Consumer medicine information

Duac Once Daily Gel

Clindamycin; Benzoyl peroxide

BRAND INFORMATION

Brand name

Duac Once Daily Gel

Active ingredient

Clindamycin; Benzoyl peroxide

Schedule

SUMMARY CMI

DUAC ONCE DAILY GEL

Consumer Medicine Information (CMI) summary

The full CMI on the next page has more details. If you are worried about using this medicine, speak to your doctor or pharmacist.

1. Why am I using DUAC ONCE DAILY GEL?

DUAC ONCE DAILY GEL contains the active ingredients clindamycin and benzoyl peroxide. DUAC ONCE DAILY GEL is used to treat acne.

For more information, see Section 1. Why am I using DUAC ONCE DAILY GEL? in the full CMI.

2. What should I know before I use DUAC ONCE DAILY GEL?

Do not use if you have ever had an allergic reaction to DUAC ONCE DAILY GEL or any of the ingredients listed at the end of the CMI.

Talk to your doctor if you have any other medical conditions, take any other medicines, or are pregnant or plan to become pregnant or are breastfeeding.

For more information, see Section 2. What should I know before I use DUAC ONCE DAILY GEL? in the full CMI.

3. What if I am taking other medicines?

Some medicines may interfere with DUAC ONCE DAILY GEL and affect how it works.

A list of these medicines is in Section 3. What if I am taking other medicines? in the full CMI.

4. How do I use DUAC ONCE DAILY GEL?

DUAC ONCE DAILY GEL should be applied once daily in the evening

More instructions can be found in Section 4. How do I use DUAC ONCE DAILY GEL? in the full CMI.

5. What should I know while using DUAC ONCE DAILY GEL?

Things you should do	Keep DUAC ONCE DAILY GEL away from your lips, eyes, mouth and other mucous membranes. Remind any doctor, dentist or pharmacist you visit that you are using DUAC ONCE DAILY GEL If you feel that DUAC ONCE DAILY GEL is not helping your condition, tell your doctor If you become pregnant or are breastfeeding while using DUAC ONCE DAILY GEL, tell your doctor
Things you should not do	Do not give DUAC ONCE DAILY GEL to anyone else, even if they have the same symptoms as yours Do not apply to any irritated areas of your skin; for example, cuts, grazes, sunburn or eczema
Looking after your medicine	Store in the refrigerator at 2°C to 8°C for up to 2 months Do not freeze

For more information, see Section 5. What should I know while using DUAC ONCE DAILY GEL? in the full CMI.

6. Are there any side effects?

Side effects which have been reported at the site of application include dry skin, discolouration of skin, skin peeling and pain, itching, burning sensation on skin, sensitivity to sunlight and redness of your skin, especially during the first few weeks of use. Other side effects which have been reported include headache, nausea, vomiting, diarrhoea including bloody diarrhoea and stomach pain.

For more information, including what to do if you have any side effects, see Section 6. Are there any side effects? in the full CMI.

FULL CMI

DUAC ONCE DAILY GEL

Active ingredient(s): clindamycin (as phosphate) and benzoyl peroxide

Consumer Medicine Information (CMI)

This leaflet provides important information about using DUAC ONCE DAILY GEL. You should also speak to your doctor or pharmacist if you would like further information or if you have any concerns or questions about using DUAC ONCE DAILY GEL.

Where to find information in this leaflet:

1. Why am I using DUAC ONCE DAILY GEL?
2. What should I know before I use DUAC ONCE DAILY GEL?
3. What if I am taking other medicines?
4. How do I use DUAC ONCE DAILY GEL?
5. What should I know while using DUAC ONCE DAILY GEL?
6. Are there any side effects?
7. Product details

1. Why am I using DUAC ONCE DAILY GEL?

DUAC ONCE DAILY GEL contains the active ingredients clindamycin and benzoyl peroxide. Clindamycin is an antibiotic, which prevents the growth of bacteria which are involved in acne. Benzoyl peroxide acts to reduce comedones (blackheads and whiteheads). It is also effective at killing the bacteria, which are involved in acne, and makes the skin less oily.

DUAC ONCE DAILY GEL is used on the skin to treat acne. It helps to:

reduce the bacteria or germs, which are implicated in acne;
reduce the number of acne spots;
reduce the likelihood of new blackheads and whiteheads from forming; and
make your skin less oily

DUAC ONCE DAILY GEL is for use by adults and adolescents (aged 12 and above) with acne.

DUAC ONCE DAILY GEL is not addictive.

2. What should I know before I use DUAC ONCE DAILY GEL?

Warnings

Do not use DUAC ONCE DAILY GEL if:

you are allergic to clindamycin and benzoyl peroxide or any of the ingredients listed at the end of this leaflet. Always check the ingredients to make sure you can use this medicine.
you have a known sensitivity to benzoyl peroxide, clindamycin or lincomycin.
you have or have ever had:
- regional enteritis (inflammation of the small intestine)
- colitis (inflammation of the large intestine)
- ulcerative colitis (inflammation which may be due to the presence of ulcers)
- antibiotic associated colitis (inflammation which may be associated with the past use of antibiotics)

Check with your doctor if you:

have any other medical conditions
are using other creams, ointments or lotions or are taking any medicines for any other condition
have used or taken any other clindamycin or erythromycin containing medicines recently

During treatment, you may be at risk of developing certain side effects. It is important you understand these risks and how to monitor for them. See additional information under Section 6. Are there any side effects?

Pregnancy and breastfeeding

Check with your doctor if you are pregnant or intend to become pregnant. Your doctor will discuss the risks and benefits of using DUAC ONCE DAILY GEL when pregnant.

Talk to your doctor if you are breastfeeding or intend to breastfeed. Your doctor will discuss the risks and benefits of using DUAC ONCE DAILY GEL when breast-feeding.

Do not apply DUAC ONCE DAILY GEL to the breasts before breastfeeding.

3. What if I am taking other medicines?

Tell your doctor or pharmacist if you are taking any other medicines, including any medicines, vitamins or supplements that you buy without a prescription from your pharmacy, supermarket or health food shop.

Some medicines may interfere with DUAC ONCE DAILY GEL and affect how it works.

These include:

medicated or abrasive soaps and cleansers;
chemical peels; and
cosmetic products that have a strong drying effect

These also include products containing:

erythromycin;
clindamycin;
lincomycin;
benzoyl peroxide;
tretinoin, isotretinoin or tazarotene;
salicylic acid;
alcohol

These medicines may have a cumulative irritant effect or affect how well DUAC ONCE DAILY GEL works. You may need to use different amounts of your medicine or you may need to use different medicines. Your doctor will advise you.

Check with your doctor or pharmacist if you are not sure about what medicines, vitamins or supplements you are taking and if these affect DUAC ONCE DAILY GEL.

4. How do I use DUAC ONCE DAILY GEL?

It is important to use DUAC ONCE DAILY GEL exactly as your doctor has told you.

Directions given to you by your doctor may differ from the information contained in this leaflet.

If you do not understand the instructions on the box, tube or this leaflet, ask your doctor or pharmacist for help.

Wash the affected area thoroughly and rinse with warm water. Lightly pat dry the skin.

Remove make-up thoroughly before applying the gel. After it has dried, you can use a non-greasy make-up.

How to apply DUAC ONCE DAILY GEL

DUAC ONCE DAILY GEL is for topical (external) use only
a thin film of gel should be applied to all of the area of the skin which has acne, not just the individual spots
as a guide, one fingertip (the amount of gel squeezed from the tube which reaches from the tip of your finger to the first joint) is enough to cover the face, two and one-half fingertips of gel will cover your face and back
if the gel does not rub into your skin easily, you are using too much
wash your hands after applying the gel

When to use DUAC ONCE DAILY GEL

DUAC ONCE DAILY GEL should be applied once daily in the evening
if you use DUAC ONCE DAILY GEL less often than you should, it may not work as well and your skin problem may not improve
using it more often than you should may not improve your skin problem any faster and may cause or increase side effects
it may take 4-6 weeks before you see the full effects of DUAC ONCE DAILY GEL on your acne
do not use DUAC ONCE DAILY GEL for more than 11 weeks unless your doctor tells you to
if you are not sure of how long you need to use DUAC ONCE DAILY GEL, talk to your doctor

If you forget to use DUAC ONCE DAILY GEL

If it is almost time for your next application of DUAC ONCE DAILY GEL, skip the application you missed and apply the gel when you are next meant to. Otherwise, use it as soon as you remember, and then go back to using your gel as you would normally.

Do not apply a double dose to make up for the dose that you missed.

If you have trouble remembering to use your medicine, ask your pharmacist for some hints.

If you swallow DUAC ONCE DAILY GEL

If you think that you or anyone else has swallowed DUAC ONCE DAILY GEL, you may need urgent medical attention.

You should immediately:

phone the Poisons Information Centre
(by calling 13 11 26), or
contact your doctor, or
go to the Emergency Department at your nearest hospital

You should do this even if there are no signs of discomfort or poisoning.

5. What should I know while using DUAC ONCE DAILY GEL?

Things you should do

If you feel that DUAC ONCE DAILY GEL is not helping your condition, tell your doctor.

Tell your doctor if for any reason, you have not used DUAC ONCE DAILY GEL exactly as prescribed. Otherwise, your doctor may think that it was not effective and change your treatment unnecessarily.

Keep DUAC ONCE DAILY GEL away from your lips, eyes, mouth and other mucous membranes.

Avoid excessive exposure to sunlight. Sunlamps should not be used. Avoid using at high altitudes or where the ground is snow-covered. When exposure to sunlight cannot be avoided, use a sunscreen product and wear protective clothing.

Call your doctor straight away if you:

become pregnant while using DUAC ONCE DAILY GEL
are breastfeeding while using DUAC ONCE DAILY GEL
develop stomach cramps or diarrhoea that does not improve or is severe - stop using DUAC ONCE DAILY GEL and contact your doctor immediately
Antibiotics may cause a condition that results in severe diarrhoea and stomach cramps. Although this is unlikely to happen with antibiotics applied to the skin

Remind any doctor, dentist or pharmacist you visit that you are using DUAC ONCE DAILY GEL.

Things you should not do

do not give DUAC ONCE DAILY GEL to anyone else, even if they have the same symptoms as yours
do not apply to any irritated areas of your skin; for example if you have cuts, grazes, sunburn or eczema.
do not use too much on your neck or other sensitive areas of the skin
do not use occlusive (air or watertight) dressings on areas treated with DUAC ONCE DAILY GEL unless necessary. Using occlusive dressing may increase irritation

DUAC ONCE DAILY GEL may bleach hair and coloured fabrics, such as clothing, towels and bed linen. Be careful to avoid contact of DUAC ONCE DAILY GEL with hair and coloured fabrics.

Looking after your medicine

store in the refrigerator at 2°C to 8°C for up to 2 months
do not freeze

Follow the instructions in the carton on how to take care of your medicine properly.

Store it in a cool dry place away from moisture, heat or sunlight; for example, do not store it:

in the bathroom or near a sink, or
in the car or on window sills.

Keep it where young children cannot reach it.

Getting rid of any unwanted medicine

If you no longer need to use this medicine or it is out of date, take it to any pharmacy for safe disposal.

Do not use this medicine after the expiry date.

6. Are there any side effects?

All medicines can have side effects. If you do experience any side effects, most of them are minor and temporary. However, some side effects may need medical attention.

See the information below and, if you need to, ask your doctor or pharmacist if you have any further questions about side effects.

Less serious side effects

Less serious side effects

What to do

Skin and subcutaneous tissue disorders:

dry skin
skin peeling
redness of your skin, especially during the first few weeks of use
skin burning sensation
itching
skin pain
sensitivity to sunlight
red, itchy skin, rash (dermatitis, erythematous rash)
worsening of acne
discoloration of the skin

Gastrointestinal disorders

nausea
vomiting
diarrhoea, including bloody diarrhoea
stomach pain

Nervous system disorders:

headache

Speak to your doctor if you have any of these less serious side effects and they worry you.

Serious side effects

Serious side effects

What to do

Skin and subcutaneous tissue disorders:

tingling (paraesthesia)
raised itchy rash (hives)
severe burning and peeling

Immune system disorders and allergic reactions:

allergic reactions

Call your doctor straight away, or go straight to the Emergency Department at your nearest hospital if you notice any of these serious side effects.

Tell your doctor or pharmacist if you notice anything else that may be making you feel unwell.

Other side effects not listed here may occur in some people.

Reporting side effects

After you have received medical advice for any side effects you experience, you can report side effects to the Therapeutic Goods Administration online at www.tga.gov.au/reporting-problems.

By reporting side effects, you can help provide more information on the safety of this medicine.

Always make sure you speak to your doctor or pharmacist before you decide to stop taking any of your medicines.

7. Product details

This medicine is only available with a doctor's prescription.

What DUAC ONCE DAILY GEL contains

Active ingredient (main ingredient)	clindamycin 1% w/w (as phosphate) benzoyl peroxide 5% w/w.
Other ingredients (inactive ingredients)	carbomer 980 dimeticone 100 disodium lauryl sulfosuccinate disodium edetate glycerol silicon dioxide poloxamer purified water sodium hydroxide

Do not take this medicine if you are allergic to any of these ingredients.

What DUAC ONCE DAILY GEL looks like

DUAC ONCE DAILY GEL is a white to slightly yellow gel that is available in a 25 g or 30 g tube (AUST R 100707)

A 5 g sample tube is also available from your physician only.

Not all pack sizes may be available.

Who distributes DUAC ONCE DAILY GEL

GlaxoSmithKline Australia Pty Ltd
Level 4, 436 Johnston Street,
Abbotsford, Victoria, 3067
Phone: 1800 033 109
www.gsk.com.au

Trade marks are owned by or licensed to the GSK group of companies.

This leaflet was prepared in January 2025.

Version 7.0

Published by MIMS March 2025

BRAND INFORMATION

Brand name

Duac Once Daily Gel

Active ingredient

Clindamycin; Benzoyl peroxide

Schedule

1 Name of Medicine

Benzoyl peroxide/ clindamycin phosphate.

2 Qualitative and Quantitative Composition

Duac Once Daily Gel contains clindamycin 1% w/w (as phosphate) and benzoyl peroxide 5% w/w. The product is presented in internally, lacquered membrane-sealed aluminium tubes fitted with a polyethylene screw cap.
Duac Once Daily Gel contains 10 mg/g (1% w/w) clindamycin (as phosphate) and 50 mg/g (5% w/w) benzoyl peroxide.
For the full list of excipients, see Section 6.1 List of Excipients.

3 Pharmaceutical Form

Duac Once Daily Gel is a white to slightly yellow homogenous gel for topical use.

4 Clinical Particulars

4.1 Therapeutic Indications

For the topical treatment of comedo, papular and pustular acne vulgaris.

4.2 Dose and Method of Administration

Duac Once Daily Gel is for topical (external) use only.
Duac Once Daily Gel is recommended for a maximum duration of treatment of 11 weeks.

Adults and adolescents (aged 12 years and above).

Duac Once Daily Gel should be applied as a thin film once daily in the evening, to affected areas after the skin has been thoroughly washed, rinsed with warm water and gently patted dry.
See Section 4.5 Interactions with Other Medicines and Other Forms of Interactions; Section 4.9 Overdose for temporary interruptions or discontinuations of the treatment.

Use in children.

The safety and efficacy of Duac Once Daily Gel has not been established in prepubescent children (under 12 years of age), since acne vulgaris rarely presents in this age group.

4.3 Contraindications

Duac Once Daily Gel is contraindicated in patients who have demonstrated hypersensitivity to lincomycin, clindamycin, benzoyl peroxide or any components of the formulation; patients with, or with a history of regional enteritis, ulcerative colitis, or antibiotic associated colitis (including pseudomembranous colitis).

4.4 Special Warnings and Precautions for Use

Hypersensitivity reaction.

If the patient experiences a reaction that indicates contact hypersensitivity or severe irritation, treatment with Duac Once Daily Gel should be discontinued immediately.
For dermatological (external) use only. Contact with the mouth, eyes, lips, other mucous membranes or areas of irritated or broken skin should be avoided. Application to sensitive areas of skin should be made with caution. In case of accidental contact, rinse well with water.
If excessive dryness or peeling occurs, frequency of application should be reduced or application temporarily interrupted.
Patients should be advised that excessive application will not improve efficacy, but may increase the risk of skin irritation.
During the first weeks of treatment, an increase in peeling and reddening may occur (see Section 4.8 Adverse Effects (Undesirable Effects)). Depending upon the severity of these side effects, patients can use a moisturiser, temporarily reduce the frequency of application of Duac Once Daily Gel or temporarily discontinue use; however, efficacy has not been established for less than once daily dosing frequencies.
Concomitant topical acne therapy should be used with caution because a possible cumulative irritancy may occur, which sometimes may be severe, especially with the use of peeling, desquamating, or abrasive agents.
If severe local irritancy (e.g. severe erythema, severe dryness and itching, severe stinging/burning) occurs, Duac Once Daily Gel should be discontinued.
The irritation potential of the agent may be increased if applied under occlusion.

Photosensitivity.

As benzoyl peroxide may cause increased sensitivity to sunlight, sunlamps should not be used and deliberate or prolonged exposure to sunlight should be avoided or minimised. When exposure to strong sunlight cannot be avoided, patients should be advised to use a sunscreen product and wear protective clothing.
If a patient has sunburn, this should be resolved before using Duac Once Daily Gel.
The product may bleach hair and coloured or dyed fabrics. Avoid contact with hair, fabrics, furniture or carpeting.
Patients should be advised that, in some cases, 4-6 weeks of treatment may be required before the full therapeutic effect is observed.

Pseudomembranous colitis.

Oral and parenteral clindamycin have been associated with severe diarrhoea and pseudomembranous colitis and may range in severity, with an onset of up to several weeks following cessation of therapy. Although this is unlikely to occur with topically applied clindamycin/ benzoyl peroxide, if prolonged or significant diarrhoea occurs or the patient experiences abdominal cramps, treatment should be discontinued immediately and the patient investigated further, as the symptoms may indicate antibiotic associated colitis. Suitable diagnostic methods, such as the determination of Clostridium difficile and toxin and, if necessary, colonoscopy should be employed and treatment options for colitis considered.

Resistance.

Prolonged use of clindamycin may lead to selection of resistant microorganisms and their overgrowth. Duac Once Daily Gel is recommended for a maximum duration of 11 weeks. There have been reports of Propionibacterium acnes resistance to clindamycin in the treatment of acne. If acne recurs, and a product containing a topical antibiotic or antiseptic is considered appropriate by their physician, the patient should be retreated with clindamycin 1%/ benzoyl peroxide 5% (Duac Once Daily Gel) to reduce the risk of development of cross resistance to other topical antibiotics.
Local recommendations about antibiotic use and prevalence of clindamycin resistance should be taken into consideration.
Benzoyl peroxide reduces the potential for emergence of organisms resistant to clindamycin (see Section 5.1 Pharmacodynamic Properties, Resistance development). Patients with a recent history of systemic or topical clindamycin or erythromycin use are more likely to have pre-existing antimicrobial resistant Propionibacterium acnes and commensal flora.
Cross resistance has been demonstrated between clindamycin and lincomycin. Resistance to clindamycin is often associated with inducible resistance to erythromycin (see Section 4.5 Interactions with Other Medicines and Other Forms of Interactions).
Clindamycin and erythromycin should not be used in combination.
Duac Once Daily Gel may not be adequate for severe nodulocystic acne.

Use in the elderly.

No data available.

Paediatric use.

No data available.

Effects on laboratory tests.

No data available.

4.5 Interactions with Other Medicines and Other Forms of Interactions

Concomitant topical antibiotics, medicated or abrasive soaps and cleansers, soaps and cosmetics that have a strong drying effect and products with high concentrations of alcohol and/or astringents should be used with caution as a cumulative irritant effect may occur.
No clinical studies have been conducted to assess interactions between Duac Once Daily Gel and other topical medications.
Duac Once Daily Gel should not be used in combination with erythromycin containing products. In vitro studies have shown antagonism between these two antimicrobials.
Oral clindamycin has been shown to have neuromuscular blocking properties that may enhance the action of other neuromuscular blocking agents. This effect is more common at higher doses of clindamycin. Therefore Duac Once Daily Gel should be used with caution in patients receiving such agents.
Concomitant application of Duac Once Daily Gel with tretinoin, isotretinoin and tazarotene may reduce their efficacy and increase irritation. If combination treatment is required, the products should be applied at different times of the day (e.g. one in the morning and the other in the evening).
Using topical benzoyl peroxide containing preparations at the same time as topical sulphonamide containing products may cause skin and facial hair to temporarily change colour (yellow/ orange).

4.6 Fertility, Pregnancy and Lactation

Effects on fertility.

There are no data on the effect of topical clindamycin or benzoyl peroxide on fertility in humans. Fertility was not impaired in male or female rats given benzoyl peroxide by oral gavage at doses up to 500 mg/kg/day, although male testes and epididymis weights were reduced at 1000 mg/kg/day, a dose which greatly exceeds that applied topically. Fertility was not impaired in rats given clindamycin phosphate 300 mg/kg/day in the diet.
There are no contraindications in women of childbearing potential who are practising adequate contraception. However, due to the lack of clinical studies in pregnant women, Duac Once Daily Gel should be used with caution when adequate contraception is not being practised.
(Category A)
Animal embryofoetal development studies have not been conducted with Duac Once Daily Gel. Administration of benzoyl peroxide by oral gavage to female rats throughout gestation and 3 days postpartum resulted in reduced pup bodyweights at 1000 mg/kg/day, but no pup gross external abnormalities. Reproductive studies have been performed in rats and mice using oral and parenteral doses of clindamycin phosphate up to 300 mg/kg/day and have revealed no evidence of harm to the foetus due to clindamycin. There are no well controlled studies in pregnant women treated with Duac Once Daily Gel.
There are limited data on the use of topical clindamycin or benzoyl peroxide alone in pregnant women. Animal studies do not indicate direct or indirect harmful effects with respect to reproductive toxicity. No effects during pregnancy are anticipated since systemic exposure to clindamycin and benzoyl peroxide is anticipated to be low.
It is not known whether Duac Once Daily Gel can cause foetal harm when administered to a pregnant woman or can affect reproductive capacity. Duac Once Daily Gel should be used during pregnancy only if the expected benefit justifies the potential risk to the foetus.
Duac Once Daily Gel has not been studied during breastfeeding.
Percutaneous absorption of clindamycin and benzoyl peroxide is low; however it is not known whether clindamycin or benzoyl peroxide is excreted in human milk after topical application. Oral and parenteral administration of clindamycin has been reported to result in the appearance of clindamycin in breast milk.
Duac Once Daily Gel should be used during lactation only if the expected benefit justifies the potential risk to the infant.
To avoid accidental ingestion by the infant if used during lactation, Duac Once Daily Gel should not be applied to the breast area.

4.7 Effects on Ability to Drive and Use Machines

There have been no studies to investigate the effect of clindamycin/ benzoyl peroxide on driving performance or the ability to operate machinery. A detrimental effect on such activities would not be anticipated from the adverse reaction profile of clindamycin/ benzoyl peroxide.

4.8 Adverse Effects (Undesirable Effects)

Adverse drug reactions (ADRs) are summarised below for topical clindamycin/ benzoyl peroxide as a combination including any additional ADRs that have been reported for the single topical active ingredients, benzoyl peroxide or clindamycin. Adverse drug reactions are listed by MedDRA system organ class and by frequency. Frequencies are defined as: very common (≥ 1/10), common (≥ 1/100 and < 1/10), uncommon (≥ 1/1,000 and < 1/100), rare (≥ 1/10,000 and < 1/1,000) very rare (< 1/10,000).

Clinical trials.

Very common (> 1/10).

Erythema, peeling, dryness.

Common (> 1/100, < 1/10).

Burning sensation, pruritus.

Uncommon (> 1/1000, < 1/100).

Dermatitis, paraesthesia, erythematous rash, worsening of acne.
In addition to the ADRs reported above for Duac Once Daily Gel, in a clinical trial conducted with a topical clindamycin and benzoyl peroxide (1%/3%) gel product, application site photosensitivity reaction was reported commonly.
In addition to the ADRs reported above for Duac Once Daily Gel, in a clinical trial conducted with a topical clindamycin product headache and application site pain were reported commonly.
Adverse events reported in five comparator clinical trials (studies 150, 151, 152, 156 and 158) by treatment arm are presented in Table 1.

Seven cases of diarrhoea were reported: Duac Once Daily Gel (n = 3), clindamycin gel (n = 1) and benzoyl peroxide gel (n = 3). Of the three cases in the Duac Once Daily Gel group, one case was attributed to E. coli food poisoning, which was successfully treated with antibiotics. The other two patients experienced short episodes of mild diarrhoea with no treatment or change in usage of study medication.
Contact sensitivity was reported in a patch test study (study 157) conducted on healthy volunteers. A total of 218 subjects were tested, of whom 18 (8.7%) developed allergic contact dermatitis after 3 weeks exposure to Duac Once Daily Gel. This incidence is similar to that observed historically (approximately 10%) at the investigative site for products containing benzoyl peroxide. It is anticipated that the incidence of sensitisation in clinical use will be much less than that reported in this study since semiocclusive patching exaggerates any intrinsic effect of topically applied substances to cause contact sensitisation.

Postmarketing data.

Immune system disorders.

Rare: allergic reactions including hypersensitivity and anaphylaxis.

Gastrointestinal disorders.

Rare: colitis (including pseudomembranous colitis), haemorrhagic diarrhoea, diarrhoea, abdominal pain.

Skin and subcutaneous tissue disorders (at site of application).

Rare: urticaria.

General disorders and administration site conditions.

Rare: application site reactions including discoloration.

Reporting suspected adverse effects.

Reporting suspected adverse reactions after registration of the medicinal product is important. It allows continued monitoring of the benefit-risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions at www.tga.gov.au/reporting-problems.

4.9 Overdose

No case of overdosage has been reported.
For information on the management of overdose, contact the Poisons Information Centre on 13 11 26 (Australia).

Symptoms and signs.

Excessive application of Duac Once Daily Gel may result in severe irritation (e.g. dermatitis, peeling and dryness). In this event, discontinue use and wait until the skin has recovered.
Topically applied benzoyl peroxide is not generally absorbed in sufficient amounts to produce systemic effects.
Excessive application of topically applied clindamycin may result in absorption of sufficient amounts to produce systemic effects (see Section 4.4 Special Warnings and Precautions for Use).
In the event of accidental ingestion of Duac Once Daily Gel, gastrointestinal adverse reactions similar to those seen with systemically administered clindamycin may be seen (e.g. nausea, vomiting and diarrhoea).

Treatment.

Appropriate symptomatic measures should be taken to provide relief from irritation due to excessive topical application.
Accidental ingestion or application should be managed clinically or as recommended by the Poisons Information Centre (13 11 26).

5 Pharmacological Properties

5.1 Pharmacodynamic Properties

Mechanism of action.

Clindamycin.

Clindamycin is a lincosamide antibiotic with bacteriostatic action against Gram positive aerobes and a wide range of anaerobic bacteria. Lincosamides such as clindamycin bind to the 23S subunit of the bacterial ribosome and inhibit the early stages of protein synthesis. The action of clindamycin is predominantly bacteriostatic, although high concentrations may be slowly bactericidal against sensitive strains.
Although clindamycin phosphate is inactive in vitro, rapid in vivo hydrolysis converts this compound to the antibacterial active clindamycin. Clindamycin activity has been demonstrated clinically in comedones from acne patients at sufficient levels to be active against most strains of Propionibacterium acnes. Clindamycin in vitro inhibits all Propionibacterium acnes cultures tested (MIC 0.4 microgram/mL). Free fatty acids on the skin have been decreased from approximately 14% to 2% following application of clindamycin.
Cross resistance may occur between clindamycin and other antibiotics such as lincomycin and erythromycin.
The prevalence of clindamycin resistance may vary geographically and with time for selected species. Local information of resistance is desirable, particularly when treating severe infections.

Resistance development.

Prolonged use of clindamycin may lead to selection of resistant microorganisms and their overgrowth. Duac Once Daily Gel was associated with reduced potential for emergence of resistance to clindamycin in Propionibacterium acnes compared to topical clindamycin alone in a clinical study of short duration.
Cross resistance may occur between clindamycin and other antibiotics such as lincomycin and erythromycin.
The prevalence of clindamycin resistance may vary geographically and with time for selected species. Local information of resistance is desirable, particularly when treating severe infections.
Antibiotic resistant propionibacteria may be transmissible between susceptible individuals. Physicians who routinely palpate patients' skin to assess acne severity should use cross infection control measures to avoid transferring resistant isolates between patients.

Benzoyl peroxide.

Benzoyl peroxide is keratolytic, acting against comedones at all stages of their development. It is an oxidising agent with bactericidal activity against Propionibacterium acnes, the organism implicated in acne vulgaris. Furthermore it is sebostatic, counteracting the excessive sebum production associated with acne.
Duac Once Daily Gel has a combination of keratolytic and antibacterial properties, providing activity against all the inflamed and noninflamed lesions of mild to moderate acne vulgaris.
Duac Once Daily Gel was associated with reduced potential for emergence of resistance to clindamycin in Propionibacterium acnes compared to topical clindamycin alone in a clinical study of short duration.
The presentation of both active ingredients in one product is more convenient and ensures patient compliance.

Clinical trials.

In five randomised double blind clinical studies of 1319 patients with facial acne vulgaris with both inflammatory and noninflammatory lesions, 397 used Duac Once Daily Gel, 396 used benzoyl peroxide, 349 used clindamycin and 177 used vehicle. Treatment was applied once daily for 11 weeks and patients were evaluated and lesions counted at 2, 5, 8 and 11 weeks.
Against inflammatory lesions, Duac Once Daily Gel was significantly more effective than clindamycin alone in four of five studies and to benzoyl peroxide alone in three of five studies. Against noninflammatory lesions, Duac Once Daily Gel was significantly better than clindamycin in four of five studies. Against noninflammatory lesions, Duac Once Daily Gel was significantly better than benzoyl peroxide in only one of five studies.
Overall improvement was assessed by the physician, and was significantly better with Duac Once Daily Gel than with either benzoyl peroxide or clindamycin alone in three of five studies. Table 2 reports results from the pivotal clinical study.

5.2 Pharmacokinetic Properties

Clindamycin.

In a maximised percutaneous absorption study, the mean plasma clindamycin levels during a four week dosing period for Duac Once Daily Gel were negligible (0.043% of applied dose).
The presence of benzoyl peroxide in the formulation did not have an effect on the percutaneous absorption of clindamycin.

Benzoyl peroxide.

Benzoyl peroxide is absorbed by the skin where it is metabolised to benzoic acid. Benzoic acid is mostly conjugated to form hippuric acid, which is excreted via the kidneys. Benzoic acid, too, has a wide margin of safety, and is an approved food additive.
In vivo data obtained with radiolabel procedures on urine specimens from rhesus monkeys indicated about 1.9% of the dose enters systemic circulation as benzoic acid.

5.3 Preclinical Safety Data

Genotoxicity.

Clindamycin phosphate was negative in assays evaluating the potential to cause gene mutations and chromosomal damage.

Carcinogenicity.

Benzoyl peroxide has been shown to be a tumour promoter and progression agent in a number of animal studies. Studies in mice have shown that benzoyl peroxide does not increase the growth of tumours initiated by UV light. Lifetime (104 week) carcinogencity studies with benzoyl peroxide dermally applied to mice (1%, 5%, 25/15% on approximately 6 cm²) and rats (1.6%, 5%, 15% on approximately 17.5 cm²) showed no evidence of carcinogenicity.
Long term studies in animals to evaluate the carcinogenic potential of Duac Once Daily Gel and clindamycin phosphate have not been performed.
A photocarcinogenicity study, in which hairless albino mice were exposed to a cumulative tumourigenic dose of simulated sunlight, showed that dermal application of Duac Once Daily Gel, for 5 days per week for 40 weeks, caused a statistically significant reduction in the median time to skin tumour onset. A slight reduction was also observed with the gel vehicle only. It is unclear whether these results have any clinical significance. Clinical use of Duac is likely to be much less extensive than that tested in mice.

6 Pharmaceutical Particulars

6.1 List of Excipients

Duac Once Daily Gel also contains carbomer 980, dimethicone 100, disodium lauryl sulfosuccinate, disodium edetate, glycerol, silicon dioxide, poloxamer, purified water and sodium hydroxide.

6.2 Incompatibilities

See Section 4.5 Interactions with Other Medicines and Other Forms of Interactions.

6.3 Shelf Life

In Australia, information on the shelf life can be found on the public summary of the Australian Register of Therapeutic Goods (ARTG). The expiry date can be found on the packaging.

6.4 Special Precautions for Storage

Instructions to the pharmacist.

Store at 2°C to 8°C for up to 2 years. (Refrigerate. Do not freeze).

Instructions to the patient.

Store at 2°C to 8°C for up to 2 months. (Refrigerate. Do not freeze).

6.5 Nature and Contents of Container

Duac Once Daily Gel is available in single 5, 6, 25, 30, 40, 45, 50, 55, 60 and 70 gram tubes. A physician's sample pack, a carton containing ten 6 gram tubes is also available.
Not all container sizes are available in Australia.

6.6 Special Precautions for Disposal

In Australia, any unused medicine or waste material should be disposed of by taking to your local pharmacy.

6.7 Physicochemical Properties

Clindamycin phosphate is a water soluble ester of the semisynthetic antibiotic produced by a 7(S)-chloro-substitution of the 7(R)-hydroxyl group of the parent antibiotic lincomycin. Synthesis also involves phosphorylation of the C(2)-OH group. It is a white to off white, odourless, hygroscopic, crystalline powder. It is soluble in water, slightly soluble in dehydrated alcohol, very slightly soluble in acetone and in alcohol and practically insoluble in chloroform, methylene chloride and ether.
Chemical name: methyl 7-chloro-6,7,8-trideoxy-6- (1-methyl-trans-4-propyl-L- 2-pyrrolidinecarboxamido)-1- thio-L-threo-α-D-galacto-octopyranoside 2-(dihydrogen phosphate).
Chemical formula: C₁₈H₃₄ClN₂O₈PS.
Molecular weight: 504.97.
Benzoyl peroxide is a white amorphous or granular powder with a characteristic odour which is practically insoluble to sparingly insoluble in water, slightly to sparingly soluble in alcohol, soluble in acetone, chloroform and ether and also soluble in methylene chloride with separation of water.
Chemical name: dibenzoyl peroxide. Molecular formula: C₁₄H₁₀O₄.
Molecular weight: 242.23.

Chemical structure.

Clindamycin phosphate.

Benzoyl peroxide.

CAS number.

CAS Number: 24729-96-2 - Clindamycin phosphate.
CAS Number: 94-36-0 - Benzoyl peroxide.

7 Medicine Schedule (Poisons Standard)

Schedule 4 - Prescription Only Medicine.

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Consumer medicine information

Duac Once Daily Gel

Clindamycin; Benzoyl peroxide

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