Pharmacology- Lice Flashcards
What is the name of lice in biology?
Pediculus humanus
What are the actions of lice?
Lice feed by piercing the skin and sucking blood from their host. This feeding can cause irritation, itching, and discomfort for the host.
They cling to hair shadts by crawling ( they dont fly)
Travel quicikly and highly contagous
What are the three types of lice?
Head lice - Pediculus humanus capitis
Body lice- Pediculus humanus humanus
Pubic lice(crabs): Phthirus pubis
What are symtoms of head lice?
Itching of scalp
Difficulty sleeping
Scatching ( may cause bacterial infection)
Raised bumps on neck
How is head lice diagnosed?
By visual inspection of scalp or wet comb and paper.
What gender has higher risk of lice and why?
Females (girls) as they have longer hair.
How to avoid lice
Avoid sharing brushes, comba, hats
Keep long hair tied up
Wash bed linens, hats, and clothing that may have come into contact with an infested person in hot water and dry them on high heat.
What are non pharmacological treatments of lice?
Wet combing (physical removal)
Applying olive oil or coconut oil to the hair and leaving it on overnight can help suffocate and loosen lice and nits.
Vinegar may help dissolve the glue that attaches nits to the hair shaft.
Vacuum your home, particularly areas where infested individuals spend time.
What are pharmacological treatment for head lice?
Used for 8-12 hours
Dimeticone lotion 4%
– does not kill live eggs – Benzyl alcohol emulsion 25%
– does not kill live eggs – Malathion lotion 0.5%
• partially ovicidal
What head lice medicine is not used in UK?
Lindane shampoo 1%
Can cause neurological damage/ death
How does Dimeticone work?
Dimeticone is applied to the hair and scalp in the form of a lotion or gel. When it comes into contact with lice, it forms a thick, silicone-based coating around them. This coating effectively suffocates the lice by blocking their spiracles (tiny openings used for breathing).
It is a silicon based medicine which forms water impervious coat if silicon on lice which suffocates them.
How does Benzyl alcohol works for treatment of headlice?
Benzyl alcohol works by suffocating the lice. When applied to the hair and scalp, it penetrates the respiratory system of the lice, blocking their spiracles (small openings used for breathing). This effectively deprives the lice of oxygen, leading to their death.
How does Malathoin works ?
Malathion is an organophosphorus compound that acts as an anticholinesterase agent.
It works by irreversibly inhibiting the enzyme cholinesterase, which is necessary for breaking down acetylcholine in the nervous system.
By blocking cholinesterase, malathion causes an accumulation of acetylcholine, leading to overstimulation of cholinergic receptors.
This results in continuous post-ganglionic neuronal excitation and prolonged muscle contraction, which can lead to paralysis and death in insects.
It is neurotoxic and is used as an insecticide. When used on humans for treating lice, it can be irritating to the skin and scalp, and it’s recommended not to exceed four consecutive applications to prevent adverse effects.
What is the action of anticholinesterase?
Normally, acetylcholinesterase breaks down acetylcholine to terminate the signal at a synapse. Anticholinesterase inhibits this enzyme, causing an accumulation of acetylcholine, which leads to prolonged stimulation of the target tissue. This can result in overstimulation, potentially causing toxic effects.
What are contraindications of malathoin?
Malathion generally has low toxicity to humans, but this is not the case with repeated exposure or overdose.
Ingestion and subsequent metabolism can lead to the conversion of malathion to malaoxon, which is far more toxic.
Chlorination of water can promote the oxidation of malathion to malaoxon.
What is the anticholinesterase effects of malathion in humans ?
Parasympathomimetic effects, which promote muscarinic neurotransmission.
Neuromuscular effects, which promote nicotinic transmission at skeletal muscles.
Central nervous system effects, which promote central cholinergic neurotransmission.
What does malathion/ malaoxone poisoning include? Parasympathetic
Miosis ( pupilary constriction)
Salivation
Sweating
Bradycardia ( slowing heart rate)
Malathion/Malaoxon poisoning Nicotinic skeletal muscle effects include:
Fasciculation (twitching of skeletal muscle)
Significant release of ACh
Paralysis - depolirizing neuromuscular block
Malathion/Malaoxon poisoning CNS effects include
anxiety
– restlessness
– Dizziness
How does lidane work?
Lindane acts as a gamma-hexachlorocyclohexane, which is a neurological toxin.
It binds to and inhibits the GABA_A chloride channel complex. GABA (gamma-aminobutyric acid) is an inhibitory neurotransmitter in the central nervous system. By inhibiting this channel, lindane prevents the influx of chloride ions, which normally results in the hyperpolarization (inhibition) of neuronal activity.
The inhibition of GABAergic neurotransmission by lindane causes hyperexcitation of the lice’s nervous system, leading to seizures and death.
What are Malathion & Lindane identified as?
Both are identified as neurotoxic insecticides, meaning they can damage the nervous system of both lice and humans as their treatment should be carefully considered.
What is pubic lice?
Pubic lice are small parasitic insects that infest the coarse hair of the human genital area, including the pubic region, but they can also infest other coarse body hair, such as in the armpits, chest, and even eyelashes and eyebrows
Symptoms of pubic lice?
itching and discomfort in the affected area. The itching is typically the result of an allergic reaction to the lice bites.
Black powder in underwear
Tiny blood spots on underwear
How is pubic lice diagnosed?
By visual detection ( physical examination)
