Repeat action tablets

Enteric coating is also used for repeat-action tablets, which contain an enteric-coated core tablet and a sugar or film-coated second dose, permitting the adininistration of two doses simultaneously. The core dose is released several hours after the initial, outer dose. 

Dissolution- and diffusion-based technologies can be utilized to obtain various novel profiles of drug release. For example, a repeat-action tablet can be created wherein the tablet provides two immediate release doses, with a time interval. This technology is used in Proventil Repetabs to provide two doses of albuterol (2 mg) separated by six hours. Acacia and carnauba wax are the polymers used in this specific case to provide two immediate release doses over a defined period. 

To provide a delayed release component for repeat-action tablets... 

Repeat action tablets Chlor-trimeton repetabs Pseudoephedrine, chlorpheniramine... 

A coating can be applied by compression using specially designed tablet presses. The same process can be used to produce layered tablets which can comprise two or even three layers if complete separation of the ingredients is required. This process is used when physical separation of ingredients is desired due to incompatibility or to produce a repeat-action product. The formulation can also be designed to provide an immediate and a slow-release component. Release rates can be controlled by modification of the geometry, the composition of the core, and the inclusion of a membrane layer. 

Compressed Tablets. This popular type of dosage form offers convenience, stabiUty, accuracy and precision, and good bioavadabihty of active ingredients. After the best formulation has been estabflshed, compressed tablets can be manufactured at high rates of speed on advanced equipment. Tablets can be made to achieve rapid dmg release or to produce delayed, repeat, or prolonged therapeutic action (Controlled release technology, pharmaceutical). ... 

Naratriptan 1-2.5 mg tablets and repeat after 4 hours onset of action is slower but has the second longest half-life has less side effects... 

F. Repeat-dose activated charcoal. Repeated doses of activated charcoal (20-30 g or 0.5-1 g/kg every 2-3 hours) are given orally or via gastric tube. The presence of a slurry of activated charcoal throughout several meters of the intestinal lumen reduces blood concentrations by intermpting enterohep-atic or enteroenteric recirculation of the dmg or toxin, a mode of action quite distinct from simple adsorption of ingested but unabsorbed tablets. This technique is easy and noninvasive and has been shown to shorten the half-life of phenobarbital, theophylline, and several other dmgs (Table 1-41). However, it has not been shown in clinical trials to alter patient outcome. Caution Re-peat-dose charcoal may cause serious fluid and electrolyte disturbance secondary to large-volume diarrhea, especially if premixed charcoal-sorbitol suspensions are used. Also, It should not be used in patients with ileus or obstmction. 

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