Transdermal drug delivery thickness

In 1992 the 3 M disclosed blends that comprised 100 parts VLDPE [Flexomer or Attane 80-95 mol% ethylene and 5 mol% C4 g comonomer(s)] and 15-600 parts m-LLDPE [DOWLEX ethylene copolymer with 2-8 mol% Cg]. The blends showed excellent processability. Formed into 10-300 pm thick films, they were used for transdermal drug delivery devices as single-layer backings. The films were clear, colorless, transparent to visible light, and sealable at relatively low temperature. They were permeable to O2, stable to various common components of transdermal delivery devices, strong, and comfortable and did not absorb significant amounts of common elements of transdermal carriers (Godbey and Martin 1993, 1994). 

A Si microneedle has been fabricated, though the application was not in making the ESI tip, but in transdermal drug or vaccine delivery. Figure 7.40 shows how the microneedle penetrates a 10-pm-thick A1 foil. This needle has the openings in the shaft, rather than in an orifice at the tip [791]. 

Although differences in surface characteristics, such as smoothness and the presence of hair, might be expected to influence TDB from transdermal dose forms, there are limited supportive data. Evidence suggests that differences in sebum sheet thickness between different sites may contribute to differences in the delivery of drugs to the It is also reasonable... 

HA has been used as a hydrophihc carrier to deliver diclofenac topically for the treatment of premalignant skin lesions such as actinic keratoses (AK) (106-112) and for colon-26 adenocarcinoma (113-115). HA is the preferred carrier for transdermal delivery of diclofenac, as it has been shown to enhance the partitioning of the drug into the skin compared to other vehicles (116). Furthermore, in a clinical trial, the safety and efficacy of 3% diclofenac in 2.5% HA gel have been evaluated as a topical treatment for actinic keratosis (108). Patients treated with HA-diclofenac showed significantly lower target and cumulative lesion number scores and lesion total thickness scores compared to the placebo group. The treatment with 3.0% diclofenac in 2.5% HA gel was effective when used for 60 days and was well tolerated in patients with AK. 

Transdermal scopolamine is a muscarinic receptor antagonist used for the prevention of post-operative nausea and vomiting. It is supplied as a circular adhesive patch (0.2 mm thick and 2.5 cm ) applied to the post-auricular skin. Each patch contains 1.5 mg of the belladonna alkaloid programmed to continuously release in vivo approximately 1.0 mg over 72 hours. The patch consists of four distinctive layers. Going from visible surface to the surface adherent to the skin, these layers are (1) backing layer (2) drug reservoir of scopolamine (3) microporous polypropylene membrane that controls the rate of scopolamine delivery (4) adhesive contact surface with the skin. 

---