific antibodies (digoxin
immune Fab [ovine];DigiFab)

21. CALCIUM CHANNEL
BLOCKERS

22.  In therapeutic doses, nifedipine, nicardipine,
amlodipine,felodipine, isradipine, nisoldipine,
and nimodipine act mainly on blood vessels,
 while verapamil and diltiazem act
 mainly on cardiac contractility and
conduction.

23.  Bradycardia
 Atrioventricular (AV) nodal block
 Hypotension, or a combination of these
 effects.
 Hyperglycemia is common due to blockade of
insulin release.
 With severe poisoning, cardiac arrest may
occur

24.  For ingested drugs, administer
activated charcoal. In addition, whole
bowel irrigation should be initiated as
soon as possible if the patient has
ingested a sustained-release product.

25.  Treat symptomatic bradycardia with
atropine (0.5–2 mg intravenously),
isoproterenol (2–20 mcg/min by
intravenous infusion), or a
transcutaneous cardiac pacemaker.
 For hypotension, give calcium
chloride 10%, 10 mL, or calcium
gluconate 10%, 20 mL. Repeat the
dose every 3–5 minutes.

26. BETA
BLOCKER

27.  hypotension and bradycardia. Cardiac
depression from more severe poisoning
is often unresponsive to therapy with
beta-adrenergic stimulants such
 seizures and coma may occur.
 conduction disturbance (wide QRS
interval) similar to tricyclic
antidepressant overdose.

28.  Attempts to treat bradycardia or heart
block with atropine
 (0.5–2 mg intravenously),
 Isoproterenol (2–20 mcg/min by
intravenous infusion, titrated to the
desired heart rate), or an
 external transcutaneous cardiac
pacemaker

29.  Give Glucagon 5–10 mg intravenously,
followed by an infusion of 1–5 mg/h.
 Glucagon is an inotropic agent that
acts at a different receptor site and is
therefore not affected by beta-
blockade. High dose insulin (0.5–1
unit/kg/h intravenously) along with
glucose supplementation has also
been used to reverse severe
cardiotoxicity.

30. TRICYCLIC
ANTIDEPRESSANTS

31.  Tricyclic and related cyclic
antidepressants are among the most
dangerous drugs involved in suicidal
overdose.
 These drugs have anticholinergic and
cardiac depressant proper ties
(“quinidine-like” sodium channel
blockade).
 Cardiotoxic effects

32.  Signs of severe intoxication may occur
abruptly and with out warning within 30–60
minutes after acute tricyclic overdose.
Anticholinergic effects include:
 Dilated pupils,
 tachycardia, dry mouth, flushed skin,
muscle twitching,
 and decreased peristalsis.

33.  Quinidine-like cardiotoxic effects
include QRS interval widening (greater than
0.12 s;
 ventricular arrhythmias
 AV block,
 hypotension.
 Rightward-axis deviation
 Prolongation of the QT interval and
torsades de pointes have been reported
 Seizures and
 Hyperthermia may result from status
epilepticus and anticholinergic-induced
impairment of sweating.

34.  Serotonin syndrome should be
suspected if agitation,delirium,
diaphoresis, tremor, hyperreflexia,
clonus (spontaneous, inducible, or
ocular), and fever develop in a patient
taking serotonin reuptake inhibitors.

35.  Observe patients for at least 6 hours
and admit all patients with evidence of
anticholinergic effects
Administer activated charcoal and
 Consider Gastric lavage after recent large
ingestions. All of these drugs have
 large volumes of distribution and are not
effectively removed by hemodialysis
procedures.

36.  »
• Boluses of sodium bicarbonate (50–100 mEq
intravenously). Sodium bicarbonate provides
a large sodium load that alleviates
depression of the sodium-dependent
channel
• Prolongation of the QT interval or torsades
de pointes is usually treated with
intravenous magnesium or overdrive pacing.
• Mild serotonin syndrome may be treated
with benzodiazepines and withdrawal of the
antidepressant.

37.  Severe hyperthermia should be treated
with neuromuscular paralysis and
endotracheal intubation in addition to
external cooling measures