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0.025 %; both formulations have been shown to be efficacious at treating mild to moderate acne . 17 Trifarotene is a new topical retinoid recently launched in Australia that is the only selective retinoic acid receptor gamma inhibitor ; retinoic acid receptor-gamma is thought to be a leading contributor to acne . No head-to-head trials with trifarotene have been published . 18

In patients presenting with papulopustular acne with a more pronounced inflammatory component , controlling the propagation of C . acnes is an important treatment target . Topical antibiotics are useful adjuncts in inhibiting the proliferation of C . acnes but are rarely used alone because of the risk of antibiotic resistance and their single mechanism of action . 19

Benzoyl peroxide is a bactericidal agent with a lower risk of antibiotic resistance than topical antibiotics alone . 19 It has a modest keratolytic effect . Benzoyl peroxide containing products are available widely overthe-counter in various preparations and concentrations including gels and cleansers . In the case of truncal acne , or acne covering a large portion of body surface area , patients may find a daily benzoyl peroxide wash more efficient . However , benzoyl peroxide can cause skin bleaching ( and bleaching of clothing , towels and linen ) and should be used cautiously in patients with darker skin types . Rare cases of hypersensitivity to benzoyl peroxide have been reported , so advise patients to patch test before regular use . 20

All topical agents are irritants and can cause dermatitis and skin itching . Topical retinoids , in particular , can cause a retinoid dermatitis that may result in PIH in darker skin types . 22 This can be limited by introducing treatments at a low concentration and reduced dosing schedule , for example , weekly or every second or third day , until daily treatment is tolerated . Other strategies include applying the treatment on top of moisturiser , diluting with a moisturiser or washing the topical agent off after a period . Again , emphasise the importance of skin care and

Table 1 . Topical agents for treatment of acne vulgaris Treatment Mechanism Dose Indications Safe in pregnancy ?

Azelaic acid 15 % ( Finacea )

Azelaic acid 20 % ( Azclear )

Adapalene 0.1 % ( Differin )

Tretinoin 0.05 % ( Retrieve / Stieva-A ) Tretinoin 0.025 % ( Stieva-A )

Trifarotene ( Aklief )

Benzoyl peroxide 2.5 % or 5 %

Clindamycin solution

Keratolytic Antimicrobial agent Anti-inflammatory

Keratolytic Anti-inflammatory

Keratolytic Anti-inflammatory

Keratolytic Anti-inflammatory

Antimicrobial agent Anti-inflammatory

Antimicrobial agent Anti-inflammatory

maintaining the skin barrier with moisturiser to all patients .

Assess the treatment efficacy after three months . In the event of a poor response , topical combination therapies ( see box 4 ), which have been shown to improve treatment

Apply a thin , even layer twice daily

Apply a thin , even layer to dry skin weekly , then increase frequency as patient tolerates

Apply a thin , even layer to dry skin weekly , then increase frequency as patient tolerates

Apply a thin , even layer to dry skin weekly , then increase frequency as patient tolerates

Apply a thin , even layer daily

Apply a thin , even layer daily

outcomes , are available .

If acne persists despite treatment with combined topical therapy , an oral adjunct can be used ( see table 2 ). Prescribe oral antibiotics in combination with benzoyl peroxide to reduce antibiotic resistance . 23

Comedonal acne Concurrent PIH

Concurrent PIH

Concurrent PIH

Concurrent PIH

Inflammatory ( papulopustular ) acne

Usually prescribed in combination to prevent resistance

Source : Graupe K et al 1996 13 , Kircik LH 2011 14 , Zaenglein AL 2008 15 , Harper JC et al 2019 16 , New drug : Trifarotene for acne . Australian Prescriber 2021 18 , Eady EA et al 1994 19 , Chien AL et al 2016 21

Table 2 . Oral agents for the treatment of acne vulgaris Treatment Dose Contraindications Monitoring

Doxycycline ( first-line oral treatment )

100mg daily for three months

Pre-pubescent children Pregnancy

Combined oral contraceptive pill ( women )

Variable dependent on subtype

Source : Chien AL et al 2016 21 , Del Rosso JQ et al 2009 23 , Trivedi MK et al 2017 24

History of thrombophilia or thromboembolism Migraine with aura Known ischaemic heart disease or previous stroke Multiple cardiovascular risk factors Hypertension Severe liver disease Complicated diabetes mellitus

Yes

No

No

No

Yes

Yes

Generally not required Consider LFT monitoring for prolonged treatment

Baseline blood pressure EUC at baseline and after dose changes

Baseline blood pressure

In women with a hormonal component to their acne , that is , experiencing flares of acne consistently around menstrual cycles , treatment aimed at reducing excess androgen production may be beneficial . Changing the method of

Box 4 . Common combination topical therapies

• Adapalene 0.1 % with benzoyl peroxide 2.5 % gel ( Epiduo ).

• Adapalene 0.3 % with benzoyl peroxide 2.5 % gel ( Epiduo Forte ).

• Clindamycin 1 % with benzoyl peroxide 5 % gel ( Duac ).

• Clindamycin 1 % with tretinoin 0.025 % gel ( Acnatac ).

contraception to a combined oral contraceptive pill and / or initiating high-dose spironolactone are common strategies . 24 Versions of the combined oral contraceptive pill containing cyproterone acetate with ethinyloestradiol ( Diane-35 , Estelle-35 , Brenda-35 , or Juliet-35 ) or drospirenone with ethinyloestradiol ( Yasmin ) are particularly helpful in the treatment of acne because of the inclusion of a progestogen with anti-androgen activity . In pregnant women experiencing a flare of acne , start a pregnancy-safe topical treatment ; many of the oral agents are contraindicated in pregnancy . 21

Topical treatments for acne often suppress rather than cure the disease and patients may require longer term maintenance therapy to maintain an acceptable disease state .

Treatment of moderatesevere acne

Inflammatory acne , particularly the nodular subtype , is more likely to cause the long-lasting sequelae of scarring and post-inflammatory changes . 25 Patients often find the tender nature of the lesions and the disfiguring aspect of the disease particularly distressing . Patients who present with moderate-severe acne therefore often require multi-modal treatment . A three-month course of a combined topical agent in addition to oral doxycycline 100mg daily is considered first-line treatment . Other tetracycline antibiotics can be used as alternatives , and macrolides can be substituted in the case of contraindication or intolerance to tetracycline . 23

Intralesional injections of

Figure 2 . Papulopustular acne . Figure 3 . Nodulocystic acne .