mediamedika.net

Secara fisiologis, proses penuaan sangat merubah proses farmakokinetik dan farmakodina,nik obat. Kapasitas fu dan organ-organ penting ,nenurun sirkulasi darah metabolisme di hepar, ekskresi lewat ginjal berpengaruh hesar terhadap perubahan kadar obat dalam darah; penurunan kadar albumin serum akan nienaikkan kadarfraksi obat bebas dengan demikian efekfarma kologisnya juga meningkat . Perubahan-perubahan tersebut akan men urunkan keperluan dosis lazim dan pemberian dosis lantak bisa sampai separuhnya, misal digoxin. Dalam banyak hal perlu dilakukan pemeriksaan kadar obat di dalam darah. Metabolisme hepar dan ekskresi ginjal menurun sehingga waktu paro obat menjadi lebih panjang. Mekanisme kontrol homeostatik menumpul
yang juga mempengaruhi intensitas respon penderita. Pasien usia lanjut pemberian dosis obat harus diturunkan banyak dan dosis lazim (75 tahun ke atas) baru kemudian dinaikkan secara gradual sampai dosis yang dibutuhkan. Terapi polifarmasi harus betul betul diperhitungkan untung ruginya.

Physiologically, aging process followed by changing of pharmakokinetic and pharmacodynamic process. Functional capacity of major organ system is declining of blood circulation, hepatic metabolism and renal excretion influence on plasma drug concen tration. Decreasing of in albumin serum will increase the free drug concentration (fraction), which also influence their pharma cological effect. Those changes may alter the appropriate usual dose and !oading dose and loading dose of a drug become lower than usual, for example dixogin: its loading and maintenance dose should be reduced propotionarely. In some situation the drug plasma concentration needs to be monitored. Drug are metabolized and excreted more slowly so the half-l of a drug become longer. Homeostatic controls mechanism is decreasing that may change the intensity of drug response. In elderly patient the dose of a drug to be administrated must be reduced to such extent and titrate gradually until appropriate dose. Therapy polypharmacy must be carefully just i the benefit should be considerated over the risk of adverse drug reaction.