Introduction Pharmacotherapy: Permethrin, Malathion, Lindane, Ivermectin and cotrimoxazole Clinical problem.

1. Pharmacotherapy of
Pediculosis
Dr.Uma Advani
Assistant Professor Pharmacology,
SMS,MC Jaipur

2. Learning objectives:
Introduction
Pharmacotherapy:
Permethrin,
Malathion,
Lindane,
Ivermectin and cotrimoxazole
Clinical problem.

3. • Pediculosis capitis or head lice is a world
wide public health concern
• Affects persons of all ages and
socioeconomic backgrounds.
• Causative organism – Pediculus humanus
capitis.
• Obligate ectoparasite that lives on human
hair and feeds on blood from the skin.
• Most common in school aged children and
girls are affected more often than boys.

4. • Transmission occurs through close contact
especially head to head contact.
• Adult louse feds 4 – 5 times a day and can
normally survive for only 1 –2 days away
from the scalp.
• Lice typically lay eggs within 2 – 4 mm of
the scalp base attaching to the hair.
• The young louse hatches 6 to 10 days later
leaving the egg shell behind.
• Dead eggs and eggshells (nits) can remain
attached to the hair as long as 6 months.

5. • Dead eggs and eggshells (nits) can remain
attached to the hair as long as 6 months.
So
what?

6. • Diagnosis and treatment of an active louse
infestation should be based on the
detection of living lice.
• No treatment should be initiated if living
lice are not found on the scalp.
Answer

7. • Has pediculicidal and ovicidal activity
• Blocks sodium channel repolarization in the
louse neuron resulting in respiratory paralysis
and death.
• Remains active for 2 weeks following
application.
• Instructions : after washing hair, rinsing with
water and towel drying, it is applied to the
hair for 10 minutes and then rinsed out.
Permethrin

8. • Why should the hair be dried
before applying permethrin?

9. • Ans : Lice can close down
their respiratory airways for
30 minutes when immersed
in water.

10. • Permethrin is not 100 % ovicidal . So a higher
cure rate may be obtained by a second
application 1 week after the first treatment.
• Cream rinses and conditioning shampoos coat
the hair and so will protect the lice . Hence
they should be avoided for 2 weeks after
treatment.
Permethrin

11. • It is an organophosphate cholinesterase
inhibitor .
• Causes respiratory paralysis of the louse.
• Fast acting pediculicide with high ovicidal
activity.
• Residual effect is seen because it can bind to
the sulfur atoms of the hair.
Malathion

12. • To be applied for 10 minutes or overnight and
repeated in 1 week .
• Has an unappealing odour.
• Causes stinging of the skin and eyes.
• Resistance to malathion observed with
repeated use.
Malathion

13. • Second line agent due to its neurotoxicity and
bone marrow suppression.
• Used when patient is intolerant to permethrin.
• Advantage : cheaper
Lindane

14. • MOA: causes paralysis and death of lice.
• Can be used after failure with topical
pediculicides.
• Useful for extensive infestations or
infestations with multiple ectoparasites.
• An acceptable form of treatment for contacts .
Ivermectin

15. • Shown to be effective in small scale studies.
• Probable mechanism of action: destroys the
gut flora of louse thereby interfering with its
ability to synthesize vitamin B12 and thereby
causing death.
• Can be combined with topical therapy.
Cotrimoxazole

16. Exoskeleton integrity dehydration
pediculicides
• a combination of isopropyl myristate and ST
cyclomethicone. Effective in Phase 2 trials
so far.
• Acts by dissolving the waxy exoskeleton of
the louse, dehydrating them and eventually
leading to death.

17. • A 50 year old woman was treated with
topical permethrin lotion (1%) after being
diagnosed with Scabies . Inspite of having
repeated treatment on 4 occasions over a
period of 6 months there was no
improvement of her condition. What could
be the possible reason?

18. Answer
• Scabies - Permethrin cream (5%)
• Pediculosis – Permethrin lotion (1%)

19. Thank you.