Topically Applied Dosage Forms

Full update July 2022

Pharmacy technicians dispense a variety of dosage forms that are for topical application, such as creams, foams, gels, lotions, ointments, sprays, patches, or suppositories.

Topically applied medications are usually intended to deliver medication to a particular place on or in the body, such as the skin or mucous membranes (i.e., membranes that line and protect some parts of the body, such as the mouth, nose, eye, vagina, or rectum). For instance, they may be used to treat chronic skin conditions, such as acne, eczema, or psoriasis, or acute skin conditions, such as burns, infections, or bites or stings. However, some topically applied medications, such as transdermal patches, may be placed on the skin, but are absorbed into the bloodstream for systemic (whole body) effects. For example, patch dosage forms are available for smoking cessation or to treat high blood pressure.

Many eye drops, ear drops, and nasal sprays are considered topical dosage forms. This is because they usually act locally where they’re applied. You can find more details about these topical meds in the tutorial, The Ins and Outs of Eye and Ear Meds.

Sometimes topical dosage forms must be specially compounded in the pharmacy, such as diaper rash treatments or “magic mouthwash” that is used for mouth sores. For more information about compounding topical products, see our tutorial, Non-Sterile Compounding Basics.

 

Mary, a 32-year-old female, is in the pharmacy today to pick up the above electronic prescription (e-Rx) for betamethasone 0.05%, apply to palms of both hands twice daily for 10 days, quantity of 1. Mary is a massage therapist. She tells you that she has been having a bad skin reaction to a new product she tried at work. She holds her hands out, and indeed the palms look red and irritated.

You haven’t had a chance to fill the prescription yet, but Mary tells you she doesn’t mind waiting while you get it ready. You review her medication list and see that the only other prescriptions she has filled at your pharmacy are her birth control pills and a one-time Rx for ciprofloxacin. You ask if she has any new allergies or if she takes any other medications, such as OTCs or supplements. She confirms that she does not. As you start to enter her prescription into the computer, you notice that there are a variety of different dosage forms of betamethasone. There are two different salts: betamethasone dipropionate and betamethasone valerate. And there are a variety of formulations: creams, ointments, lotions, gels, and sprays; some of which are labeled as “augmented.” You notice in the e-Rx notes that the prescriber has indicated either the ointment or augmented cream may be dispensed. However, you still aren’t 100% sure which product you should select, so you check with the pharmacist.

What are the main types of topically applied dosage forms?

There are distinct differences between different topically applied dosage forms.

• Creams are opaque and nongreasy to moderately greasy. When rubbed into the skin, creams are mostly absorbed and spread easily. Creams work well for most areas, including areas that are weeping or oozing and mucous membranes, such as those of the rectum and vagina.
• Gels are translucent and nongreasy. Gels provide a cooling sensation when applied to the skin and can dry quickly. Gels are good for hairy areas and skinfolds. They may also be used on the mucous membranes of the rectum and vagina.
• Lotions are opaque, thinner than creams, and nongreasy. Lotions evaporate rapidly when rubbed onto the skin and may also provide a cooling sensation. Lotions are good for hairy areas or parts of the body where there might be friction, like the armpits.
• Ointments are opaque or translucent, thick, and often greasy. They have an “emollient” effect that helps rehydrate skin. Ointments can leave an oily coating when rubbed onto the skin, are sticky, and may leave grease stains on clothing. Ointments are good on skin that needs protection, or on dry, scaly areas. They may also be used on mucous membranes of the rectum and vagina.
• Pastes are opaque; thicker than creams, gels, and lotions; and are greasy. Pastes aren’t well absorbed into the skin, so they are often used to provide a protective layer.
• Patches are adhesive pads that contain medication. They are usually one piece, but may be two pieces, with a medicated portion and a cover. Patches are designed to stick to the skin and typically deliver time-released doses of medication. While many patches are intended to provide systemic effects, some patches, such as the pain reliever lidocaine, are used for their local effects, similar to other traditional topical medications like creams or ointments.
• Suppositories are a conical or cylindrical-shaped semi-solid dosage form that is typically inserted into the rectum or vagina. Suppositories are designed to melt at body temperature but are hard enough to handle for administration.

Additionally, certain solutions and suspensions, such as those for acne, like clindamycin (Clindacin-P [US], etc) and erythromycin, are applied topically. You may also dispense other less commonly used topical dosage forms not mentioned above, such as foams (a pressurized dosage form which upon actuation delivers a liquid or semi-solid product that is expanded with air), sprays (a pressurized dosage form which upon actuation delivers a fine mist), or powders (a solid dosage form that is a dry mixture of finely divided active and inactive ingredients).

Can one topical dosage form be substituted for another if the active ingredient is the same?

If a prescriber writes for a specific formulation of a product that comes in more than one dosage form (i.e., the Rx says “ointment,” but the product is also available as a cream), the prescribed formulation should be dispensed. If the prescriber doesn’t specify, let the pharmacist know. Despite their similarities, topical products with similar sounding names or different salt forms, such as hydrocortisone acetate, hydrocortisone butyrate (US), and hydrocortisone valerate, can’t always be automatically substituted for each other. If needed, check with the pharmacist first to identify if there is a substitutable product and follow your state laws or provincial regulations and pharmacy policies for substitution.

The pharmacist tells you that since betamethasone valerate doesn’t come in an augmented version and is available in a cream and ointment strength of 0.1% (not 0.05% as indicated on the e-Rx), it’s most likely that the prescriber meant to order betamethasone dipropionate, either the ointment or augmented cream, as indicated in the e-Rx notes. The pharmacist says that he will still call the prescriber to confirm and to also check on a more specific quantity to dispense since the e-Rx just said a quantity of “1.”

The prescriber says she would like the betamethasone dipropionate 0.05% ointment to be dispensed, but if that is unavailable or too expensive for the patient, the augmented cream can be dispensed instead. Since it’s a little thicker and greasier, the ointment should have more staying power. The prescriber also says to just dispense whichever size tube will provide enough medication for a full 10 days of therapy.

How should I determine how much of a topically applied med to dispense and the days’ supply?

Pay attention when calculating quantities and days’ supply of topically applied meds, since this can be trickier compared to oral med prescriptions.

The prescriber will usually write how much of a topical med to dispense. However, if that information is not included on the prescription, or if instructions are vague, such as “use as directed” or “apply to affected area,” you might need to ask the patient for more details. You’ll want to dispense enough medication to last for the patient’s full course of therapy. Otherwise, the patient may have to come in for frequent refills. You also don’t want to dispense too much medication, which could be an audit flag to insurance companies. We have more on this in our tutorials, Billing Rx Drugs and Calculating Days’ Supply.

Make sure you understand the units for quantity in your computer system. For example, entering “1” for one box of patches could be confused to mean one patch, and vice versa. If you are unsure of which quantity to enter, check with your pharmacist.

For topical creams or ointments, you may need to find out the general size of the area being treated to determine how large of a package size to dispense (if the prescriber doesn’t specify). Then you can use the “Rule of Hand” to calculate days’ supply. One gram of the topical med will cover the area of about four flat hands, wrist to fingertips with fingers together (i.e., four handprints).

Another method you can use is called the “fingertip unit.” The fingertip unit is the amount of a topical preparation that can be squeezed out of a standard tube along an adult fingertip (from the tip of the finger to the crease of the first joint). One fingertip unit is about 0.5 g, or 500 mg, of the topical cream or ointment.

You can use the following for estimating the quantity needed with fingertip units (assume an average-size adult):

• 1 fingertip unit (0.5 g) covers both sides of an adult hand with fingers together
• 5 fingertip units (0.75 g) cover one adult foot
• 5 fingertip units (1.25 g) cover an adult face and neck
• 4 fingertip units (2 g) cover one entire adult arm and hand
• 8 fingertip units (4 g) cover one entire adult leg and foot
• 8 fingertip units (4 g) cover the adult trunk, either front or back

Mary will be applying betamethasone dipropionate ointment to the palms of both hands twice a day for 10 days. To cover one side of the hand she will use about one-half of a fingertip unit for each application. Since she will be doing this twice a day to both hands, she’ll need about two fingertip units each day. This is about 1 g of ointment per day. So, 1 g per day for 10 days is 10 g (1 g x 10 days = 10 g). You select the smallest size tube available that is closest to that amount which is 15 g. You double-check your estimation with the pharmacist, and he agrees.

Keep in mind, drug patches are generally packaged in a box with a set number of patches. You will need to determine how many boxes are needed to fill the prescription based on the number of patches in each box and how the patient will be using the patch. For example, fentanyl boxes usually contain five patches. The normal dose is one patch every three days, which would equal two boxes of fentanyl patches for a 30-day supply (1 patch/3 days x 30 days = 10 patches; 1 box/5 patches x 10 patches = 2 boxes). For clonidine patches (US), that are changed weekly, there are four patches per box, so just one box is needed for a 28-day supply.

Be aware of unique situations, such as with some vaginal meds that have out-of-the ordinary sigs. For example, Annovera (US) vaginal contraceptive ring is a 364 days’ supply since one ring is reused for 13 menstrual cycles and each cycle is 28 days (28 days/cycle x 13 cycles = 364 days). And if a patient is inserting one vaginal estradiol insert, such as Yuvafem (US), into the vagina twice weekly, dispensing a carton of 8 inserts will last 28 days (1 week/2 inserts x 8 inserts x 7 days/1 week = 28 days).

In the hospital, it’s also important to dispense an appropriate amount of a topically applied product. As in the outpatient setting, the amount to dispense will usually be specified in the order. If it’s not, ask the pharmacist. The patient might require just a small amount of medication for some conditions (a small sore, athlete’s foot, ringworm, etc), but you might also encounter situations where a patient is using a very large amount of medication for extensive application (e.g., burns, Stevens-Johnson syndrome). You might notice this after the fact if the drug is being reordered very frequently. If that’s the case, take the time to investigate the situation and let the pharmacist know. In both the inpatient and outpatient settings, adjusting the amount of drug to the most appropriate package size will save everyone time in the long run.

What should I watch for when dispensing topically applied dosage forms?

There are lots of different things that can lead to mix-ups or confusion with topically applied dosage forms. We already covered the differences between dosage forms (creams, ointments, etc). In addition to this, some topicals also come in several different strengths. Topical steroids in general are great for illustrating this, and a specific example is hydrocortisone cream. It comes in at least three different strengths (e.g., 0.5%, 1%, 2.5%, etc). Just as topicals that come as both creams and ointments may have similar packaging, these different strengths may also be packaged very similarly. Drug patches can also come in several different strengths. For example, estradiol patches come in twice-a-week and weekly formulations in strengths of 0.025 mg (25 mcg), 0.0375 mg (37.5 mcg), 0.05 mg (50 mcg), 0.075 mg (75 mcg), or 0.1 mg (100 mcg). Fentanyl patches also come in several different strengths, such as 12, 25, 50, 75, and 100 mcg/hour. Be extra cautious that you are picking the correct strength.

Different salt forms can cause confusion, too. As we see in the patient case, betamethasone is a good example. It comes as betamethasone dipropionate and betamethasone valerate.

Plus, betamethasone comes in an augmented form too, which means that it’s in a vehicle (propylene glycol) which helps increase absorption of the drug, making it more potent. Increased potency can mean that the drug is more effective, but it can also mean there’s a higher risk for side effects. These products shouldn’t be interchanged, and one reason for this is the difference in potency. For instance, augmented betamethasone dipropionate ointment is considered a very high-potency steroid while betamethasone dipropionate cream is a medium-potency steroid. High- or very high-potency steroids should generally not be used on areas of the body with thinner or more sensitive skin, such as the face, skinfolds, armpits, or groin area. Using high- or very high-potency steroids on these areas can cause irritation and increase the chance for systemic absorption and side effects. Be careful that you choose the right steroid when entering the prescription in the computer and when pulling the product from the shelf during dispensing. If you feel like you need more information to choose the right product, let the pharmacist know. For a list of the different topical steroids, including dosage forms, package sizes, cost, and relative potencies, check out our chart, Comparison of Topical Corticosteroids for US and Canada.

Be on the lookout for look-alike/sound-alike topical drugs. For instance, mix-ups can easily happen between fluocinolone and fluocinonide; desonide (US) and desoximetasone; trifarotene (Aklief) and tazarotene (Tazorac, etc);or tacrolimus (Protopic) and pimecrolimus (Elidel). And Cortifoam can be confused with Cortisone; Estring with EluRyng (US); clotrimazole with miconazole; Diastat with Diabeta; and MetroGel with MetroGel Vaginal.

If the duration of therapy is indicated on the Rx sig, be sure to include that in the Rx directions for the patient. This is especially important for topical steroids that should usually only be used for a limited time period to decrease the risk of side effects, such as thinning of the skin, skin irritation, changes in skin color, or acne. This is also important for vaginal antibiotic (e.g., clindamycin 2% vaginal cream [Cleocin (US), Dalacin (Canada), etc]) or vaginal antifungal (e.g., miconazole [Monistat, etc]) creams that need to be used for a certain number of days in order to the clear the vaginal infection.

Watch for patients’ allergies, too. A fairly common one is a sulfa allergy. Patients who are severely allergic to sulfa drugs shouldn’t get silver sulfadiazine cream (Silvadene [US], Flamazine [Canada], etc).

You should also note if a patient is currently pregnant or breastfeeding. Many topical meds are okay for these patients to use. But there are some, such as adapalene (Differin) and tretinoin (Retin-A, etc), which may need to be avoided.

You enter the prescription into the computer system including directions that say, “Apply to the palms of both hands twice a day.” You re-read the e-Rx and notice that you forgot to add “for 10 days” to the end of the prescription instructions. You remember that this information needs to be included on the Rx, so you go back and add it before submitting the claim. Using a topical steroid ointment such as betamethasone dipropionate for longer than necessary could lead to undesirable side effects. Plus, since the duration was included in the e-Rx sig, it must be included in the directions that are provided to the patient. Otherwise, this would be considered a dispensing error.

Is there any special labeling required for topically applied dosage forms?

Topically applied medications should usually have an auxiliary label that says, “For external use only.” It’s a good idea to specify where the product should be used, if you can (e.g., “For rectal use only” or “For vaginal use only”). It may seem obvious that topical dosage forms aren’t to be swallowed. But there have been situations where a patient misunderstood how to use the topical product and swallowed it instead. For example, there have been reports of patients swallowing OTC topical diphenhydramine (Benadryl) gel, where hospitalization or emergency treatment was required for these individuals. Clear labeling is important to help prevent these types of problems and ensure proper use of topical products.

Of course, any topically applied dosage form that requires refrigeration (e.g., promethazine rectal suppositories [US]) should get a “Refrigerate” label. Keep in mind that some meds you keep refrigerated in the pharmacy can be stored at room temperature after being dispensed to the patient (e.g., benzoyl peroxide/clindamycin gel [Neuac (US), Clindoxyl (Canada), etc], clascoterone cream [Winlevi (US)], estrogen/norethindrone acetate patch (CombiPatch [US] and Estalis [Canada]). While these meds don’t need a “Refrigerate” auxiliary label, they often need a “Use by” or “Discard after” label, since they are usually only good for a limited time at room temp. For instance, benzoyl peroxide/clindamycin gel is only good for 60 days after it’s dispensed.

Rectal or vaginal creams and suppositories might be more convenient and less messy for patients when they are used at bedtime, so consider adding a “Bedtime” label to these.

Be aware that many topically applied dosage forms often come in packages that are not child resistant (patches, creams, ointments, etc). It is important that the patient realizes this and stores the medication in a safe place that is out of reach of children and pets. To alert patients about this, always apply an auxiliary label that says, “Package not child resistant” and/or “Keep out of reach of children.”

Some products, such as topical foams or suspensions, may require a “Shake well” label. For instance, minocycline topical foam (Amzeeq [US]) must be shaken before use to properly foam. And, calcipotriene/betamethasone dipropionate topical suspension (Taclonex [US]) must be shaken before use to ensure the medication is evenly dispersed.

Many topically applied dosage forms come with the manufacturer’s patient labeling (“Patient Package Inserts” and “Instructions for Use” in the US or “Patient Medication Information” in Canada). These documents include important details on how to use and dispose of the medication that the patient can refer back to after they’ve received pharmacist counseling. Pay attention to products that come with patient labeling, such as by being attached to or included within the product packaging and include this for the patient when dispensing the product whenever possible.

Be aware that the US Food and Drug Administration (FDA) requires that a MedGuide be dispensed with some drug patches (fentanyl, Emsam, Daytrana, etc). When MedGuides are required, they must be dispensed with every new Rx and refill in the outpatient setting. MedGuides are usually included with the product insert inside of the package. But if you aren’t sure if the package contains a MedGuide, or if you are dispensing loose patches, make sure to dispense the MedGuide with it. MedGuides are important because they focus on providing patients with information that can help prevent serious adverse events. This may include disposal instructions, such as with fentanyl patches. There have been cases of toxicity and death from children applying or ingesting discarded fentanyl patches, so it’s recommended to dispose of these by folding the patch so that it sticks to itself and then immediately flushing the patch down the toilet if a drug take-back option isn’t readily available. (Note that flushing of meds is not recommended by Health Canada.)

As you label Mary’s betamethasone dipropionate ointment, you make sure to apply an auxiliary label indicating that it is for external use. You let the pharmacist know the Rx is ready to check.

Cite this document as follows: Technician Tutorial, Topically Applied Dosage Forms. Pharmacist’s Letter/Pharmacy Technician’s Letter. July 2022. [380780]

 

“Cheat Sheet” for Topically Applied Dosage Forms

What are some examples of topically applied dosage forms?

Topically applied dosage forms usually act locally where they’re applied but may also be used to deliver drugs systemically (whole body). They are used to treat a wide range of conditions, such as acne, eczema, psoriasis, burns, infections, or bites or stings. Some common examples include:

• creams (opaque and nongreasy to moderately greasy). When rubbed into the skin, creams are mostly absorbed and spread easily. Creams work well for most areas, including areas that are weeping or oozing and mucous membranes, such as those of the rectum and vagina.
• gels (translucent and nongreasy). Gels provide a cooling sensation when applied to the skin and can dry quickly. Gels are good for hairy areas and skinfolds. They may also be used on the mucous membranes of the rectum and vagina.
• lotions (opaque, thinner than creams, and nongreasy). Lotions evaporate rapidly when rubbed onto the skin and may also provide a cooling sensation. Lotions are good for hairy areas or parts of the body where there might be friction, like the armpits.
• ointments (opaque or translucent, thick, and often greasy). They have an “emollient” effect that helps rehydrate skin. Ointments can leave an oily coating when rubbed onto the skin, are sticky, and may leave grease stains on clothing. Ointments are good on skin that needs protection, or on dry, scaly areas. They may also be used on mucous membranes of the rectum and vagina.
• pastes (opaque; thicker than creams, gels, and lotions; and greasy). Pastes aren’t well absorbed into the skin, so they are often used to provide a protective layer.
• patches (adhesive pads that contain medication). They are designed to stick to the skin and typically deliver time-released doses of medication. While many patches are intended to provide systemic effects, some patches, such as the pain reliever lidocaine, are used for their local effects, similar to other traditional topical medications like creams or ointments.
• suppositories (conical or cylindrical-shaped semi-solid dosage). Suppositories are typically inserted into the rectum or vagina. Suppositories are designed to melt at body temperature but are hard enough to handle for administration.

What should I be sure to do when dispensing prescriptions for topically applied medications?

• Watch for topicals that come in several different strengths or dosage forms (ointments, creams, lotions, etc) and drugs that come in different salts (e.g., hydrocortisone acetate and hydrocortisone valerate) to ensure you’re picking the correct product.
• Be alert for look-alike/sound-alike drugs, such as fluocinolone and fluocinonide.
• Check with the pharmacist if you are unsure about substituting a product that isn’t in stock.
• Include all info from the Rx sig when typing directions, such as duration of therapy or indications.
• Read the entire e-Rx, paying attention to information in the “notes” section for additional sig details, information on duration of therapy, indications, substitution instructions, etc.
• Calculate the correct quantity and days’ supply. For creams, ointments, gels, etc, determine the general size of the area being treated and use a guide such as the “Rule of Hand” or “fingertip unit” to estimate the amount of drug in grams that will be used with each application.
• Select the package size that is closest to the quantity of medication that will last the patient for the duration of therapy (if the specific package size isn’t indicated by the prescriber).
• Apply “For external use only” auxiliary labels and when able, specify where the product should be used (e.g., “For vaginal use only”). Apply auxiliary labels to products that require refrigerator storage, must be shaken before use, should be applied at bedtime, or have a beyond-use date.
• Refer patients to the pharmacist for counseling on how the topical should be administered/used.

[July 2022; 380780]