Dermatologic Medications

Introduction

• The lecture provides an in-depth overview of dermatological medications, stressing the significance of understanding specific drugs, their potential side effects, and how they are classified.

• The medications discussed will be selected based on key highlights from the recommended textbook.

Administration of Skin Medications

• Skin conditions can be addressed through topical (local) treatments, which involve applying medication directly to the affected area, or internal treatments for systemic effects, where the medication affects the entire body.

• Topical treatments typically include creams, ointments, lotions, and solutions that are applied directly to the skin.

• Internal treatments primarily involve oral medications. For instance, prednisone, a corticosteroid, may be prescribed orally to manage severe skin inflammations or allergic reactions.

Classification of Topical Skin Preparations

• Topical skin preparations are categorized into nine main classes based on their function:

  • Antipruritics: These medications are used to relieve itching caused by various skin conditions.

  • Corticosteroids: These are utilized to treat dermatological disorders that are associated with allergic reactions or inflammation. They come in varying potencies, and prolonged use requires monitoring due to potential side effects.

  • Emollients and Protectants: These agents are designed to soothe skin irritation, provide a protective barrier, and help to moisturize the skin.

  • Keratolytics: These medications help in loosening and shedding the outer epithelial layers of the skin, addressing conditions characterized by scaling or thickening of the skin.

  • Enzymatic Agents: These preparations facilitate the removal of dead or necrotic tissue from the skin, which is especially useful in wound care.

  • Scabicides and Pediculicides: These are used to treat infestations of scabies (mites) and pediculosis (lice), respectively.

  • Local Anti-Infectives: This category includes drugs that combat fungal, viral, and bacterial infections affecting the skin.

  • Burn Medications: The main aim of these medications is to prevent infection in burn injuries, which can significantly impede healing and cause complications.

  • Acne Agents: These medications are formulated to treat acne, addressing various factors contributing to the condition, such as reducing oil production or fighting bacterial infection.

Burn Medications

• The primary objective in treating burns is to prevent infection, which is a major risk due to the compromised skin barrier.

• Silver sulfadiazine (Silvadene) is a widely used topical cream for burns because of the anti-infective properties of silver, which inhibits bacterial growth.

• Silvadene is produced synthetically to provide a stable and effective means of preventing infections in burn wounds, thus promoting healing.

• It is important to apply Silvadene carefully, avoiding contact with healthy skin or clothing, as it can cause permanent black stains.

Factors Influencing Absorption

• Absorption rates of topical medications can vary depending on several factors:

  • Condition and location of the skin: Broken or inflamed skin may absorb more medication than intact skin. The location of application also matters, as some areas of the body absorb medications more readily than others.

  • Heat and moisture: Increased skin temperature and moisture can enhance absorption.

  • Skin thickness and presence of calluses: Thicker skin and calluses can impede absorption, requiring more potent formulations or application methods.

• Thick, calloused skin might necessitate the use of more potent treatments or special application techniques to ensure adequate medication absorption.

• Occlusion, which involves covering the treated area with an occlusive dressing like plastic wrap, can significantly enhance medication absorption by increasing hydration and penetration.

Antipruritics

• Antipruritics offer short-term relief from itching associated with conditions like dermatitis, poison ivy reactions, hives, and insect bites.

• Common active ingredients in antipruritics include:

  • Lidocaine and benzocaine: Local anesthetics that numb the area to reduce itching.

  • Calamine: An anti-itch medication that also has mild astringent properties.

  • Hydrocortisone: A corticosteroid that reduces inflammation and itching.

• Oral antihistamines are prescribed for systemic effects to alleviate itching by blocking histamine release.

• Topical antihistamines can lead to hypersensitivity reactions with prolonged use, causing further irritation or allergic contact dermatitis.

• Adverse effects of antipruritics may include:

  • Skin irritation, stinging, or burning sensations at the application site.

  • Sedation as a result of antihistamine components or, conversely, paradoxical agitation, particularly in children.

• Antipruritics containing cortisone can delay wound healing because cortisone has immunosuppressive effects.

Patient Education for Antipruritics

• Before applying antipruritics, the affected area should be cleaned thoroughly to remove any potential irritants or debris.

• The medication should be rubbed in gently until it is fully absorbed into the skin.

• Patients should be advised to use antipruritics cautiously if they have known allergies to any of the ingredients.

• Contact with eyes and mucous membranes should be avoided to prevent irritation.

• The treated area should not be covered with dressings unless specifically directed by a healthcare provider, as some conditions benefit from air exposure.

• Usage should be limited to no more than one week to avoid potential side effects or complications.

• Patients should discontinue use and consult their healthcare provider if the problem worsens or if new symptoms develop.

• Cutting children's fingernails short can help prevent skin damage and infection from scratching.

Corticosteroids

• Corticosteroids are employed both topically and systemically to manage allergic reactions and inflammatory skin conditions, with varying degrees of potency depending on the severity of the condition.

• Overuse of corticosteroids, especially potent formulations, can lead to side effects, including:

  • Epidermal thinning: Making the skin more fragile and susceptible to injury.

  • Hyperglycemia and glycosuria: Elevated blood sugar levels and glucose in the urine due to systemic absorption.

  • Cushing's syndrome: A hormonal disorder that can result from prolonged exposure to high levels of corticosteroids.

• Corticosteroids should not be applied to open wounds because of the risk of increased absorption into the bloodstream, which can inhibit healing and increase the potential for systemic side effects.

• Systemic corticosteroids should not be discontinued abruptly to avoid causing adverse effects such as adrenal insufficiency or a flare-up of the underlying condition.

• Hypersensitivity to any component of the formulation is a contraindication for the use of corticosteroids.

Emollients and Protectants

• Emollients and protectants are designed to soothe, soften, and protect the skin while also sealing out wetness in minor dermatological conditions such as diaper rash and abrasions.

• These products work by:

  • Moistening the skin.

  • Providing a lipid barrier that helps to retain moisture and protect against irritants.

Keratolytics

• Keratolytics, like salicylic acid, are used to treat conditions with abnormal scaling of the skin, such as dandruff, seborrhea, and psoriasis.

• They function by promoting skin peeling, which aids in the treatment of:

  • Acne

  • Hard cones

  • Calluses

  • Warts

• Side effects can include severe skin irritation and irritation to the eyes or mucous membranes, especially if used improperly.

• Keratolytics should not be applied to open areas of the skin due to the risk of excessive absorption and irritation.

Enzyme Preparations

• Enzyme preparations are used to remove necrotic or fibrous tissue, particularly in bedridden patients with cubitus ulcers (pressure sores) and diabetic patients prone to foot ulcers.

• Collagenase is a topical enzyme ointment that facilitates chemical debridement, which involves removing dead tissue to promote healing and reduce the risk of infection.

Scabicides and Pediculicides

• Scabicides are used to treat scabies, a skin infestation caused by mites that burrow under the skin, leading to intense itching and rash.

• Pediculicides are used to treat pediculosis (lice) infestations affecting the pubic area, scalp, and trunk.

• Lindane lotion is a potent treatment option, but it may require multiple applications to fully eradicate the infestation.

• Permethrin is an alternative shampoo and cream used to treat lice infestations, often preferred due to its lower toxicity compared to lindane.

• Side effects of these treatments may include slight skin irritation, rash, or conjunctivitis.

• Lindane should be avoided on inflamed, raw, or weeping surfaces because of the potential for increased absorption into the bloodstream, which can cause neurotoxic effects.

• For patients who cannot tolerate or do not respond to first-line treatments, ivermectin may be considered as an alternative.

Local Anti-Infectives

• Local anti-infectives are used to treat skin diseases caused by microorganisms, including fungal, viral, and bacterial infections.

• Antifungals, such as nystatin, are effective against fungal infections like candida, which can cause diaper rash, vaginitis, and thrush.

• Other commonly used antifungals include clotrimazole, often used for treating athlete's foot, ringworm, and jock itch.

• Effective treatment strategies include keeping the area clean and dry and exposing it to air to inhibit fungal growth.

• Nystatin oral suspension is prescribed to treat oral thrush, a fungal infection of the mouth.

• Oral tablets like fluconazole are an alternative systemic treatment option for thrush, especially in patients with recurrent or severe infections.

• Patients using swish-and-swallow treatments should rinse their mouth before application and avoid eating or drinking for at least 30 minutes after use to allow the medication to remain in contact with the affected area.

Antivirals

• Acyclovir is an antiviral medication effective against herpes simplex virus (HSV) infections, including cold sores and genital herpes, as well as herpes zoster virus (HZV) infections, such as shingles and chickenpox.

• Acyclovir, also known as Zovirax, is available in various forms, including oral tablets, intravenous injections, and topical creams.

• Zovirax cream is used to treat cold sores by reducing the duration and severity of outbreaks, but it does not cure the underlying viral infection.

• Valtrex, a prodrug of acyclovir, is a once-a-day oral medication that can help manage outbreaks of herpes simplex virus if taken within 72 hours of symptom onset.

Antibacterial Agents

• Mupirocin (Bactroban) is an antibacterial agent used to treat skin infections caused by staphylococcus (staph) or streptococcus (strep) bacteria.

• It is effective in treating secondarily infected traumatic skin lesions and can also be applied in the nose to eliminate nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA).

Antiseptics

• Antiseptics like chlorhexidine (Hibiclens) are used to cleanse wounds and inhibit bacterial growth, helping to prevent infection.

• They should not be used on deep wounds, as they can interfere with the natural healing process and may cause irritation or tissue damage.

Burn Medications

• Burns can result from various causes, including heat from flames, hot liquids, steam, heated objects, chemicals, electricity, radiation, or overexposure to the sun.

• Treatment of burns involves topical applications of medications to prevent or treat infections associated with damaged skin, which is crucial for promoting healing and preventing complications.

• Commonly used agents include:

  • Silver sulfadiazine (Silvadene)

  • Mafenide (Sulfamylon), which are effective for second- and third-degree burns due to their broad-spectrum antimicrobial activity.

• Silver is considered naturally anti-infective because bacteria cannot thrive in its presence, making it an effective component in burn creams.

Sunscreen

• The use of sunscreen involves a balance between the need for sun exposure for vitamin D synthesis and overall health and the potential cancer-causing effects of both excessive sun exposure and certain chemicals found in sunscreens.

Agents for Acne

• Acne is a prevalent skin condition, especially among teenagers and young adults, characterized by the presence of pimples, blackheads, and inflammation.

• Isotretinoin (formerly marketed as Accutane) is a potent retinoid medication prescribed by dermatologists to decrease oil production and reduce inflammation, but it requires strict monitoring due to its potential adverse effects.

• Isotretinoin is typically reserved for severe acne cases that have not responded to other treatments, and patients must undergo pregnancy tests and adhere to strict contraception guidelines due to the risk of severe birth defects.

• Retinoids, including tretinoin, adapalene, and tazarotene, are taken by mouth or applied topically for the most severe forms of acne in patients who have failed other treatments, helping to unclog pores and reduce inflammation.

Drugs to Know (Summary Table)

• Permethrin:

  • Trade names: Acticin, Elimite

  • Classification: Scabicide, Pediculicide

• Clotrimazole:

  • Trade names: Lotrimin, Mycelex

  • Classification: Antifungal

• Ketoconazole:

  • Trade name: Nizoral

  • Classification: Antifungal

• Acyclovir:

  • Trade name: Zovirax

  • Classification: Antiviral

• Mupirocin:

  • Trade name: Bactroban

  • Classification: Antibacterial

  • Avoid contact with eyes.

• Isotretinoin:

  • Trade name: Claravis Acticin, Elimite

  • Classification: Acne Treatment

• Tretinoin:

  • Trade name: Retin-A

  • Classification: Acne Treatment