EPIDEMIOLOGY AND AETIOLOGY.

Acne vulgaris is a chronic inflammatory disease of the pilosebaceous unit.
It is characterised by seborrhoea, non-inflammatory and inflammatory lesions, and scarring.
Almost all teenagers can expect some degree of acne, with moderate to severe disease in about 15% of those aged 15 to 17 years.

Acne develops earlier in girls, but more boys are affected. Late-onset acne (>25 years) is seen in 8% of patients and significant lesions are seen in 1% of men and 5% of women at the age of 40 years.

Aetiology

Three main factors are involved in the development of the condition:
Increased sebum (dependent on androgen drive or increased androgen receptor sensitivity)
Abnormal keratinisation
Colonisation of pilosebaceous duct by Propionibacterium acnes

Inflammation

Genetic factors play a part. There is a high concordance between monozygotic twins and a greater risk of severity is associated with a positive family history, maternal acne being associated with the greatest risk.

Acne is associated with increased insulin resistance and high serum dehydroepiandrosterone, which may explain its association with polycystic ovary syndrome (PCOS).
Abnormal androgen production drives acne in Cushing’s syndrome, congenital adrenal hyperplasia, patients using anabolic steroids and virilising tumours in females.

Factors that can cause acne to flare include menstruation, emotional stress, picking and smoking.

Most commonly, combinations are used to address comedonal and inflammatory components.

SUMMARY OF ACNE TREATMENT
The treatment of patients with acne is based on disease severity and extent

Mild acne
Comedonal – Topical retinoid
Papulopustular- Topical retinoid + BPO/topical antibiotic/azelaic acid

Moderate acne
Papulopustular/nodular- Male: Oral antibiotic + BPO +/topical retinoid
Female: Oral antibiotic + BPO +/topical retinoid +/combined oral contraceptive orspironolactone

Severe acne
Nodulocystic or unresponsive to antibiotics — Oral isotretinoin. If female, add combined oral contraceptive.

Mild acne- Treatments Explained.

Topical retinoids (for example, adapalene, tretinoin) are antiproliferative and used to treat comedonal acne. Available as gels and creams, they should be applied once or twice daily. They are recommended first-line for maintenance and can be continued indefinitely and combined with topical antibiotics or benzoyl peroxide (BPO).
All retinoids are contraindicated in pregnancy.

BPO, a non-antibiotic antimicrobial agent, can be used on its own or in combination for mild acne.
BPO (2.5-5% strength) should be started at a low frequency (such as three times a week) and titrated up to daily use, to reduce irritation.

Topical antibiotics, such as clindamycin and erythromycin, are commonly used, but monotherapy should be avoided to prevent resistance developing. Topical antibiotics should be combined with BPO or a retinoid for best results.
Topical azelaic acid can be used alone or with a topical retinoid for mild papulopustular disease.

Moderate acne
The key to success in moderate acne is to combine treatments to treat both the comedonal and the inflammatory components.
A typical combination is an oral antibiotic with a topical retinoid and BPO. Tetracyclines are usually used first-line, in particular lymecycline and doxycycline, both of which offer the added convenience of once-daily dosing.

Minocycline is best avoided because it has a higher incidence of adverse effects compared with other tetracyclines.
Oral erythromycin (500mg twice daily) or trimethoprim (300mg twice daily) are useful alternatives. Resistance to oral antibiotics can be minimised by using topical BPO concurrently.

In young women requiring contraception or with features of PCOS, an anti-androgenic combined oral contraceptive is recommended as part of combination therapy (with or without an oral antibiotic), along with a topical agent.

In older women, or if estrogens need to be avoided, spironolactone is an alternative when used with contraception.

Severe acne

Severe acne includes nodulocystic acne and acne that has failed to respond to at least two categories of oral antibiotics.
In such patients, oral isotretinoin is most effective, inducing long-term remission in about 90% of cases. Isotretinoin significantly reduces sebum production, prevents comedone formation, reduces P acnescolonisation and is anti-inflammatory.
It is usually prescribed in secondary care, owing to its side-effects and teratogenicity. Women of childbearing age must use contraception during and after treatment.

Antibiotic resistance
Increasing concern about antibiotic resistance has driven attempts to limit the frequency and duration of antibiotic use in patients with acne.
Resistance manifests in acne as reduced/no response or relapse. BPO is strongly bactericidal and its addition to antibiotic therapy minimises resistance at sites of application.

Light and laser therapy can improve inflammatory acne in the short term. Pain, erythema, swelling and hyperpigmentation are common side-effects. More comparative data and longer outcome studies are needed to define their role.

Common topical tretinoin side-effects
Stinging, burning or irritation, dryness, redness and peeling
Light or dark patches on your skin.

Dr G Mohan.

Continued on Acne Vulgaris Clinical Review at: http://www.tnmgc.com/discus/viewtopic.php?f=17&t=55